Earticle

모바일 기기는 이제 한 사람에 대한 개인 소유물로 자리잡았으며 이를 이용하여 서로 다른 컴퓨팅 환경에서 이루어지는 다양한 서비스를 관리하고 제공받는다. 또한, 서비스 영역이 넓어짐에 따라 서비스 종류와 개인이 이용하는 서비스 수는 증가한다. 따라서, 본 논문에서는 모바일 환경에서 가입된 서비스를 제공받고 관리함으로써 효율성을 증대 시키기 위해 사용자가 관리 가능한 다중 서비스 통합 시스템에 관한 시뮬레이션 프로그램 설계에 관하여 연구하였다. 이를 위해, 시간 그래프 메커니즘과 디바이스를 사용해서 어플리케이션 Prototype을 구현하는 방법에 대해 연구, 제안 하였다.

Mobile devices have now become personal possessions for one person. And various services managed in different computing environments are managed and provided. Also, as the service area becomes wider, the number of services and the number of services used by individuals increase. Therefore, in this paper, we study the design of a simulation program for a multi-service integrated system that can be managed by a user in order to increase the efficiency by subscribed services in mobile environment. To do this, we have proposed and proposed a method to implement application prototype using time graph mechanism and device.

산업자동화의 고정밀도에 따라 강인한 제어가 요구되고 있다. 하지만 PID 제어기를 갖는 전동기 시스템이 부 하 외란을 받게 되면 제어시스템의 강인 제어는 어렵게 된다. 이에 대해 보완적인 한 방법으로 본 논문에서는 전동기 제어 시스템을 위한 PID-전문가 복합형 제어 기법을 제시하였다. 만약 PID 제어 시스템이 안정한 상태에 있다면 전문 가 제어기는 사용되지 않는다. 그러나 오차가 일단 발생하게 되면, 전문가 제어기는 오차를 구속 영역 내로 들어가도록 제어한다. 이에 따라 외란의 영향은 현저히 감소하게 된다. PID-전문가 복합형 제어기를 이용한 직류 서보 전동기의 강인성을 시뮬레이션에 의해 확인하였다.

Robust control for DC motor is needed according to the highest precision of industrial automation. However, when a motor control system with PID controller has an effect of load disturbance, it is very difficult to guarantee the robustness of control system. In this paper, PID-Expert hybrid control method for motor control system as a compensation method solving this problem is presented. If PID control system is stable, the Expert controller is idle. if the error hits the boundary of the constraint, the Expert controller begins operation to force the error back to the constraint set. The disturbance effect decrease remarkably, robust speed control of DC motor using PID-Expert Hybrid controller is demonstrated by the simulation.

요즘과 같이 바쁜 현대사회에서는 다수의 학생들과 직장인들이 상당한 시간동안 의자에 앉아서 일과를 보내는 데, 이 때 올바른 자세를 유지하지 않아 척추 측만증이나 요통증후군, 척추사이원반 탈출증과 같은 질병들이 발생합니 다. 그래서 우리는 일상생활에 사용 할 의자의 등받이 부분을 개인의 척추 모양에 맞는 등받이를 3D 프린터로 제작하 여 척추 측만을 교정하고 척추 질병을 예방 할 수 있는 3D척추교정의자를 제작하게 되었다.

In modern society, a large number of students and workers spend a lot of time sitting in chairs and not working properly, resulting in diseases such as scoliosis, back pain syndrome, and intervertebral disc prolapse. So we made a 3D printer for the back of the chair that would be used for everyday life, and made a 3D spinal column chair that can correct the spine and prevent spinal diseases.

Two circularly polarized antenna arrays, which reduce two redundant OAM modes, are proposed in this paper. One antenna array is composed of 8 right-handed circularly polarized (RHCP) antennas and radiates OAM mode l in x component, OAM mode l in y component and OAM mode (l+1) in z component. The other antenna array has 8 left-handed circularly polarized (LHCP) antennas and transmits OAM mode l in x component, OAM mode l in y component and OAM mode (l-1) in z component. The RHCP and LHCP antenna arrays produce OAM waves with fewer redundant OAM modes compared to the traditional single-direction antenna array. The feed excitations of the two circularly polarized antenna arrays have the same feeding system, which includes power dividers and phase shifters. The reflection coefficient parameters, radiation patterns and phase distributions are measured to display the radiated characteristics of the two proposed methods. Both the simulation and the experimental results demonstrate the effectiveness of the proposed methods.

