Earticle

일반적으로 모발에 웨이브를 형성시키기 위해서 시술하는 퍼머넌트 웨이브 중에서도 가장 자연스럽고 탄력 있는 웨이브를 얻기 위해서 열을 이용한 시술을 선호한다. 이에 본 연구는 퍼머넌트 웨이브 시술시 사용되는 로드의 열 형성도에 따라서 모발에 미치는 표면적인 모발의 손상도를 주사전자현미경을 활용하여 측정하였다. 로드의 열 형성이 웨이브에 미치는 영향력을 알아보기 위해 열 로드에서 전달되는 온도를 측정하고 웨이브를 시술하여 웨이브 된 둥근 모양의 형태대로 모발을 절단한 후 처치를 하였다. 주사전자현미경 관찰에서 뜨거운 열이 직접적으로 닿은 부분은 모발이 끊어진 것을 확인할 수 있었는데 끊어진 면이 매끄러운 현상을 보였다. 본 연구의 결과로는 퍼머넌트 웨이브시에 사용되는 열 로드는 열 전달이 로드 전체에 고르게 전달되는 특성을 가지고 있는 재질을 활용하고 로드 의 구조 또한 중요함을 인식하고 미용 업계에서 활발한 연구가 이뤄져야 할 것으로 사료된다.

In general, heat-based treatments are preferred to form the most natural and elastic curls. Therefore, this study measured the degree of hair damage, which has an influence on hair, in relation to the heat formation of the rods used during perms using a scanning electron microscope (SEM). To examine the influence of the heat formation rods on permanent waves, this study measured the temperature transmitted from such rods. Then, a treatment was given after cutting the hair according to the round shape. According to observation with a SEM, hair breakage was found in the portion in direct contact with the heat, and the broken surface was smooth. According to the study results, it is anticipated that there should be many studies on the rods used during perms in the consideration of their structure and importance using materials that have the property of even heat transmission.

FRP(Fiber Reinforced Polymer)는 부식의 저항성, 고강도, 피로저항 능력 및 성형성 등에서 우수한 건설 신소재이다. 광섬유 브래그 격자(Fiber Bragg Grating; FBG) 센서는 전자기 저항, 작은 소재의 크기, 그리고 높은 내구성 등의 이점으로 smart sensor로서 현재 많이 사용되고 있다. 하지만 FBG 센서의 변위 측정 기술 능력의 부족으로 현재까지는 변형률, 온도 등의 물리량 측정센서로서 활용되고 있는 실정이다. 본 연구에서는 FRP와 FBG센서의 기능 복합화(Hybrid)를 통하여 smart FRP Rod를 개발 한 후 인장시험을 실시하였다. 또한, FBG센서에 의해 측정된 변형률 데이터를 신경망(Neural Network) 기법을 이용하여 변위 추정 모형을 개발함으로서 FBG 센서 단점인 변형률 계측만을 위한 센싱 역할을 극복하고자 한다. 인공신경망 모형은 MLP(Multi-layer Perceptron)로, 오차범위 0.001에 수렴 될 수 있도록 학습(training)을 실시하였다. 학습에는 비선형 목적함수와 역전파 학습(Back-propagation) 알고리즘을 적용하였으며 모형의 검증은 UTM에서 측정된 변위 값과 수치해석에 의한 결과 값을 비교함으로서 실시하였다.

FRP (Fiber Reinforced Polymer) is an excellent new constructional material in resistibility to corrosion, high intensity, resistibility to fatigue, and plasticity. FBG (Fiber Bragg Grating) sensor is widely used at present as a smart sensor due to lots of advantages such as electric resistance, small-sized material, and high durability. However, with insufficiency of measuring displacement, FBG sensor is used only as a sensor measuring physical properties like strain or temperature. In this study, FRP and FBG sensors are to be hybridized, which could lead to the development of a smart FRP rod. Moreover, developing the estimated model for deflection with neural network method, with the data measured through FBG sensor, could make conquest of a disadvantage of FBG sensor - uniquely used for sensing strain. Artificial neural network is MLP (Multi-layer perceptron), trained within error rate of 0.001. Nonlinear object function and back-propagation algorithm is applied to training and this model is verified with the measured axial displacement through UTM and the estimated numerical values.

