• Toxicological Research
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• 제12권1호
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• pp.93-99
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• 1996

The effect of KTC-1, a new semisynthetic rifamycin antituberculous drug, on general toxicity, reproductive capability and fetal development was investigated in Sprague-Dawley rats. Male rats were administered KTC-1 with mashed feed from 63 days before mating to the end of mating period, and female rats were given from 14 days before mating to day 7 of gestation at dose levels of 0, 375, 750, and 1,500 ppm. The females were sacrificed on day 21 of gestation for examination of their fetuses. At 1,500 ppm, a reduction in body weight gain and testis atrophy were observed in male rats. Histological examination revealed testicular atrophy, absence or decrease of germinal cells, and vacuolization of Sertoli cells in testis. A reduction in body weight gain, a decrease in food consumption were found in female rats. In addition, decreases in the number of corpora lutea, iraplantations, and the litter size of live fetuses were seen. Mating, fertility, and pregnancy performances were also affected. There were no external abnormalities observed by examination of fetuses. At 750 ppm, a reduction in the body weight gain of male and female rats and decreases in the number of implantations and litter size were found. At 375 ppm, no treatment-related effects were observed. The results suggest that the no-effect dose levels (NOELs) of KTC-1 are 375 ppm for males and females on general toxicity, 750 ppm for males and females on reproductive capability, and 375 ppm for fetuses on embryonic development.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2004년도 추계 학술발표회 제16권2호
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• pp.49-52
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• 2004

In this studies, Dapped End Beams(DEB) having disturbed regions were designed by using strut tie model, and the main purpose of this paper is that whether T-headed bars and Steel fibers will be present or not. The ability of DEB with T-headed bars have a superior performance rather than others, such as improved ductility, larger energy adsorption and enhanced post-peak load carrying capability. The capacity of DEB with steel fibers also show increase of ductility, shear strength, fatigue strength and crack. Each DEB with both headed bars and steel fibers, headed bars, and steel fibers as a substitute reinforced steel in the disturbed regions and a DEB with only stirrup and tie reinforced steel were comparable. In contrast, the headed bar stirrups, the tie headed bars and the reinforced steel fibers did not lose their anchorage and hence were able to develop strain hardening and also served to delay buckling of the flexural compression steel. Excellent load-deflection predictions were obtained by increasing the tension stiffening effect to account for high load effects.

• 무역학회지
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• 제47권5호
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• pp.253-272
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• 2022

As the digital era accelerates, traditional perspectives have limitations in explaining the success or failure of export performance. The purpose of this study is to analyze new factors affecting export performance from the perspective of customer experience, which has emerged as an important factor in securing a competitive advantage and generating organizational performance. After deriving hypotheses based on literature review and discussion, a research model is designed in which three factors of customer experience such as understanding customer's objectives, customer value creation capability, and customer journey management are the antecedents, and export performance is the dependent variable. This model also includes organizational agility and personal contact as the moderating variables. To verify the hypotheses, multiple regression analysis was conducted on the collected data drawn from 198 SME exporters. According to the analysis results, it was found that all three antecedents positively affected export performance. In particular, the organizational agility and personal contact were confirmed to have a moderating effect that creates better export performance by interacting with customer value creation capability. The theoretical significance of this study is to find that effective customer experience management can be a key factor in creating export performance. The results suggest that checking the overall customer journey, exporters should select and intervene to intensively manage key touch points that can have a decisive impact on the quality of customer experience. At the end of the paper, practical implications to be considered in creating export performance through effective customer experience management are presented.

• 한국시뮬레이션학회논문지
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• 제30권1호
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• pp.87-101
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• 2021

무기체계의 성능을 뜻하는 작전운용성능(Required Operational Capability)은 신규 무기체계의 소요 결정 시 함께 결정되며, 무기체계의 획득부터 전술적인 운용에 이르기까지 결정적인 영향을 미치기 때문에 이를 정의하는 것은 매우 중요한 일이다. 본 연구에서는 새롭게 개발되는 무기체계인 관측포탄의 ROC를 검증하기 위한 시뮬레이션 기반의 방법론을 제안한다. 이를 위해, ROC를 구성하는 무기체계의 주요 성능과 무기체계의 성능에 영향을 미치는 외부환경요인을 입력값으로 하고, 작전운용효과를 결과값으로 출력하는 이산사건 시뮬레이션 모델을 제안한다. 시뮬레이션 모델을 구현하는데 필요한 모의논리를 설명하고 민감도 분석 등 다양한 시뮬레이션 결과를 활용하여 ROC를 검증할 수 있는 방법에 대해 설명한다. 본 연구는 관측포탄과 같이 유사무기체계가 없고 군의 분석모델을 직접적으로 활용하기 어려운 무기체계의 ROC를 분석하고 작전효과를 예측할 수 있는 방법론으로 활용이 가능할 것이다.

• 대한임베디드공학회논문지
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• 제9권3호
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• pp.173-182
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• 2014

The CRT monitor display system for SONAR signal that are commonly used in ships or naval vessels uses vector scanning method. Therefore the processing circuits of the system are complex. Also the purchase of parts is difficult as well as high-cost because the production had been shut down. FPGA-based embedded system is flexible to various digital applications because it can be able to simplify processing circuits and to make a easy customized design for end user, and it provides low-cost high-speed performance. In this paper, we describe an implementation of FPGA embedded system for real-time SONAR signal display using the triple buffering method to overcome some weakness of existing CRT system. Our system provides real-time acquisition and display capability of SONAR signal, and removes afterimage effect that is a critical problem of the system proposed in the preceding study.

