Earticle

북한의 일당체제는 노동당의 역할과 위상을 강화시켜 모든 기관과 단체, 주민을 당 조직 에 소속시켜서 정치적 조직생활에 참여하도록 하고 있다. 또한, 2016년 5월 6일 제7차 당 대회에서는 김정은을 노동당위원장으로 추대하였고, 6월 29일 최고인민회의에서 국무위원 회를 신설하여 김정은을 국무위원장으로 추대하여 당과 국가기구를 아우르는 1인 체제를 구 축하였다. 북한은 국가사회통제기관과 사회/근로단체를 통해 당과 수령주의에 인민대중을 결집시키 고 있으며, 수령의 정치적 권위를 정통화하고 수령과 당의 정책노선 실현을 위해 인민대중 을 조직·동원하는 역할과 사상교육으로 인민대중을 혁명화 시키기 위해 사회통제기제와 조 직생활을 통하여 주민들을 통제하고 있다. 1990년대 중반 이후 배급제가 무너지면서 식량난이 가중(加重)되면서 사회통제 소홀로 주민들에 대한 거주이전과 이동통제가 이완되고 있으며, 븍한이탈주민들이 지속적으로 증가 하여 2018년 현재 32,000여 명이 발생되었고, 2003년 종합시장제 이후로 부(富)가 축적 됨에 따라 주민들의 생활수준과 소득에 따른 계층화가 상·중·하층 3부류로 범주화되고 있다. 이와 같이 북한은 주민통제와 조직생활에도 불구하고 사회통제의 이완과 북한이탈주민 증가, 그리고 사회계층 구조가 변동되는 등 변화가 일어나고 있다. 하지만, 주민통제와 조직생활을 통하여 사회통제기구를 강화하더라도 북한체제의 안정을 단기적으로는 유지할 수가 있으나, 중·장기적으로는 계속하여 체제의 불안정을 증가시키는 요인으로 경제문제가 지속적으로 대두가 될 것이다. 북한의 경제체제는 구조적으로 경제운영 노선을 인민경제·수령경제·군수경제·시장경제의 네 가지 경제의 영역과 기능을 상호관계 속에서 서로 영향을 미치고 있으면서 체제의 안정 성과 불안정성을 표출하는 역할로 상존하고 있다. 특히, 시장경제의 활성화로 권력기관과 국가재정이 시장에 기생하고 있고, 정경유착으로 부익부 빈익빈현상이 심화되고 있으며, 시장을 통해 외부정보 유입으로 사상적 이완과 물질 주의가 팽배하고 있다. 향후 남·북/미·북 관계 개선으로 북한은 중국식 개혁개방, 즉 정치체제는 일당독재체제를 유지하면서 점차적으로 경제체제를 자본주의 시장경제로 전환될 것으로 전망하기에 북한체 제의 안정성 진단은 의미가 있다고 본다.

North Korea 's one - party system strengthens the role and position of the Labor Party, so that all organizations, groups and residents belong to the party organization and participate in political organization. On May 6, 2016, the 7th Party Congress held Kim Jeong Eun as the Chairman of the Labor Party. On June 29, the Supreme People's Assembly established the State Council and appointed Kim Jeong Eun as the chairman of the National Assembly. They have established one-person system that governs the party and the nation. North Korea has mobilized the masses of the people in the party and Chief caution through the state social control agencies and social / labor groups, and has the role of organizing and mobilizing the public in order to receive and receive the political authority of guvnor, In order to revolutionize the public through ideological education, people are controlled through social control mechanisms and organizational life. Since the mid-1990s, the distribution system has been overloaded and the food shortage has been weighted. As a result, the residence and North Korean defectors has been loosened due to the lack of social control and the number of defectors has steadily increased to 32,000 as of 2018, In 2003, as a result of additional accumulation since the market system, stratification according to the living standard and income of the residents has been categorized into three categories: upper, middle, and lower. Thus, in spite of the resident control and organization life, North Korea is experiencing changes such as relaxation of social control, increase of defectors, and social hierarchy. However, it is possible to maintain the stability of the North Korean regime in the short term, even if it strengthens the municipal control system through the inhabitants' control and organizational life. However, economic problems will continue to increase instability in the medium to long term. North Korea's economic system is structurally related to the economic operation, the People’s economy, the guvnor economy, the military economy, and the market economy. Especially, due to the activation of the market economy, the power institutions and the national finance are parasitized to the market, and the phenomenon of rich and poor people is deepening due to canonical cohesion, and the inflow of external information through the market is leading to an ideological relaxation and materialism. In the future, the improvement of South Korean and North Korean / US and North Korean relations will lead to the Chinese reform and openness, It is expected that the political system will be maintained and the economic system will be gradually shifted to the capitalist market economy. The diagnosis of the stability of the North Korean system is meaningful.

