• Journal of Biomedical Engineering Research
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• v.16 no.4
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• pp.507-516
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• 1995

The nonstationary identifier in the DCT domain is suggested in this study for the identification of AR parameters of above-lesion upper-trunk electromyographic (EMG) signals as a means of developing a reliable real time signal to control functional electrical stimulation (FES) in paraplegics to enable primitive walking. As paraplegic shifts his posture from one attitude to another, there is transition period where the signal is clearly nonstationary. Also as muscle fatigues, nonstationarities become more prevalent even during stable postures. So, it requires a develpment of time varying nonstationary EMG signal identifier. In this paper, time varying nonstationary EMG signals are transformed into DCT domain and the transformed EMG signals are modeled and analyzed in the transform domain. In the DCT domain, we verified reduction of condition number and increment of the smallest eigenvalue of input correlation matrix that influences numerical properties and mean square error were compared with SLS algorithm, and the proposed algorithm is implemented using IMS T-805 parallel processing computer for real time application.

• Management & Information Systems Review
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• v.38 no.4
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• pp.41-60
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• 2019

The purpose of this study is to investigate the effect of salesperson's adaptive selling tactics on consumers who purchase Small and Medium Enterprises' product with the help of salespeople in the store. Specifically, we examine whether salesperson's adaptive selling tactics affect consumers hedonic shopping value and utilitarian shopping value. Furthermore, we try to figure out the effect of shopping value on the salesperson relationship commitment and consumer product satisfaction. The subjects of this study have surveyed the consumers with experience in purchasing SME's products through salespeople in the Gyeongnam area. As data process, SPSS 21.0 was used as the analysis tool and AMOS 21.0 was used to analyze the structural equation model. The implications of these findings are as follows. First, the salesperson's role has a positive effect on the consumer's product satisfaction. Second, it can be suggested that the salesperson's adaptive selling tactics are an important variable affecting the consumer's shopping value. Third, the results on the consumers who have hedonic shopping value have a strong positive influence rather than the consumers who have the utilitarian shopping value. The adaptive selling tactics of the salesperson should be encouraged to increase sales performance. In order to generate more performance in a competitive market environment, it is necessary to continuously strive to increase contact between the salesperson and the consumer in order to improve the quality of the relationship.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.209-217
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• 2010

Recently, some mathematical models for the prediction on progress of carbonation of concrete were reported. These models take account for $CO_2$ diffusion and chemical reaction between $Ca(OH)_2$ and $CO_2$. Based on the assumption that $CO_2$ diffuses in the carbonation zone and reacts with $Ca(OH)_2$ at the outer face of carbonation zone and non-carbonation zone. In this study, a mathematical model to predict the progress of carbonation of concrete has been established based on the reducing concentration of $Ca(OH)_2$ in the carbonation progress zone, where $Ca(OH)_2$ reacts with $CO_2$ and $Ca(OH)_2$ and $CaCO_3$ coexist. Also, the prediction model of carbonation progress rate of concrete using the air permeability coefficient regarding to $CO_2$ diffusion is developed. As a result of this study, an expression, the model equation is obtained for the prediction of carbonation based on the time and interaction velocity between $CO_2$ and Ca(OH)$_2$ dependent air permeability coefficient. The prediction by the model satisfied the experimental data of the accelerated carbonation for painted concrete. Consequently, the model can predict the rate of carbonation and the potential service life of concrete structure exposed to atmosphere.

• The Korean Journal of Financial Management
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• v.22 no.1
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• pp.1-36
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• 2005

In this study, we analyzed determinant factors of leverage ratio and debt maturity for Korean firms in the simultaneous equation system using 2SLS (two stage least square) method under assumption that two variables are jointly determined in the capital structure decision. As a result of the analysis, we found that leverage ratio and debt maturity are positively related. Also, as for determinant factors of debt maturity, agency cost hypothesis, asset maturity matching hypothesis, signalling and liquidity risk hypothesis are all generally supported, and further leverage ratio are significantly positively related with firm size, but negatively related with default risk. However, when we divided samples into groups according to bank debt level and Chaebul affiliation, with contrast to existing study which worked on similar issues with OLS, we found no evidence supporting the argument that the information asymmetry problem is less severe in firms with more bank debt, whereas information asymmetry and financial constraint problems are more severe in non-Chaebul affiliated firms.

