• 한국전기전자재료학회논문지
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• 제23권2호
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• pp.137-142
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• 2010

A plane wave expansion method (PWEM) was applied for photonic band structure calculation. We examined zero group velocity modes in photonic crystal. The zero group velocity modes were obtained at the second band along F-K direction. We expanded higher order Brillouin zone (BZ) to find the locations of zero group velocity modes and to investicate their properties. We found twelve locations, inside the first Brillouin zone, where the group velocities became zero. Also, we calculated band structure and group velocity in off-plane configuration.

• Nuclear Engineering and Technology
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• 제34권1호
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• pp.90-103
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• 2002

The thermal and mechanical properties of compacted bentonite and bentonite-sand mixture were collected from the literatures and compiled. The thermal conductivity of bentonite is found to increase almost linearly with increasing dry density and water content of the bentonite. The specific heat can also be expressed as a function of water ontent, and the coefficient of thermal expansion is almost independent on the dry density. The logarithm of unconfined compressive strength and Young’s modulus of elasticity increase linearly with increasing dry density, and in the case of constant dry density, it can be fitted to a second order polynomial of water content. Also the unconfined compressive strength and Young’s modulus of elasticity of the bentonite-sand mixture decreases with increasing sand content. The Poisson’s ratio remains constant at the dry density higher than 1.6 Mg/m$_3$, and the shear strength increases with increasing dry density.

• International Journal of Internet, Broadcasting and Communication
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• 제11권1호
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• pp.39-46
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• 2019

This paper proposes an adaptive threshold watershed algorithm, which is the method used for image segmentation and boundary detection, which extends the region on the basis of regional minimum point. First, apply adaptive thresholds to determine regional minimum points. Second, it extends the region by applying adaptive thresholds based on determined regional minimum points. Traditional watershed algorithms create over-segmentation, resulting in the disadvantages of breaking boundaries between regions. These segmentation results mainly from the boundary of the object, creating an inaccurate region. To solve these problems, this paper applies an improved watershed algorithm applied with adaptive threshold in regional minimum point search and region expansion in order to reduce over-segmentation and breaking the boundary of region. This resulted in over-segmentation suppression and the result of having the boundary of precisely divided regions. The experimental results show that the proposed algorithm can apply adaptive thresholds to reduce the number of segmented regions and see that the segmented boundary parts are correct.

• 식품과학과 산업
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• 제49권2호
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• pp.56-62
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• 2016

Although the production of chestnut in Korea is the second largest in the world, domestic consumption of chestnut is very limited. Furthermore, consumption of chestnut in Korea is highly dependent on export to Japan and China. Large amount of chestnut in Korea have been deteriorated and discarded during storage. In order to increase the consumption of chestnut in Korea, it is necessary to know the processing properties of chestnut and its starch. Additionally, through the various investigations such as modification treatment, it will be extended to utilization of chestnut. So far, there is a little information on the processing properties of chestnut; therefore, the expansion of research will bring results to increase the consumption of chestnut.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제27권3호
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• pp.180-193
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• 2023

Approximating the implied volatilities and estimating the model parameters are important topics in quantitative finance. This study proposes an approximation formula for short-maturity near-the-money implied volatilities in stochastic volatility models. A general second-order nonlinear PDE for implied volatility is derived in terms of time-to-maturity and log-moneyness from the Feyman-Kac formula. Using regularity conditions and the Taylor expansion, an approximation formula for implied volatility is obtained for short-maturity nearthe-money call options in two stochastic volatility models: Heston model and SABR model. In addition, we proposed a novel numerical method to estimate model parameters. This method reduces the number of model parameters that should be estimated. Generating sample data on log-moneyness, time-to-maturity, and implied volatility, we estimate the model parameters fitting the sample data in the above two models. Our method provides parameter estimates that are close to true values.

• International journal of advanced smart convergence
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• 제13권2호
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• pp.94-102
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• 2024

This study examines the factors influencing loyalty to cultural arts events using data from the Survey Report on National Culture and Arts Activity in 2022 and 2023. The dependent variable is a binary variable representing the intention to revisit in the future, which serves as a proxy for loyalty. Given that the dependent variable is binary, the logit model specification is employed to estimate the average marginal effects. The estimation results indicate that audience satisfaction exerts the strongest influence on loyalty in both years. It can be observed that participation in cultural arts events is the second most important variable in determining loyalty. This suggests that the government should support the expansion of the scope of these activities and the diversification of programs in order to facilitate greater participation in a wider range of cultural arts activities.

• 한국가정과학회지
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• 제7권3호
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• pp.15-33
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• 2004