PURPOSE: The purpose of this study is to conduct inter-rater and intra-rater reliability tests in patients with low back pain (LBP) using the prone instability test (PIT) and side-lying instability test (SIT). We have analyzed the Korean version Oswestry disability index (K-ODI) correlations and radiograph finding (RF) for validity. METHODS: Individuals (n = 51) (mean age of 40.27 ± 13.28) with LBP for at least over a week were recruited, together with two participating physical therapist examiners. The measurement consisted of PIT, PST, K-ODI, and RF. Sensitivity (Sn), specificity (Sp), positive predictive value, negative predictive value, prevalence index, agreement %, Cohen's kappa, and prevalence-adjusted bias-adjusted kappa (PABAK) were calculated. The PIT and SIT were compared with RF for validity analysis, while PIT, SIT, K-ODI, and RF were calculated for the correlation analysis. RESULTS: The intra-rater reliability test measured for the PIT (kappa = .79, PABAK = .88) and SIT (kappa = .73, PABAK = .84), and inter-rater reliability test measured for the SIT (kappa = .80, PABAK = .88) showed good agreements. The PIT (Sn = .65, Sp = .63) and SIT validities (Sn = .68, Sp = .70) were compared with RF, showing a significant correlation in PIT and RF (r = .69), SIT and RF (r = .73), and PIT and K-ODI (r = .53). CONCLUSION: The SIT is a more comfortable position test than the PIT in patients. Both PIT and SIT have acceptable reliability and validity.

Purpose: Chronic ankle instability (CAI) is prevalent among Taekwondo athletes because of the repetitive jumping, landing, and rotational movements. While ankle-centered strengthening is commonly used, proximal hip muscles also contribute to lower-limb alignment and dynamic stability. This study examined the effects of hip extensor and abductor strengthening on the ankle instability and balance in Taekwondo athletes with CAI. Methods: Twelve male collegiate Taekwondo athletes with CAI (CAIT ≤24) were assigned randomly to an experimental group (n=6) or a control group (n=6). All participants completed a 15-minute ankle strengthening program. The experimental group also completed 15 minutes of hip strengthening, whereas the control group performed ankle stretching. Training was conducted five times per week for three weeks. Functional ankle instability (CAIT), static balance (average velocity, path length, area 95% COP), and dynamic balance (Y-balance test and functional reach test) were measured before and after intervention. A two-way repeated-measures ANOVA was used for analysis (p<0.05). Results: Both groups showed significant improvements in ankle instability and balance (p<0.05). No significant interaction effect was found for ankle instability (p>0.05). Nevertheless, significant time×group interactions were observed for static and dynamic balance (p<0.05), with greater improvements in the experimental group. Conclusion: Hip and ankle strengthening effectively enhanced balance in Taekwondo athletes with CAI, providing superior benefits over ankle-focused training alone. These findings support the inclusion of proximal hip strengthening in rehabilitation programs to improve balance control and contribute to ankle stability in athletes with CAI.

Estimating workability is very important to complete the hot or cold working process successfully without making any crack. Instability map was developed by utilizing conventional plastic work criterion in the current study. Hot compression tests were conducted using Gleeble 3800 simulator to obtain flow stress curves as a function of temperature and strain rate. Based on the compression results, new instability map based on the specific plastic work was developed for estimating the instability during the hot deformation process. The critical specific plastic work value was determined by investigating the surface irregularity and shear band formation in the compressed specimens. Then, the instability map determined was applied for predicting surface wrinkle defect during the multi-pass hot bar rolling in combination with the finite element analysis. The predicted results using new instability map suggested matched well with the observations obtained from the industry. The developed approach is easy to apply to the available simulation tools to determine necessary processing parameters.

Polymer nanofibers can be generated by a electrospinning process. The process involves electrically charged jet of polymer solutions evolving from a droplet. The jet stretches in vertical direction due to the difference between charged particle and constant current located at the collector, while the Coulomb and viscoelastic forces start to contribute to radial and azimuthal (torsional) stretching. In this paper, the unstable dynamics of the liquid polymer jet is examined experimentally and theoretically. A complex viscoelastic rheological model has been adopted to analyze the behavior of a charged liquid jet. The model includes complex phenomena of stress relaxation of the liquid jet resulting from the competing force components. The experimental data of the jet paths captured by high-speed videocamera also confirm the similar behavior with the predictions.