• Geophysics and Geophysical Exploration
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• v.13 no.4
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• pp.315-322
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• 2010

The phase-screen and the split-step Fourier migrations, which are implemented in both the frequency-wavenumber and frequency-space domains by using one-way scalar wave equation, allow imaging in laterally heterogeneous media with less computing time and efficiency. The generalized-screen migration employs the series expansion of the exponential, unlike the phase-screen and the split-step Fourier migrations which assume the vertical propagation in frequency-wavenumber domain. In addition, since the generalized-screen migration generalizes the series expansion of the vertical slowness, it can utilize higher-order terms of that series expansion. As a result, the generalized-screen migration has higher accuracy in computing the propagation with wide angles than the phase-screen and split-step Fourier migrations for media with large and rapid lateral velocity variations. In this study, we developed a 2D prestack generalized-screen migration module for imaging a complex subsurface efficiently, which includes various dips and large lateral variations. We compared the generalized-screen propagator with the phase-screen propagator for a constant perturbation model and the SEG/EAGE salt dome model. The generalized-screen propagator was more accurate than the phase-screen propagator in computing the propagation with wide angles. Furthermore, the more the higher-order terms were added for the generalized-screen propagator, the more the accuracy was increased. Finally, we compared the results of the generalizedscreen migration with those of the phase-screen migration for a model which included various dips and large lateral velocity variations and the synthetic data of the SEG/EAGE salt dome model. In the generalized-screen migration section, reflectors were positioned more accurately than in the phase-screen migration section.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.2
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• pp.23-33
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• 2011

In this study, a CFPBS (Cone-type Friction Pendulum Bearing System) was developed which controls the acceleration delivered to the structure to prevent damage and degradation of the critical communication equipment in case of an earthquake. The isolation performance of the CFPBS was evaluated by numerical analysis. The CFPBS was manufactured in the shape of a cone differenced from the existing FPS (Friction Pendulum System), and a pattern was engraved on the friction surface. The natural frequencies of the CFPBS were evaluated from a free-vibration test with the seismic isolator system consisting of four CFPBSs. In order to verify its earthquake-resistant performance, a numerical analysis program was created from the equation of the CFPBS induced from the equations of motion. A simplified theoretical equation of the CFPBS was proposed to manufacture the equipment which could demonstrate the necessary performance. Artificial seismic waves satisfying the maximum earthquake scale of the Korean Building Code-Structural (KBC-2005) were created and verified to review the earthquake-resistant performance of the CFPBS by numerical analysis. The superstructural mass of the CFPBS and skew angle of the friction surface were considered for numerical analysis with El Centro NS (1940), Kobe NS (1995) and artificial seismic waves. The CFPBS isolation performance evaluation was based on the results of numerical analysis and the executed comparative analysis between the results from numerical analysis and the simplified theoretical equation under the same conditions.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.521-521
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• 2012

우리나라는 산악지역이 국토의 대부분을 차지하고 있어 전체유역을 놓고 볼 때 대하천이 차지하는 부분보다는 중소하천이 차지하는 부분이 상대적으로 크고, 교량의 길이가 짧은 소교량이 수적으로 많은 부분을 차지하고 있다. 그중에서도 특히 중소하천의 유량은 시간적으로 매우 빠르게 변화하며 유속 또한 급속히 빨라져 하상의 변형이 순식간에 일어나고 있다. 이와 같은 시간적, 공간적인 호우특성과 지형특성으로 인하여 중소하천에 위치한 교량은 특히 세굴에 매우 취약함을 보여주고 있다. 하천에 건설되는 교량의 수명이나 안정성에 세굴이 미치는 영향은 매우 크며, 특히 우리나라와 같이 홍수 시 단기간에 걸쳐 유량이 급증하는 경우 유속에 의한 교량 기초의 급격한 세굴은 예상치 못한 교량 붕괴 사고를 초래할 수 있다. 현재 국내 소하천에 설치된 교량은 약 3,470개소(지방도 기준)로 다양한 하부구조로 설계되어 있다. 이렇게 하천 내에 세워진 교량과 같은 횡단 구조물들은 그 크기에 상관없이 하천의 형태에 영향을 미치게 된다. 그중에서 교량 세굴은 하천 횡단구조물로 인하여 발생되는 가장 중요한 문제 중의 하나로써 교량 건설 시 교각에 영향을 주는 세굴을 예측하고 방어하기 위하여 다양한 방정식을 통하여 신설교량의 교각세굴을 예측한다. 하지만 대부분의 교량 세굴 공식들은 실험실에서의 실험 결과를 토대로 개발되었기 때문에 이들 공식들이 산정한 국소 세굴량이 얼마나 정확한지는 실제 현장 관측 자료와의 비교를 통해서만 검증할 수 있다. 세굴 공식들의 산정 결과를 현장 실측자료와 비교하는 연구는 그 동안 다양하게 시도되었으나, 통일된 결론에는 도달하지 못하고 있다. 본 연구에서는 기존의 세굴깊이 산정 시 일반적으로 사용되어지고 있는 세굴공식들 중 소하천 교량 규모에 적용 가능한 공식들을 선별하고, 각 세굴심 추정공식에 속한 변수별 특성분석을 위하여, 5가지의 독립변수를 설정하여 국부세굴의 현장 측정값과 예측공식의 비교결과에 대하여 불일치율을 비교분석하였다. 그 결과, 모든 공식들의 불일치율의 기하 평균이 1보다 큰 것을 보여주고 있다. 즉, 모든 공식들이 과대 추정의 의미로 정확성면에서 우수한 공식들은 불일치율의 기하 평균이 1에 가깝고 기하 표준편차가 작은 공식들이 나타났으며, 이런 점에서 Froehlich 공식, Inglis-Poona II, Blench-Inglis I, Breusers 공식 등의 기하평균이 1에 가장 근접한 결과를 나타내었다. 각 세굴공식 세굴심 산정결과의 불일치율을 각각 5가지의 변수별로 도시하여 분석하였으며, 그 결과로 소하천에 대하여 적용 가능한 공식과 소하천에 적용 시에는 과다추정의 우려가 있는 공식으로 분류되어 면밀한 검토가 필요할 것으로 판단된다.