• Structural Engineering and Mechanics
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• 제66권5호
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• pp.557-568
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• 2018

An investigation is made in the present work on the post-buckling and geometrically nonlinear behaviors of moderately thick perfect and imperfect rectangular plates made-up of functionally graded materials. Spectral collocation approach based on Legendre basis functions is developed to analyze the functionally graded plates while they are subjected to end-shortening strain. The material properties in this study are varied through the thickness according to the simple power law distribution. The fundamental equations for moderately thick rectangular plates are derived using first order shear deformation plate theory and taking into account both geometric nonlinearity and initial geometric imperfections. In the current study, the domain of interest is discretized with Legendre-Gauss-Lobatto nodes. The equilibrium equations will be obtained by discretizing the Von-Karman's equilibrium equations and also boundary conditions with finite Legendre basis functions that are substituted into the displacement fields. Due to effect of geometric nonlinearity, the final set of equilibrium equations is nonlinear and therefore the quadratic extrapolation technique is used to solve them. Since the number of equations in this approach will always be more than the number of unknown coefficients, the least squares technique will be used. Finally, the effects of boundary conditions, initial geometric imperfection and material properties are investigated and discussed to demonstrate the validity and capability of proposed method.

• Structural Engineering and Mechanics
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• 제47권2호
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• pp.247-263
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• 2013

It is evident that torsional resistance of a reinforced concrete (RC) member is attributed to both concrete and steel reinforcement. However, recent structural design codes neglect the contribution of concrete because of cracking. This paper reports on the results of an experimental and numerical investigation into the torsional capacity of concrete beams reinforced only by longitudinal rebars without transverse reinforcement. The experimental investigation involves six specimens tested under pure torsion. Each specimen was made using a cast-in-place concrete with different amounts of longitudinal reinforcements. To create the torsional moment, an eccentric load was applied at the end of the beam whereas the other end was fixed against twist, vertical, and transverse displacement. The experimental results were also compared with the results obtained from the nonlinear finite element analysis performed in ANSYS. The outcomes showed a good agreement between experimental and numerical investigation, indicating the capability of numerical analysis in predicting the torsional capacity of RC beams. Both experimental and numerical results showed a considerable torsional post-cracking resistance in high twist angle in test specimen. This post-cracking resistance is neglected in torsional design of RC members. This strength could be considered in the design of RC members subjected to torsion forces, leading to a more economical and precise design.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.228-228
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• 2006

Conjugated oligomers, used as models for fluorene-thiophene copolymers, are compared in terms of the microscopic morphology of thin deposits and the optical properties. The AFM images and the solid-state absorption and emission spectra are interpreted in line with the structural data, in terms of the assembly of the conjugated molecules. The compound with a terthiophene central unit and fluorene end-groups shows well-defined monolayer-by-monolayer assembly into micrometer-long strip-like structures, with a crystalline herringbone-type organization within the monolayers. Polarized confocal microscopy indicates a strong orientation of the crystalline domains within the stripes. In contrast, the compound with a terfluorene central unit and thiophene end groups forms no textured aggregates. The difference in behavior between the two compounds most probably originates from their different capability of forming densely-packed assemblies of ${\pi-pi}$ interacting molecules. These assemblies are used as active elements in organic field effect transistors designed by using soft lithography technique.

• 설비공학논문집
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• 제12권3호
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• pp.284-291
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• 2000

A basic pulse tube refrigerator has been constructed with extensive instrumentation to study the characteristics of the heat exchanger experimentally under the oscillating pressure and the oscillating flow. This paper describes the sequential experiments with the basic pulse tube refrigerator. The experiments were performed for various cycle frequencies under the square pressure wave forms. First, the heat flux was measured through the cycle at the both cold and warm end heat exchangers without the regenerator. In order to enhance the thermal communication capability of the heat exchanger with the gas at low operating frequencies, a unique design of the triangular shape radial fin concept was applied to the heat exchangers. For the fin heat exchanger, the measured heat flux and the calculated heat flux from the two well-known oscillating heat transfer correlations were compared and discussed. Second, the regenerator was added to the pulse tube to make a basic pulse tube refrigerator configuration. The experiment showed the great impact of the regenerator on the temperature and the heat flux profiles. At the warm-end, the cyclic averaged heat flux had its maximum value at the specific operating frequency. The paper presents the explanation of the surface heat pumping effect as well as the experimental data.

• 벤처창업연구
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• 제6권4호
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• pp.1-20
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• 2011

본 연구는 창업 여성CEO들을 대상으로 여성CEO의 특성과 경영성과 사이에는 어떤 상관성이 있는지에 대하여 살펴보고자 하였다. 이를 위하여 창업 여성CEO의 특성과 역량을 중심으로 하여 선행연구와 기존 문헌을 토대로 여성CEO의 특성요인으로서 경력 특성, 행위적 특성, 역량 특성 등 결정요인을 도출하고 이들 요인과 경영성과와의 관계에 대한 연구모형 과 가설을 설정하고 이를 실증적으로 분석, 검증하는데 연구의 목적을 두었다. 본 연구의 실증분석 결과는 다음과 같다. 첫째, 창업 여성CEO의 경력 특성과 경영성과간의 관계를 검증한 회귀분석 결과에서는 전공 요인은 유의미한 영향을 미치지만 직장 또는 창업경험 요인은 유의하지 않은 것으로 나타났다. 둘째, 창업 여성CEO의 행위적 특성과 경영성과 사이에서는 창업동기 요인은 유의미한 영향을 미치지만 실패 가능성이나 위험에 대한 대처 노력 요인은 유의하지 않은 것으로 나타났다. 셋째, 창업 여성CEO의 역량 특성과 경영성과에서는 관리적 역량 요인은 유의미한 영향을 미치지만 기업가적 역량 요인과 기술적 역량 요인은 유의하지 않은 것으로 나타났다.