Stability is a very important part which we must consider in structural design. In this paper, we take advantage of finite element method to study parametrical instability of lattice dome structures, which is subjected to harmonically pulsating load. We consider elastic stiffness and geometrical stiffness simultaneously during the calculation of stiffness matrix, and adopt consistent mass matrix to make the solution more correct. In order to obtain instability regions, we represent displacements and accelerations in dynamic equation by trigonometric series expansions, and then obtain Hill's infinite determinants. After first order approximation, we can get first and second order dynamic instability regions eventually. Finally, we take 24-bar star dome and 90-bar lamella dome as examples to investigate dynamic instability phenomena.

Purpose: This study was to investigate the effect of instability on the activation of lower limb muscles during lunge exercise. Methods: The study subjects were healthy twenties and were selected to have no orthopedic or neurological diseases. 1) Flat lunge exercise (Lunge 1, 2) Lunge exercise on TOGU (Lunge 2, 3) Holding the olympic bar and moving the lunge on TOGU (Lunge 3, 4) Holding the Surge and moving the lunge on TOGU (Lunge 4). Through the above four actions, we can see how the top-down instability influences the lower limb unlike the Bottom-up instability. EMG attachment sites were gluteus medius, vastus medialis, gastrocnemius, tibialis anterior. Results: These result suggest that exercise using Lunge 4 activity was the highest in muscle activity compared to other exercises, but vastus medialis showed the highest muscle activity in Lunge 2 exercise(p<0.05). Conclusion: This study showed the muscular activity of the lower extremities according to the lunge exercise using the instability tools.

The instability curve of a Rijke tube system was obtained accurately by following different paths of heat power and flow-rate for three regions and by defining its locus from the criterion based on the measured sound pressure levels. The unstable limits in the region of flow-rate lower than that at the minimal power are compared with previous data. To observe the effect of turbulence on the unstable limits, inflow turbulence was introduced by placing a bundle of circular cylinders upstream of the heating part ($50<Re_d<700$). The large-amplitude inflow fluctuation may delay the transition of the chamber acoustic mode to the unstable Bone even at a sufficient power.

Paroxysmal autonomic instability with dystonia (PAID) is a rare complication of brain injury. Symptoms of PAID include diaphoresis, hyperthermia, hypertension, tachycardia, and tachypnea accompanied by hypertonic movement. Herein, we present the case of a 44-year-old female patient, who was diagnosed with paraneoplastic limbic encephalopathy caused by thyroid papillary cancer. The patient exhibited all the symptoms of PAID. On the basis that the symptoms were unresponsive to antispastic medication and her liver function test was elevated, we performed alcohol neurolysis of the musculocutaneous nerve followed by botulinum toxin type A (BNT-A) injection into the biceps brachii and brachialis. Unstable vital signs and hypertonia were relieved after chemodenervation. Accordingly, alcohol neurolysis and BNT-A injection are proposed as a treatment option for intractable PAID.

Objective: To determine the associations between ankle instability, breathing metrics, and autonomic symptoms in adults with chronic ankle instability (CAI). Design: Cross-sectional study compliant with the STROBE statement. Methods: Fifty-five adults with CAI were recruited. CAI was defined as a Cumberland ankle instability tool (CAIT) score £25. Outcome measures included CAIT score, weight bearing lunge test (WBLT), Y-balance test (YBT), body oxygen level test (BOLT), self-evaluation of breathing questionnaire (SEBQ), Nijmegen questionnaire (NQ), heart rate variability (HRV; including heart rate [HR], standard deviation of normal-to-normal intervals [SDNN], and root mean square of successive differences [RMSSD]), and composite autonomic symptom score-31 (COMPASS-31). Pearson's correlation coefficients were calculated and simple/multiple linear regression analyses were performed using SPSS (Version 25.0; IBM Corp., Armonk, NY, USA), with a significance level set at 𝛼=0.05. Results: Worse ankle instability (lower CAIT score) was associated with lower BOLT (r=0.373), higher SEBQ (r=-0.507), and higher NQ (r=-0.356). The corresponding regressions yielded, BOLT=8.173+0.416xCAIT, SEBQ=24.213-0.658xCAIT, and NQ=17.456-0.514xCAIT. CAIT was also related to autonomic symptoms; COMPASS-31=23.806-0.690xCAIT. Respiratory-related variables significantly contributed to autonomic dysfunction; COMPASS-31=2.269+0.456xSEBQ+0.398xNQ. SDNN was correlated with HR (-) and RMSSD (+), but not with the other variables. Conclusions: In adults with CAI, greater ankle instability is associated with impaired breathing control and increased burden of autonomic symptoms. These findings suggest a potential link between mechanical ankle instability and autonomic imbalance in which diaphragmatic dysfunction may be an important factor. Future studies are required to determine whether the incorporation of diaphragm-focused breathing interventions are beneficial for autonomic stabilization and functional recovery in individuals with CAI.