• Radiation Oncology Journal
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• v.7 no.2
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• pp.171-183
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• 1989

A general effect for cell proliferation has been incorporated into Roesch's survival equation (Accumulation Model). From this an isoeffect formula for the low dose-rate regimen is obtained. The prediction for total doses equivalent to 60Gy delivered at the constant dose-rate over 7 days agrees well with the dose-time data of Paterson and of Green, when the parameter ratio A/B (${\approx}{\alpha{\mu}}/2{\beta}\;where\;{\mu}$ is the repair rate) is chosen to be 0.7Gy/h. When a constant proliferation rate and known facts of division delay are assumed, an isoeffect relation between low dose-rate treatment and acute dose-rate treatment can be derived. This formula in the regimens where proliferation is negligible predicts exactly the data of Ellis that 8 fractions of 5 Gy/day for 7 days are equivalent to continuously applied 60Gy over 7days, provided the A/B ratio is 0.7 Gy/h and the $\alpha/\beta$ ratio is 4Gy. Overall agreement between the clinical data and the predictions made by the formula at the above parameter values suggests that the biologcal end points used as the tolerance level in the studies by Paterson, Green, and Ellis all agree and they are not entirely the early effects as generally assumed. The absence of dose-rate effects observed in the mouse KHT sarcoma can better be explained in terms of a large value for the A/B ratio. Similarly, the same total dose used independently of the dose-rate to treat head and neck tumors by Pierquin can be justified.

• Journal of Korea Water Resources Association
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• v.52 no.10
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• pp.697-706
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• 2019

A multiphase flow modeling approach equipped with a hybrid turbulence modeling method is applied to compute the gravity currents in a rectangular channel. The present multiphase solver considers the dense fluid, the less-dense ambient fluid and the air above free surface as three phases with separate flow equations for each phase. The turbulent effect is simulated by the IDDES (improved delayed detach eddy simulation), a hybrid RANS/LES, approach which resolves the turbulent flow away from the wall in the LES mode and models the near wall flow in RANS mode on moderately fine computational meshes. The numerical results show that the present model can successfully reproduce the gravity currents in terms of the propagation speed of the current heads and the emergence of large-scale Kelvin-Helmholtz type interfacial billows and their three dimensional break down into smaller turbulent structures, even on the relatively coarse mesh for wall-modeled RANS computation with low-Reynolds number turbulence model. The present solutions reveal that the modeling approach can capture the large-scale three dimensional behaviors of gravity current head accompanied by the lobe-and-cleft instability at affordable computational resources, which is comparable to the LES results obtained on much fine meshes. It demonstrates that the multiphase modeling method using the hybrid turbulence model can be a promising engineering solver for predicting the physical behaviors of gravity currents in natural environmental configurations.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.228-238
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• 2019

The purpose of this study is to investigate the relationship between transaction justice and customer performance. In this study, data were gathered from questionnaires from customers and suppliers of manufacturing outsourcing service, and reliability, validity, and confirmatory factor analysis (CFA) were conducted and the hypothesis was verified through the structural equation modeling (SEM) analysis. The results of this study are as follows: 1)Transaction justice has a significant positive effect on customer's business performance. Distribution and Interactional justice have a small effect on business performance, but Procedural justice has a significant positive effect. 2)Transaction justice has a positive effect on partnerships. 3)The partnership between the customer and the supplier has a positive effect on the customer's business performance. 4)Partnership has positive effect on customer's management performance through mediating justice. This study is based on the fact that justice acts as a independent variable in the transactional relationship between the customer and the supplier in the manufacturing outsourcing and this is the first case that empirically investigated the effect of the justice on the customer's management performance. In order to effectively cope with a rapidly changing business environment and effectively improve management performance, it is necessary to make efforts to improve justice, especially procedural justice, by utilizing outsourcing effectively in a global competition. In this respect, this study provides important implications for the both academically and practically.