A precise understanding of the human form in static pose serves as the basis of designing clothing. When the human body is in motion, however, even an article of clothing designed to fit the human form in static pose can pull and change, thus restricting the body. In order to increase the fit of the clothing, which may be termed the second skin, its form and measurements therefore must be determined in correlation not only with the formal characteristics of the human body, in static pose but also with its functional characteristics in motion, as caused by the movements of the human body. In this study, the motion factor was selected as the primary basis for designing slacks with good fit in both static and moving states. By indentifying the areas in which lower limb movement cause significant changes in body surface lines, we suggest several application methods for designing slacks. Using unmarried female university students aged 18 - 24 as subjects, a total of 32 body surface categories (15 body surface lines and 17 body surface segment lines) were measured in one static and 9 movement poses. In particular, expansion and contraction levels and rates were measured and used in the analysis. The analysis first involved the calculation of the average measurement per body part in body surface line in static pose as well as of the average expansion and contraction levels and rates in 9 lower limb movements. Two-way MANOVA and multiple comparison analysis (Tukey) were conducted on movements and individual somatotypes regarding measurement per body part and expansion and contraction rates. Body parts whose measurements of body surface lines differed significantly in body surface line in static pose versus in movement were then identified. The results of this study are as follows. First, changes in body surface lines caused by lower limb movements were significant in all body surface lines of the lower trunk, both horizontal and vertical, with the exception of abdomen girth, midway thigh girth, ankle girth, hip length, and posterior knee girth. Second, significantly expanded 10 body surface lines in moving pose were detected and illustrated in table 4. These body parts should be studied in designing or pattern designing, especially for close-fitting pants, in using stretch fabric, and in sensory evaluation of good fit during movement.

• 직업교육연구
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• 제37권5호
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• pp.1-23
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• 2018

이 연구의 목적은 마이스터고의 교육 경쟁력을 강화하기 위한 학제 개편 방향을 탐색해 보는 것이다. 구체적으로는 첫째, 중등단계 직업교육의 학제 개편과 관련한 기존의 논의를 검토하여 마이스터고의 교육 경쟁력 강화에 초점을 맞춘 학제 개편안을 제시하고, 둘째, 이에 대한 관계자 인식 분석을 실시하여 마이스터고 학제 개편 방향 설정과 관련한 주요 시사점을 도출하고자 하였다. 이를 위해 먼저 중등단계 직업교육 학제 개편 관련 선행연구 분석을 토대로 (1) 학점제 도입, (2) 3학기제 도입, (3) 수업 연한 확대를 기본 틀로 하는 마이스터고 학제 개편안을 마련하였다. 다음으로 이러한 마이스터고 학제 개편안에 대한 관계자 인식 분석을 위해 마이스터고 교원 138명 및 마이스터고졸 취업자 185명을 설문조사를 실시하였다. 또한 산업체 현장의 의견 수렴을 위해 마이스터고에 대한 이해도가 높은 산업체 인사 4명을 선정하여 FGI를 실시하였다. 조사 내용은 '학제 개편의 필요성', '학제 개편안에 대한 인식', '학제 개편안 적용에 따른 기대효과' 등으로 구성하였으며, 설문조사 분석 결과 제시를 위해 빈도, 백분율, 평균 및 표준편차 등의 기초통계 분석을 실시하였다. 분석 결과, 첫째, 마이스터고 교원 및 마이스터고졸 취업자 모두 마이스터고 학제 개편의 필요성에 대해 동의한다는 응답이 비중이 더 높은 것으로 나타났다. 둘째, 제시된 마이스터고 학제 개편안의 도입 필요성에 대해 전반적으로 일정 수준 이상 필요한 것으로 나타난 반면, 적용 가능성에 대해서는 도입 필요성에 비해 전반적으로 다소 낮게 인식하고 있는 것으로 나타났다. 셋째, 산업체 인사들의 경우, 특히 수업 연한 확대에 따른 전공심화과정의 운영에 대해 긍정적인 반응을 보였다. 이러한 분석 결과를 토대로 '보다 체계적인 학제 개편 운영 모형 설계 및 이에 따른 정책적 지원 방안 마련', '추후 학제 개편안 적용 시, 시범 적용을 통한 전면적 확대 검토', '학제 개편안에 대한 산업현장 전문가 대상 체계적인 의견 수렴' 등을 제언하였다.

• 대한기계학회논문집B
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• 제26권5호
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• pp.666-674
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• 2002

A rapid expansion of the moist air or stream through transonic nozzle often leads to not-equilibrium condensation shock, causing a considerable amount of energy loss to the entire flow field. Depending on amount of heat released, condensation shock wave occurs in the nozzle and interacts with the boundary layer flow. In the current study, a passive control technique using a porous wall with a plenum cavity underneath is applied for purpose of alleviation the condensation shock wave in a transonic nozzle. A droplet growth equation is incorporated into two-dimensional wavier-Stokes equation systems. Computations are carried out using a third-order MUSCL type TVD finite-difference scheme with a second-order fractional time step. An experiment using an indraft transonic wind tunnel is made to validate the present computational results. The results obtained show that the magnitude of condensation shock wave is reduced by the current passive control method.

• 대한기계학회논문집B
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• 제26권7호
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• pp.951-958
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• 2002

Rapid expansion of a moist air or a stream through a supersonic nozzle often leads to non-equilibrium condensation shock wave, causing a considerable energy loss in flow field. Depending on amount of latent heat released due to non-equilibrium condensation, the flow is highly unstable or a periodical oscillation accompanying the condensation shock wave in the nozzle. The unsteadiness of the condensation shock wave is always associated with several kinds of instabilities as well as noise and vibration of flow devices. In the current study, a passive control technique using a porous wall with a plenum cavity underneath is applied for the purpose of alleviation of the condensation shock oscillations in a transonic nozzle. A droplet growth equation is coupled with two-dimensional Navier-Stokes equation system. Computations are carried out using a third-order MUSCL type TVD finite-difference scheme with a second-order fractional time step. An experiment using an indraft wind tunnel is made to validate the present computational results. The results show that the oscillations of the condensation shock wave are completely suppressed by the current passive control method.