Recently, methodologies for developing brain-computer interface (BCI) games using the BCI have been actively researched. The existing general framework for processing brain waves does not provide the functions required to develop BCI games. Thus, developing BCI games is difficult and requires a large amount of time. Effective BCI game development requires a BCI game framework. Therefore the BCI game framework should provide the functions to generate discrete values, events, and converted waves considering the difference between the brain waves of users and the BCIs of those. In this paper, BCI game frameworks for processing brain waves for BCI games are proposed. A variety of processes for converting brain waves to apply the measured brain waves to the games are also proposed. In an experiment the frameworks proposed were applied to a BCI game for visual perception training. Furthermore, it was verified that the time required for BCI game development was reduced when the framework proposed in the experiment was applied.

Based on Banach fixed point theorem, a method to calculate nonlinear superposition for three interacting Stokes' waves is proposed in this paper. A mathematical formulation for the nonlinear superposition in deep water and some numerical solutions were investigated. The authors carried out the numerical study with three progressive linear potentials of different wave numbers and succeeded in solving the nonlinear wave profiles of their three wave-interaction, that is, using only linear wave potentials, it was possible to realize the corresponding nonlinear interacting wave profiles through iteration of the method. The stability of the method for the three interacting Stokes' waves was analyzed. The calculation results, together with Fourier transform, revealed that the iteration made it possible to predict higher-order nonlinear frequencies for three Stokes' waves' interaction. The proposed method has a very fast convergence rate.

This paper presents a novel knock imaging technique for human-to-things interfaces. It allows any object to use its own surface as an imaging sensor. The methodology is to sense the structural bending waves caused by the knock and reconstruct the intensity image through the beamforming of the wave signals. To verify this, we prepare a thin piezoelectric sensor array on a square plate. The performances are evaluated by measuring the beam peak, beamwidth, and sidelobe level in the reconstructed image. Finally, a real finger knock test is demonstrated, showing an image reconstruction that the position error is only 3 mm.

The continuous wavelet transform (CWT) has a frequency-adaptive time-frequency tiling property, which makes it popular for the analysis of dispersive elastic wave signals. However, because the time-frequency tiling of CWT is not signal-dependent, it still has some limitations in the analysis of elastic waves with spectral components that are dispersed rapidly in time. The objective of this paper is to introduce an advanced time-frequency analysis method, called the dispersion-based continuous wavelet transform (D-CWT) whose time-frequency tiling is adaptively varied according to the dispersion relation of the waves to be analyzed. In the D-CWT method, time-frequency tiling can have frequency-adaptive characteristics like CWT and adaptively rotate in the time-frequency plane depending on the local wave dispersion. Therefore, D-CWT provides higher time-frequency localization than the conventional CWT. In this work, D-CWT method is applied to the analysis of dispersive elastic waves measured in waveguide experiments and an efficient procedure to extract information on the dispersion relation hidden in a wave signal is presented. In addition, the ridge property of the present transform is investigated theoretically to show its effectiveness in analyzing highly time-varying signals. Numerical simulations and experimental results are presented to show the effectiveness of the present method.

Purpose: The purpose of this study is to analyze the brain waves and develop various exercise programs to improve the physical and mental aspects of stroke patients when neurological physical therapy and sitting table tennis exercise are applied to stroke patients. Methods: In this study, an experiment was conducted on 15 patients diagnosed with stroke, and training was performed after changing the ping-pong table to a sitting position to apply ping-pong exercise to stroke patients. After training was conducted for 40 minutes twice a week for 4 weeks, brain waves were measured before and after. EEG was measured using Laxtha's DSI-24 equipment as a measurement tool, and data values were extracted through the Telescan program. Results: Most of the relative beta waves showed a significant difference before and after the intervention. As for the characteristics of beta waves, this result can be seen as being highly activated during exercise or other activities. Conclusion: Ping-pong exercise in a sitting position is a good intervention method for stroke patients, and it can help to use it as basic data in clinical practice by showing brain activity.