Background: During daily activities, stability is maintained to enhance the function of muscles surrounding the lumbopelvic and hip structures. The core muscles such as the rectus abdominis (RA), external oblique (EO), and internal oblique (IO) responsible for this stability. One effective static exercise for strengthening these muscles is the plank. Objects: This study aimed to compare abdominal electromyographic activation when an unstable support surface was applied to the upper and lower extremities during a standard and a knee plank. Methods: A total of 30 adults (15 males and 15 females) participated in this study. Surface electromyography electrodes were placed on the RA, EO, and IO muscles. Data were collected under six conditions for males, including two plank postures (standard and knee planks) and three unstable surface conditions (a dynamic balance cushion applied to the upper extremities, lower extremities, or no cushion). Female participants performed only the knee plank. A mixed-effects model with a random intercept was used to analyze muscle activation across plank posture and surface position, with statistical significance set at α = 0.05. Results: In males, the standard plank elicited greater muscle activation than the knee plank across all muscles (p < 0.0001). Additionally, applying an unstable support surface to the upper extremities significantly increased muscle activation in both plank postures in EO and IO (p < 0.001). Other muscle, RA, was only affected by the unstable support surface in the standard plank position only. In females, the knee plank with upper limb instability resulted in the highest muscle activation for all muscles. Conclusion: These findings highlight the importance of surface instability in core muscle engagement. However, future studies should further investigate abdominal muscle activation with a more detailed analysis and the inclusion of a control group to enhance comparative validity.

Background: Lumbar segmental instability is commonly assessed using sagittal translation (ST) and segmental angulation (SA) on flexion-extension radiographs, but their associations with paraspinal muscle morphology in lumbar spinal stenosis (LSS) remain unclear. Objects: To examine the associations between continuous ST/SA measurements, left-right paraspinal muscle cross-sectional area (CSA) asymmetry and total CSA at L4-5 in patients with LSS, controlling for age, sex, and body mass index (BMI). Methods: Eighty-five patients with LSS were included. The ST (mm) and SA (°) at L4-5 were measured from flexion and extension views. CSA of the paraspinal muscle was measured on magnetic resonance imaging at the L4-5 mid-disc level. CSA asymmetry was defined as right - left and total CSA as right + left. Partial correlations between ST/SA and CSA were calculated after controlling for age, sex, and BMI. Results: Forty-seven female and 38 male were included. The mean ST and SA were 2.15 ± 1.58 mm and 8.80° ± 5.51°, respectively. ST was weakly correlated with SA (partial r = 0.260, p < 0.05). ST showed a weak positive correlation with erector spinae (ES) CSA asymmetry (partial r = 0.223, p < 0.05) but was not associated with psoas major or multifidus asymmetry or total CSA in any muscle. SA was not associated with CSA asymmetry or the total CSA. Conclusion: In patients with LSS, ST at L4-5 was weakly but significantly correlated with ES CSA asymmetry after controlling for age, sex, and BMI. In contrast, SA showed no significant association with paraspinal muscle CSA asymmetry or total CSA, and neither ST nor SA was significantly associated with the total CSA of the paraspinal muscles. ST and SA were weakly correlated, suggesting that translational and angular motions represent partly distinct components of segmental motion in this cohort.