북아이오와주립대학 도서관은 우수한 교양 커리큘럼을 지원하는 개별화 학습 환경과 다양한 지적, 문화적 커뮤니티를 지원하는 것을 사명으로 하고 있다. 1987년부터 전략적 계획을 수립하기 시작하여 현재 5년 단위로 전략적 계획을 수립하고 있으며, 최근 전략이 어느 정도 달성되고 있는가에 대한 성과측정의 필요성이 제기되었다. 이에 본 연구는 북아이오와주립 대학도서관의 최근 전략적 계획 2004-2009의 내용을 분석하여 전략을 균형성과표의 네 관점으로 전환하는 BSC 모형과 전략지도를 개발하였다. 이와 함께 각 관점별 전략적 목적을 측정하는 핵심성과측정지표와 이를 이끄는 동인들의 인과관계 모형을 개발하여 제시하였다.

The University of Northern iowa Rod Library has mission statement that a personalized learning environment founded on the strong liberal arts curriculum and to supporting an intellectually and culturally diverse community. The Rod Library has been developing the strategic plans by 5 years since 1987 Recently, the strategy has been faced need to measure of performance how much does make it up. This study developed the BSC model and the strategy map that analyze the strategic plan 2004-2009 of the University of Northern iowa Rod library and transfer the strategy into the four perspectives of BSC. In addition, this study presented the success performance indicators measuring the strategic goals of each perspectives and the cause-effect model driving the lead indicators of performance.

A nuclear fuel rod support grid is an important structural part of a nuclear fuel assembly which is used in a pressurized light water reactor. It provides a flexible support for the nuclear fuel rods which experience a severe thermal expansion and a contraction caused by the harsh operational conditions in the core of a reactor. Diverse design requirements should be set for the performances of the multidisciplinary natures such as an impact resistance, spring characteristics, possible amount of a fretting wear on the fuel rods, the coolant flow and heat transfer around it, and so on. In this paper, an effort is reported to improve the impact resistance of an OPT-H type support grid, a high performance spacer grid developed by the Korea Atomic Energy Research Institute. A systematic approach by using an axiomatic design and optimization is utilized for this purpose.

A rolling speed dependent spread model is proposed for predicting the exit cross sectional shape in oval-round (or round-oval) pass rod rolling process when the rolling speed is very high. The effect of rolling speed on the exit cross sectional shape is measured by performing a four-pass continuous high speed (${\sim}80m/s$) rod rolling test and is described in terms of the spread correction parameter. The validity of the model is examined by applying it to rod rolling process at POSCO No.3 Rod Mill. The cross sectional shapes of workpiece predicted by the proposed model coupled with the surface profile prediction $method^{6}$ are in good agreement with those obtained experimentally.

The lateral flow in the sub-channel of a nuclear rod bundle increase turbulent mixing and enhance heat transfer rate and safety. Various types of mixing vanes have been investigated to produce more lateral flow. In this study, the thermal-hydraulic characteristics of Hybrid mixing vane in a 17x17 rod bundle were calculated. Hybrid mixing vane has bended root part and split stem part. The computation was performed using a supercomputer due to the high number of grid meshes. The characteristics of Hybrid mixing vane were compared to Split mixing vane. The Hybrid mixing vane showed higher values of secondary intensity, cross-sectional turbulence intensity and Nu number and lower values of maximum temperature and standard deviation of temperature. Meanwhile, The Hybrid mixing vane has higher invariance because small vortexes travel, stretch and are connected with main stream.

Phosphate coating is applied to the surface of the round bar material used in the multi-stage cold forging process for the purpose of lubrication. The film characteristics are determined according to the conditions of the phosphate film treatment process. In this study, the film properties according to the phosphate treatment conditions were defined as the coefficient of repeated friction and quantitative analysis was performed. Different friction behaviors were exhibited depending on the film properties, suggesting that optimization of the phosphate film treatment conditions is possible based on this. Finally, as a practical example, friction behavior according to the film characteristics was applied to the automotive engine bolt forming process. As a final conclusion, the need for linkage analysis with phosphating conditions for optimizing the forging process was raised. In addition, it can be seen that damage to the phosphate film should be considered in the process of predicting the limiting life of the die.

A wire rod, a material for multistage cold forging, is subjected to spheroidization and low annealing heat treatment to secure formability, and a phosphate coating treatment on the material surface to secure lubricity. The film layer produced by the phosphate treatment process is involved in adhesion to the material surface, adhesion to the forging die surface, and lubricity. This results in the increase or decrease of the forming load and the increase or decrease of the die life in the cold forging process. In particular, as the cold forging process progresses, the phosphate film is damaged and the original performance is deteriorated, so there is a high possibility of process defects. In case of excessive damage, the film is completely lost and die soldering occurs. Therefore, in this study, quantitative criteria for phosphate film damage are presented and the effect on the cold forging process is analyzed based on this to improve process analysis prediction accuracy. Therefore, in this study, quantitative criteria for phosphate film damage are presented, and based on this, the friction coefficient in the multi-stage cold forging process is to be derived.