한파는 극한 기후 현상으로 노인에서 치매를 유발하는 중요한 환경 요인으로 제기되고 있다. 그러나 한파가 치매 이환에 미치는 영향의 지역별 차이를 분석한 선행연구는 제한적이다. 지리적 기반 없이 특정 병원 환자군 중심의 임상 코호트를 활용하는 것이 선행연구의 일반적인 경향으로 확인된다. 이 연구는 2016년 이후에 출판된 지역 기반 인구집단을 대상으로 일관된 기준에 의거한 문헌조사 결과를 제시한다. PRISMA 지침에 따른 Web of Science 데이터베이스 검색을 통해 SCIE 및 SSCI에 등재된 저널에 출판된 논문 중 참가자 4,000명 이상의 지역 기반 코호트 연구 8편을 확인하였다. 8편의 논문에서 한파 노출은 치매 위험 증가와 연관되었으며, 65세 이상 고령층과 난방 인프라가 부족한 지역에서 결과가 가장 일관되게 나타났다. 검색전략을 SCIE/SSCI 등재 학술지로 한정하였기 때문에, 본 검토는 관련된 모든 임상적 또는 역학적 근거를 포괄하지 못했을 가능성이 있다. 그럼에도 불구하고, 지역 기반 인구집단에 의거하여 치매 위험을 평가한 본 연구는 향후 비교 연구 및 종단연구를 위한 중요한 참고자료가 될 것으로 기대된다.

Cold waves have emerged as an extreme weather phenomenon and a significant environmental factor triggering dementia in older adults. However, most existing research has centered on clinical cohorts of specific hospital patients, limiting objective analysis of regional differences in the impact of cold waves on dementia incidence. This study offers a structured review focused on region-wide population-based studies appearing in the literature since 2016. Following PRISMA guidelines, a Web of Science search yielded eight region-wide studies from SCIE and SSCI-indexed journals, each with sample sizes of 4,000 or more participants. Evidence from eight studies indicates that cold wave exposure is associated with elevated dementia risk, with the most consistent effects seen in older adults (aged ≥ 65 years) and in communities with inadequate heating infrastructure. Although restriction to SCIE and SSCI-indexed journals may limit full coverage, the findings from region-wide population studies provide a methodologically rigorous foundation for future comparative and longitudinal research.

목적: 20대 남녀를 대상으로 눈꼬리가 올라간 눈에 아이라이너를 적용하여 추출한 뇌파와 감성반응을 통하여 정량적 데이터 구축 을 하기 위함이다. 방법: 본 연구는 눈꼬리를 올려 변형한 눈에 5가지 아이라이너를 적용하여 자극물을 만들었다. 자극물을 통하여 20대 성인 남녀를 대상으로 뇌파(coefficient of variation for the brainwave, CVB)와 평균선호도지수(API)을 도출하여 형용사 이미 지 맵에 포지셔닝을 하였다. 그리고 호감도와 베타와의 상관관계를 분석하여 메이크업 이미지를 과학적으로 분석할 수 있는 방법을 제시하였다. 결과: 자극물을 통하여 추출한 뇌파와 감성평가 결과는 남녀 모두 θ파에서 NL의 자극에서 활성 되었고, α파도 비슷한 경향으로 AA자극에서 덜 감소되었다. β파와 γ파의 활성성비율은 PU의 자극에서 가장 높았다. 여성이 남성에 비하여 β파와 γ파의 활성정도가 컸으나 아이라이너 자극에 의한 뇌파반응 경향은 남녀가 비슷하였다. 눈꼬리가 올라간 눈에 대한 남녀의 감성은 여성적 이적이라고 공통적인 반응이었다. 호감도 지수는 남녀 모두 NL의 자극에서 좋았으며, AA의 평가도 좋았다. PU의 자극시 아이라이 너 호감도 지수는 남녀 모두 낮게 평가되었다. 5가지 아이라이너를 적용한 자극물 중 PU의 자극에서 양과 음의 이미지가 골고루 포 지셔닝 되었다. 결론: 눈꼬리가 올라간 눈에 적용된 아이라이너의 자극물을 보고 도출한 뇌파와 감성반응 결과는 남녀 간에 차이는 없었다. 본 연구 결과는 정성적 판단으로 시행하는 메이크업을 정량적인 이미지로 도출할 수 있는 가능성을 제시하였다. 향후 감성 반응과 뇌파값의 상관관계 데이터를 더 구축할 경우 뷰티 산업의 활용도가 높을 것으로 판단된다.