Objective: The purpose of this study was to compare the muscle activity of the vastus lateralis, vastus medialis, rectus femoris, and gluteus medius muscles according to the medial/lateral bias of the knee during lunge exercise. Design: Crossed-control group study Methods: This study recruited 20 healthy men and women in their 20s who were capable of lunge exercise and had no musculoskeletal or neurological abnormalities. All three postures were performed three times each during lunge exercise. In each posture, surface electromyography (EMG) equipment was used to measure muscle activity of the vastus lateralis, vastus medialis, rectus femoris, and gluteus medius during lunge exercise. Results: As a result of comparing lower extremity muscle activity in normal, medial and lateral knee-deviation postures according to lunge exercise, the muscle activity of the vastus medialis was 107.09±13.90% in the normal posture, 79.24±5.26% in the medial- deviation posture and 125.73±14.30% in the lateral- deviation posture, which was a statistically significant difference (p<0.05). However, In the case of the vastus lateralis, rectus femoris and gluteus medius there was no statistically significant difference in muscle activity in the medial and lateral deviation positions(p>0.05). Conclusions: As a result, it was found that the muscle activity of the vastus medialis during lunge exercise significantly increased in the lateral deviation posture compared to the normal and medial deviation postures. In the case of the vastus lateralis, rectus femoris and gluteus medius there was no significant difference in muscle activity for medial and lateral knee deviation.

Objective: To compare ankle dorsiflexion range of motion (ROM) and dynamic balance performance during the Y-Balance Test (YBT) between individuals with and without Chronic Ankle Instability (CAI), as classified by the cumberland ankle instability tool (CAIT). Methods: A cross-sectional study was conducted among 20 adult recreational badminton players. Participants were classified into a CAI group (n = 10) with CAIT scores <24 and a non-CAI group (n = 10) with scores ≥24. The YBT was used to assess dynamic balance and dorsiflexion ROM. Ankle dorsiflexion angles were analyzed using 2-D video analysis with reflective markers and Kinovea software. Independent t-tests were used to analyze between-group differences in ankle dorsiflexion ROM and normalized reach distances, with the level of significance set at p < 0.05. Results: The independent t-tests revealed no statistically significant differences in ankle dorsiflexion ROM between the CAI group and the non-CAI group for in the anterior (p > 0.05), posteromedial (p > 0.05), or posterolateral (p > 0.05) directions. Similarly, there were no significant differences in normalized maximum reach distances and composite YBT score between the two groups (p > 0.05). Conclusion: This study found that individuals classified as having CAI by the CAIT questionnaire showed no significant differences in ankle dorsiflexion or dynamic balance performance during the YBT. These results suggest that the dorsiflexed position during the YBT may enhance joint stability and obscure functional deficits related to ankle instability. Therefore, clinicians shoulder consider using functional assessment with appropriate caution to better detect impairments associated with CAI based on these results.

Thermo-acoustic instability of methane/ air flames in an industrial gas-turbine combustor is numerically investigated adopting CFD analysis. The combustor has 37 EV burners through which methane and air are mixed and then injected into the chamber. First, steady fuel! air mixing and flow characteristics established by the burner are investigated by numerical analysis with single burner. And then, based on information on the flow data, the burners are modeled numerically via equivalent swirlers, which facilitates the numerical analysis with the whole combustion system including the chamber and numerous burners. Finally, reactive flow fields within the chamber are investigated numerically by unsteady analysis and thereby, spontaneous instability is simulated. Based on the numerical results, scaling analysis is conducted to find out the instability mechanism in the combustor and the passive control method to suppress the instability is proposed and verified numerically.

Background: Ankle sprains occur frequently among humans who undertake various body movements. Diverse walking environments and dual tasks, that can affect ankle sprains, have been studied. However, there is a lack of research on inter-trial variability according to the changes in gait speed. Objects: The purpose of this study was to compare the adaptive ability of walking between the subjects with chronic ankle instability and healthy adults while performing a walking task with different walking speeds. Methods: In this study, 24 people in the chronic ankle instability group and 24 people in the healthy ankle group were selected as subjects. The length of the pre-measurement and the actual walking measurement were both set to 4.6 m. Once the subjects entered the measurement section, they changed their gait speed according to the randomly assigned speed change. Gait was measured twice and the average value was used for the analysis. Results: The coefficient of variation (CV) of cycle time in subjects with chronic ankle instability showed a significant difference in all cases except when the subjects changed their speed from preferred to slow and from slow to preferred. The CV of step length demonstrated a significant difference in all cases except for the change from slow to preferred and from preferred to fast. The cycle time and step length differential showed a significant difference only when the subjects changed the speed from slow to fast. Conclusion: The subjects with chronic ankle instability were found to have significantly reduced walking adaptability while performing inter-trial variability tasks with different gait speeds compared to healthy subjects.