본 연구에서는 기존 철근콘크리트 건물의 보-기둥 접합부의 내진성능의 개선을 위해 외부 보-기둥 접합부 영 역을 FRP보강재(매입형 CFRP Rod, CFRP시트, 아라미드섬유시트)를 사용하여 복합 보강한 후 내진성능을 평 가하였다. 총 5개의 실험체를 제작하고 실험을 수행하여 내진성능을 평가하였으며, 본 연구의 실험결과를 근 거로 다음과 같은 결론을 얻었다. 기존 철근콘크리트 외부 보-기둥 접합부의 접합부 영역을 보강한 결과, 초기 재하시 접합부 영역의 균열억제 효과와 재하 전 과정을 통하여 보강재의 구속효과로 인하여 균열억제 효과가 커서 안정적인 파괴형태 및 내력 향상 효과를 나타내었다. 매입형 CFRP Rod와 CFRP시트, 아라미드섬유시트를 복합 보강한 RC 외부 보-기둥 접합부 실험체 RBCJ- SRCB 시리즈, RBCJ-SRA3는 표준실험체 RBCJ와 비교하여 변위연성3에서 최대 내력은 각각 2.12, 2.00배 증 가하였고, 에너지소산능력은 변위연성5에서 각각 1.90, 1.65배 증가하였다.

In this study, experimental research was carried out to evaluate and improve the seismic performance of reinforced concrete beam-column joint regions using hybrid retrofitting with the various materials (embedded FRP Rod, CFRP sheet, and Aramid fiber sheet) in existing reinforced concrete building. Therefore it was constructed and tested five specimens retrofitting the beam-column joint regions using such retrofitting and materials. Specimens, designed by hybrid retrofitting the beam-column joint regions of existing reinforced concrete building, were showed the stable failure mode and increase of load-carrying capacity due to the effect of crack control at the times of initial loading and confinement of retrofitting materials during testing. Specimens RBCJ-SRCB series, RBCJ-SRA3 designed by the hybrid retrofitting with embedded FRP Rod, CFRP Sheet, and Aramid fiber sheet in reinforecd beam-column joint regions were increased its maximum load carrying capacity each by 2.12, 2.00 times and its energy dissipation capacity each by 1.90, 1.65 times in comparison with standard specimen RBCJ for a displacement ductility of 3, 5.

This study examines how much the radiation dose rate around it varies if a crack occurs on the spent nuclear fuel rod. Thespent nuclear fuel rod to be examined is that of Kori unit 3&4. The source terms are evaluated using the ORIGEN-ARPthat is part of the version 5.1 of the SCALE package. The radiation dose rate is assessed using the TORT. To check if thestructure of a fuel rod is appropriately modeled in the TORT calculation, the calculation results by the TORT arecompared with those by the ANISN for the same case. From the code simulation, it is known that if a crack occurs on thespent nuclear fuel rod, the neutron dose rate varies depending on what material is the crack filled with, but the gammadose rate varies irrespective of type of the material that the crack is filled with.

Background: Surface soil radiation monitoring around nuclear facilities is important to classify and characterize the contaminated areas. A scanning and direct measurement technique can survey the sites rapidly before starting sampling analysis. Materials and Methods: Regarding this, we test and suggest a measurement technique for gross alpha/beta and 90Sr activities in surface soil based on a mobile ZnS(Ag)/PVT (polyvinyltoluene) array and a handheld PVT rod, respectively. To detect 90Sr selectively in soil mixed with naturally occurring radioactive materials, chosen energy channel counts from the multichannel analyzers were used instead of whole channel counts. Soil samples contaminated with exempt liquid 90Sr with 1 Bq· g-1, 3 Bq· g-1, and 10 Bq· g-1 were prepared and hardened by flocculation. Results and Discussion: The mobile ZnS(Ag)/PVT array could discriminate gross alpha, gross beta, and gamma radiation by the different pulse-shaped signal features of each sensor material. If the array is deployed on a vehicle, the scan minimum detectable concentration (MDC) range will be about 0.11–0.17 Bq· g-1 at 18 km·h-1 speed, highly sensitive to actual sites. The handheld PVT rod with 12 mm (Φ) × 20 mm (H) size can directly measure 90Sr selectively if channels on which energies are from 1,470 and 2,279 keV are gated, minimizing crossdetection of other radionuclides. These methods were verified by measuring soil samples fabricated with homogeneous 90Sr concentrations, showing static MDC of 2.16 Bq· g-1 at a measurement time of 300 seconds. Conclusion: Based on the results, comprehensive procedures using these detectors are suggested to optimize soil sites survey.