Purpose: To establish quantitative data through brain waves and emotional responses by applying eyeliners to sloe eyes in males and females in their twenties. Methods: This study created stimulants by applying five eyeliners to eyes whose shapes were changed by raising their tails. Using stimulants, the coefficient of variation for brainwaves and average preference indices were obtained from males and females in their twenties, and then were positioned on an adjective image map. It is also suggested how to scientifically analyze make-up images based on a correlation between preference and beta. Results: The evaluation of brain waves and emotions collected from stimulants showed that, for both males and females, a θ wave was activated using the NL stimulation, and α wave was less decreased using the AA stimulation. The activation rates of β and γ waves were most increased by PU stimulation. Although the activation of β and γ waves in males were higher than those in females, the brain wave response tendency stimulated by eyeliners was similar in individuals with both genders. The emotional responses to sloe eyes in individuals with both genders were commonly feminine. The preference indices in both males and females were high for the NL stimulation, and the valuation index of the AA simulation was also good. The preference indices of eyeliners in the males and females were low for the PU stimulation. Among the stimulants to which five eyeliners were applied, those of PU allowed regular the positioning of positive and negative images. Conclusion: There were no discrepancies in the brain waves and emotional responses of the males and females derived from stimulants of eyeliners applied to sloe eyes. The results suggest that it is possible to draw quantitative images from a make-up that is conducted based on a qualitative evaluation. If the data of correlations between emotional responses and brain waves are further collected, they would be efficiently used in the beauty industry.

目的: 通过在二十多岁的男性和女性的眼角上翘的眼上涂抹眼线，通过脑电波和情绪反应建立定量数据。方法: 将五种眼线膏涂在上翘的眼角上从而改变眼睛的形状来制造刺激物。利用刺激物，从二十多岁的男性和女性获 得脑电波的变异系数和平均偏好指数，然后将其置于形容词图像地图上。还建议了如何根据偏好和beta之间的 相关关系科学分析彩妆图像。结果: 通过刺激物收集的脑电波和情绪的评估表明，对于男性和女性，NL刺激均 激活了θ波，而AA刺激则降低了α波。通过PU刺激，β和γ波的激活率增加最多。尽管男性的β和γ波的激活程度 高于女性，但眼线刺激的脑电波响应趋势在男女中均相似。男性和女性对眼角上翘的眼睛的情感反应通常是女 性的。NL刺激下，男性和女性的偏好指数都很高，AA模拟的评估指数也很好。对于PU刺激，男性和女性眼线 的偏好指数均较低。在施加了五种眼线的刺激中，正负图像在PU刺激中均匀分布。结论: 眼线膏涂在上翘的眼 角上产生的刺激物引起的男女脑电波和情绪反应无差异。通过研究提出定性评估的彩妆中绘制定量图像的可行 性。如果进一步收集情绪反应和脑电波之间的相关性数据，它们将被有效地用于美容行业。

목적: 색상 적용방법인 대조와 유사색 배색방법을 아이 쉐도우 색상에 적용하여 배색에 따른 얼굴에 미치는 영향을 체계적으로 파 악하고자 한다. 방법: 20대 여성 30명을 대상으로 기본형의 아무런 색을 입히지 않은 눈(Non)에 아이 쉐도우를 대조와 유사색 배색 으로 각각 3 가지씩 제작하여 뇌파를 측정하였다. 측정된 뇌파는 뇌파변동계수(CVBs)와 모서리주파수(SEF50, 90)로 분석하였고, 8 개의 감성 형용사 쌍의 척도 값을 평균 선호도 지수(API)로 감성평가 하였다. 뇌파와 감성평가에 대한 통계분석은 SPSS를 사용하여 반복측정 분산분석(repeated measure analysis of variance)을 실시하였고, 95% 신뢰수준에서 Tukey's test를 통해 사후검증을 하 였다. 결과: 아이 쉐도우의 대조 배색은 유사색 배색보다 전반적으로 집중과 각성지표인 β파와 γ파가 활성 되었으며, 특히 B/W 배 색에서 가장 크게 증가하였다. 유사색 배색 자극 중 RP/B 배색에서 β파와 γ파의 활성 정도가 크게 나타났다. 대조 배색에서 hard, strong, heavy로 평가되었고, 유사색 배색에서는soft, dynamic, feminine, brilliant, bright한 공통적인 반응을 보였다. 아이 쉐도우 의 대조와 유사색 배색의 API는 β파와 반비례 관계였으며 API 반응이 양(+)으로 평가될수록 β파의 활성 정도가 작았다. API 반응결 과는 톤이나 색상 차이가 클 경우 negative로 평가되었고, 유사색 배색은 positive로 평가되었다. 결론: 아이 쉐도우의 배색 방법에 따른 뇌파와 감성반응 결과들은 아이 쉐도우 색상에 배색방법에 따라 얼굴에 미치는 영향을 정량적인 DB로 구축을 할 수 있는 기반 을 마련하였다. 이를 통해 효과적인 이미지 연출과 인터페이스 개선에 보조적 역할을 할 수 있을 것으로 사료된다