Objective: The purpose of this study was to investigate effects of taping technique applied to knee instability. Design: Cross sectional study. Methods: Twenty-six participants with knee instabilityparticipated in this study. They were randomly assigned to the Kinesio taping (KT) group (n=13) and the dynamic taping (DT) group (n=13). Both groups applied knee stabilization taping techniques. In order to compare the effects of each taping technique, the change in the landing error scoring system (LESS) and lower extremity joint angle wasrecorded before and after the intervention. Results: Both groups significantly decreased in the change before and after the LESS (p<0.05). At the joint angle of the lower extremities, KT group significantly reduced the valgus angle at the max knee flexion (p<0.05). In DT group knee joint flexion and hip joint flexion angles were significantly increased at foot contact (p<0.05). In max knee flexion, the knee joint flexion angle was significantly increased (p<0.05). In foot contact, max knee flexion, the knee joint valgus angle was significantly increased (p<0.05). DT group showed more significant changes in knee joint flexion angle at foot contact and hip joint flexion angle at max knee flexion. Conclusions: Dynamic taping is a clinically applicable intervention method for lowering the risk of non-contact injury in participants with knee instability and for knee stability during rehabilitation exercises.

Background: There are many factors contributing to chronic ankle instability (CAI), but recently it has been reported that dynamic balance, peroneal reaction time, and eversion strength deficiency are highly related. Purpose: The purpose of this study was to find out whether the contributing factors of ankle instability were used in rehabilitation interventions and, if so, whether they were effective. Study design: Systematic review Methods: Relevant health databases, such as PubMed, MEDLINE, CINAHL and ScienceDirect, were searched. Systematic reviews were included if they fit the research question, and they were clearly defined by the search strategy criteria. Results: A total of 58 articles were retrieved and 19 articles fulfilled inclusion criteria. In duplicate counts, dynamic balance training (DBT) was used as an intervention in 15 studies, and strength training (ST) was used in 4 studies. There were also mixed forms of intervention that made it difficult to divide exercise methods. Conclusions: DBT and ST improved the ankle strength, balance, functional performance, and self-reported function of CAI patients. There was limited evidence that either DBT or ST was more effective in improving function in CAI patients.

Objective To compare the effect of foot orthotics and rehabilitation exercises by assessing balancing ability and joint proprioception in athletes who have chronic ankle instability. Methods Forty-one athletes who visited hospitals due to chronic ankle instability were randomly assigned to two groups. One group had ankle rehabilitation exercises while the other group had the same rehabilitation exercises as well as foot orthotics. Joint position sense of the ankle joint was examined by using an isokinetic exercise machine. Balancing abilities categorized into static, dynamic and functional balance abilities were evaluated by using computerized posturography. We tested the subjects before and after the four-week rehabilitation program. Results After the four-week treatment, for joint reposition sense evaluation, external 75% angle evaluation was done, revealing that the group with the application of foot orthotics improved by -1.07±1.64 on average, showing no significant difference between the two groups (p>0.05). Static, dynamic and functional balancing abilities using balance masters were evaluated, revealing that the two groups improved in some items, but showing no significant difference between them (p>0.05).Conclusion This study found that athletes with chronic ankle instability who had foot orthotics applied for four weeks improved their proprioceptive and balancing abilities, but did not show additional treatment effects compared with rehabilitation exercise treatment.

Objective: The purpose of this study was to find out how the back instability during clam exercise (CE) causes changes in pelvic rotation and hip joint abductor muscle activity, and to find out the effects with different methods of application of pressure biofeedback. Design: Comparative study using repeated measures. Methods: Each subjects performed the clam exercise (CE) without pressure biofeedback, the clam exercise with pressure biofeedback applied to the back (CE-PBU to back), and the clam exercise with pressure biofeedback applied to the side (CE-PBU to side). The amount of pelvic rotation was measured using myomotion. And the muscle activity of the muscle gluteus medius and the tensor fasciae latae was measured using EMG device. One-way repeated measures ANOVA followed by the Bonferroni post test were used to compare the EMG activity in each muscle and pelvic rotation angle during the CE, CE-PBU to back, CE-PBU to side. Results: The amounts of pelvic rotation was the lowest in CE-PBU to back (p< 0.05) and the ratio of muscle activity of the muscle gluteus / tensor fasciae latae was the highest in CE-PBU to back (p< 0.05). Conclusions: It is thought that, in order to stabilize the waist-pelvis and increase hip joint muscle strength in subjects with back instability, applying clam exercise with pressure biofeedback applied to the lower back is effective in improving waist-pelvic movements and selectively strengthening the muscle gluteus medius.