This study presents the development of a magnetostrictive control rod position indicator (Mag-CRPI) for improving safety of nuclear power generation. Mag-CRPI principle is based on two magnetostrictive effects: The Wiedemann effect and the Villari effect. The position may be estimated by multiplying time-of-flight (TOF) of the elastic wave from the cursor magnet to the sensing coil, and a sound speed of the magnetostrictive wire. A Mag-CRPI prototype has been designed and built. Experiments are conducted to characterize the Mag-CRPI. Change of the TOF is obtained with cursor magnet movement interval of 100 mm. Averaged position error is estimated to be 0.002m over the entire measuring length. Based on experimental results, the performance of Mag-CRPI is validated, thereby confirming feasibility of a nuclear reactor-internal control rod.

This paper presents a cable-driven hydraulic actuator named Cable Rod Hydraulic Actuator (CRHA). The cable actuating system is attractive for designing a compact joint in robotic applications since it can be installed remotely from the joint. Recently, cable rods have been used in pneumatic area for inertia reduction. However, designing cable rods in hydraulics is challenging because it is difficult to achieve flexibility and endurance simultaneously under high pressure conditions. In this paper, the cable rod, which consists of a cable and jacket, is proposed to meet both requirements. To design the CRHA, we determined the design parameters, such as cylinder size, and selected the cable rod's material by friction and leakage test. Finally, comparisons experiments about step and frequency responses with conventional hydraulic actuators were performed to assess feasibility for robotic joints, and the results show that the proposed system has good bandwidth and fast response as robotic joints.

Putting a conductive rod between rotating axial electrodynamic wheels composed of repetitive permanent magnets, three-axial magnetic forces generate on the conductive rod. It is possible to levitate and transfer the rod on space with the forces. However, the forces vary in direction and magnitude for a position of the rod between the electrodynamic wheels. Thus, the position influences the stability of the rod also. To guarantee the stability of a levitated object, the force acting on the object should have negative stiffness like a spring. So, we analyze the stable operating range of the conductive rod levitated by the axial wheels with the commercial finite element tool in this paper. Specially, as the pole number and the radial width of permanent magnets has much influence on the generated force and thereby the stable region, their sensitivities are analyzed also. The analytic result is compared with experimental result.

A proposed hybrid self-tuning control scheme for single rod hydraulic cylinder which has varying loads is presented here. An adaptive controller is developed for the system that use feedforward and P feedback control for simultaneous parameter identification and tracking control. Through experimental results, the performance comparison of the hybrid self-tuning controller with a constant gain P contro- ller clearly shows its superior ability in handling load changes in quiescent states.

A PID controller integrated with a velocity feedback is designed for fluid power elevator model system in this study. In this case, for outside disturbance load a hydraulic cylinder and a pressure control valve are used. In this method overshoot is reduced and settling time becomes also shorter than the values achieved from the PID controller system only In conclusion a PID controller integrated with a velocity feedback is considered a suitable control method for fluid power elevator system.

Aluminum casting/forging process is used to produce an aluminum tie-rod end for the steering system of automobiles. Firstly, casting experiments were carried out to get a good preform for forging the tie-rod end. In the casting experiment, the effects of additives, Ti+B, Zr, Sr, and Mg, on the mechanical properties and the microstructure of a cast preform were investigated. And a finite element analysis was performed to determine an optimal configuration of the cast preform. Lastly, a forging experiment was carried out to make the final product of aluminum tie-rod end by using the above cast preform. In the casting experiments, when 0.2% Ti+B and 0.25% Zr were simultaneously added into molten Al-Si alloy, the highest values of tensile strength and elongation of the cast preform were obtained. When 0.04% Sr were added into the molten aluminum alloy, the finest silicon-structure was observed in the cast preform. The highest hardness was obtained when 0.2% Mg was added. In the forging experiment, It was confirmed that the optimal configuration of a cast preform predicted by FE analysis was very useful. The hardness of a cast/forged product using designed preform was superior to that of required specification.

Unlike the drawing of round section from round bar, the shaped drawing like polygonal section is known to have influence not only drawing stress but also corner filling. Therefore. this study analyze the drawing process of suqare rod from round bar using nonsteady state rigid-plastic FEM. To investigate effects of process variables of the drawing process of square rod from round bar, FE-simulations with variety of reduction in area and semi-die angle for a given frictional condition have been conducted. By this results, it has to suggest optimal process condition on the drawing stress and the corner filling. In addition, it has determined forming limit considering necking and bulging.