Purpose: This study aims to systematically examine the effects of color arrangement on faces using a color application method for eye shadow: the contrast and similar color arrangement. Methods: Three kinds of eye shadows were applied on 30 participants (women in their 20s) with no eye make-up eyes (Non), depending on the contrast and similar color arrangement, method respectively. The coefficient of variation for brain waves (CVBs) and corner frequencies (SEF50, 90) were analyzed by measuring their brain waves as well as the scale values of eight pairs of emotional adjectives by introducing the average preference index (API). Statistical analysis of EEG and emotional evaluation was performed using SPSS, followed by repeated measure analysis of variance and post-test with Tukey's test at 95% confidence level. Results: Both concentration and awareness index, β, and γ wave, of the contrast color arrangement of eye shadows were entirely more activated than the similar color arrangement with an especially, high increase for the black/ white color arrangement. The activity was also stronger for the red-purple/blue color arrangement, among the similar color arrangement stimulation. The contrast color arrangement was commonly evaluated as hard, strong, and heavy, while the similar color arrangement was also commonly evaluated as soft, dynamic, feminine, brilliant, and bright. As the contrast of eye shadow and API reaction of similar color scheme were evaluated as positive (+), the degree of activity of β wave was small. Conclusion: The results of brain waves and emotional responses, to the color arrangement of eye shadows supposedly played an assistive role in producing effective images and improved interfaces, to establish a foundation for the quantitative DB of effects of eye shadow color arrangement.

目的: 系统地研究将颜色匹配方法即颜色对比和相似方法应用于眼影颜色，了解颜色对脸部的影响。方法: 根据 对比度和类似的颜色排列方法，分别对20多岁女性30名没有眼部化妆眼（非）的参与者应用三种眼影。脑波利 用脑波变动系数（CVBs）和角频率（SEF50，90）分析，感性评价通过引入平均偏好指数（API）来测量八对 情绪形容词的比例值来分析。使用SPSS进行EEG和情绪评估的统计分析，然后使用Tukey's检验以95％置信水 平重复测量方差分析和后测试。结果: 眼影的对比色比相似颜色的对比色更活跃，β和γ波作为浓度和唤醒指数被 激活最多，特别是在B/W着色中。RP/B中β-和γ-波的活动，在对比色中，它被评价为坚硬，坚固，重。在类似 的配色方案中，柔软，动感，女性化，灿烂，明亮表现出共同的反应。眼影和相似性着色API的对比度与β波成 反比，并且当API反应被评估为阳性（+）时，β波的活性较小。当色调或色差大时，API反应的结果被评价为阴 性，并且相似的颜色被评价为阳性。结论: 根据眼影着色方法的脑电图和情绪反应的结果为根据着色方法构建关 于眼影颜色对脸部的影响的定量DB提供了基础。因此，它可以起到有效图像渲染和界面改进的辅助作用。

Electroencephalogram (EEG) research has gained widespread use in various research domains due to its valuable insights into human body movements. In this study, we investigated the optimization of motion discrimination prediction by employing an artificial intelligence deep learning recurrent neural network (gated recurrent unit, GRU) on unique EEG data generated from specific movement types among EEG signals. The experiment involved participants categorized into five difficulty lev-els of postural control, targeting gymnasts in their twenties and college students majoring in physical education (n=10). Machine learning tech-niques were applied to extract brain-motor patterns from the collected EEG data, which consisted of 32 channels. The EEG data underwent spectrum analysis using fast Fourier transform conversion, and the GRU model network was utilized for machine learning on each EEG frequen-cy domain, thereby improving the performance index of the learning operation process. Through the development of the GRU network algo-rithm, the performance index achieved up to a 15.92% improvement com-pared to the accuracy of existing models, resulting in motion recognition accuracy ranging from a minimum of 94.67% to a maximum of 99.15% between actual and predicted values. These optimization outcomes are attributed to the enhanced accuracy and cost function of the GRU net-work algorithm’s hidden layers. By implementing motion identification optimization based on artificial intelligence machine learning results from EEG signals, this study contributes to the emerging field of exercise re-habilitation, presenting an innovative paradigm that reveals the inter-connectedness between the brain and the science of exercise.

This study proposes a methodology to interpret cylindrically propagating elastic waves as analogous to waves propagating in Cartesian coordinates. By employing coordinate transfor-mations and leveraging the symmetry of wave propagation, the approach simplifies the complexi-ties inherent in cylindrical coordinate systems. This framework enables the application of existing Cartesian-based analytical techniques to cylindrical wave problems, providing enhanced computa-tional efficiency. The proposed method holds potential for various engineering applications, includ-ing elastic wave-based nondestructive testing and structural optimization, particularly in complex media and structures.

This study proposes a methodology to interpret cylindrically propagating elastic waves as analogous to waves propagating in Cartesian coordinates. By employing coordinate transformations and leveraging the symmetry of wave propagation, the approach simplifies the complexities inherent in cylindrical coordinate systems. This framework enables the application of existing Cartesian-based analytical techniques to cylindrical wave problems, providing enhanced computational efficiency. The proposed method holds potential for various engineering applications, including elastic wave-based nondestructive testing and structural optimization, particularly in complex media and structures.

본 연구에서는 도시 폭염의 현황과 정책적 요인을 분석하고, 이를 통한 동태적 관계를 분석하고자 한다. 즉 폭염에 영향을 미치는 직⋅간접적 요인들을 파악하여 통합적인 인과관계를 구축하고자 한 다. 연구의 목적 달성을 위하여 도시 폭염의 추세와 경제⋅사회⋅환경에 미치는 피해를 분석하였으 며 선행연구를 통해 각 요인간의 관계를 고찰하였다. 이를 통해 다음과 같은 결과가 도출되었다. 첫째, 우리나라의 도시의 온도 증가는 불투수면적 증가에 의해 진행되는 단순한 의미의 도시화가 아니라 지역의 경제⋅사회⋅환경 역량 차원에서 빠른 대응이 필요하다는 점이다. 우리나라 도시의 온도 증가를 보다 정확하게 예측하고 설득력 있는 정책방안을 제안하기 위해서는 도시 폭염 과정과 도시 안전성이 매우 비선형적⋅동태적으로 초래된다는 새로운 접근시각이 필요하다. 셋째, 도시라는 한정된 공간에서 폭염을 유발하는 다양한 요인들 간의 인과관계를 검토하고 도시의 사회경제적 여건 을 안전하게 유지할지에 대한 도시 안전 서비스 수준개선 방안을 모색해 보아야만 한다는 것이다.

In this study, we analyzed the potential determinants of urban heat waves in Korea and their dynamic relationship using a system dynamics analysis approach. We developed an integrated causal loop diagram and identified the direct and indirect factors influencing urban heat waves. The followings are the main findings of this study. First, the rise of temperature in Korea is not simply due to the increase of impervious areas affected by urbanization but should be seriously recognized as a critical issue of heat waves which may lead to the annihilation of the areas. Second, for more accurate prediction of the temperature increase and development of effective policy responses, we need a new approach that focuses on a non-linear and dynamic relationship between urban heat wave process and urban safety. Third, it is critical to explore policy measures for maintaining socioeconomic conditions and improving the level of urban safety based on the multi-dimensional examination of causal relationships across various determinants for urban heat waves in South Korea.

The Seismic waves is if it is not the only, the one of the most important part to understand inner structure of the earth because we can see the structure of inner earth by detecting the changes of velocity of seismic waves. So, many people deal with seismic waves importantly, but it is too hard to understand knowledge visually about seismic waves in the textbook and reference books associated with seismic waves. Especially, many students just memorize a fact that the seismic shadow zone is a place which both p and s wave can’t reach but they don’t understand it perfectly. So, making the device, that can detect sound waves substitute to seismic waves, leads to more deep understanding about seismic waves. Then, shock the sound wave, or seismic wave, to the device and detect it by a small microphone so, detect the seismic shadow zone by analyzing sound waves.

This paper examines bank merger waves in Japan and their effect on competition in the Japanese commercial banking market for the period of 1983-2006. The H-statistic of the Panzar-Rosse model is estimated separately for three different time periods, the boom, the bubble burst and the recovery. This paper concludes that the bank mergers that took place in Japan have not led to a higher level of market power except for the period of financial crisis brought by the bubble burst. Recent mergers in the Japanese banking sector do not seem to harm the competition level in the banking market. Contrary to the decreasing trend of Chinese banks’ overall market concentration, the Japanese and Korean banking industries share commonality in their merger activities and market concentration trend, that is, an increase in bank mergers, creation of mega banks and an increase in overall market concentration. Even with a decrease in market concentration, the Chinese banking industry is still highly concentrated and its level of competition is close to oligopoly, whereas both the Japanese and Korean banking industries have a market structure of monopolistic competition. The city banks in Japan tend to be more competitive than its Korean counterpart while the Korean regional banks are more competitive than its Japanese counterpart.