• Elastomers and Composites
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• v.35 no.1
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• pp.29-37
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• 2000

In this study as a basic research of the elastomer, we show the results of the behavior of the two different chain length polymers in the melt confined between two impenetrable planes. The cubic lattice simulations are conducted in the canonical ensemble with a method that is a combination of reptation and crackshaft bond flip motions. A total of 680 chains which are 544 short chains comprising 10 beads and 136 long chains comprising 160 beads were placed in 20 lattice layers. It was assumed that there is no energetic interactions between covalently connected beads. while all other neighbors will interact with a truncated 6-12 Lennard-Jones potential. From the analysis of the simulation results, it was shown that purely entropic effects caused the shorter chains to partition preferentially to the surface. We also showed that the center of mass density of the shorter chains shows maximum near the surface. This is the opposite phenomena when compared to that of the longer chains. However, the segments of the shorter and the longer chains did not display any significant changes in bond order.

• Journal of Broadcast Engineering
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• v.22 no.5
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• pp.608-617
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• 2017

Methods of contrast enhancement have problem such as side effect of over-enhancement with non-gaussian histogram distribution, tradeoff enhancement efficiency against brightness preserving. In order to enhance contrast at various histogram distribution, segmentation to region with gaussian distribution and then enhance contrast each region. First, we segment an image into several regions using GMM(Gaussian Mixture Model)fitting by that k-mean clustering and EM(Expectation-Maximization) in $L^*a^*b^*$ color space. As a result region segmentation, we get the region map and probability map. Then we apply local contrast enhancement algorithm that mean shift to minimum overlapping of each region and preserve brightness histogram equalization. Experiment result show that proposed region based contrast enhancement method compare to the conventional method as AMBE(AbsoluteMean Brightness Error) and AE(Average Entropy), brightness is maintained and represented detail information.

• Journal of Families and Better Life
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• v.8 no.1
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• pp.157-170
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• 1990

본 연구는 미 L-A에 거주하는 한국이민 노인들의 특성을 파악하고, 그들의 생활만족도에 기여하는 결정요소들이 무엇인지 가려내며, 그 얻어진 결과를, 동일한 시각과 접근으로 시도되었던 미국 노인들에 대한 선행연구들의 결과와 비교 분석하였다. 연구는 1986년 12월에서 1987년 2월까지 3개월간 미 L-A 카운티에서 거주하는 55세 이상의 한국 이민노인 390명을 대상으로 설문지 조사를 실시하여 그중 192명을 자료분석에 사용하였다. 단계별 중다 회귀분석의 결과, 활동성의 제약정도, 결혼상태, 재정적인 안정, 교육정도, 연령증가 등 5가지 변인들의 특별히 한국노인의 생활만족도가 강한 연관성이 있었고, 반면 자신들이 평가한 건강상태, 지인과의 사회적인 상호작용, 미국거주 년한 등은 노후생활의 안녕에 전혀 직접적인 영향력을 행사하지 못했다. 그러나 자신들이 평가하는 건강상태는, 활동성의 제약 등과 같은 다른 변인에 미치는 효과를 통해서 생활만족도에 간접적으로 강하게 영향을 미치고 있었다. 이러한 결과를 선행연구에서 나타난 서구나 미국노인의 생활만족도 결정의 세 요인인 건강상태, 사회경제적 지위, 사회적 활동성과 비교해 볼때, 사회적 활동성과 연령증가 변인에서 서로 상반되는 대조를 보이고 있었다. 즉, 백인노인들은 나이가 듦에 따라 생활만족도가 낮아지거나 혹은, 연령증가와 생활만족도 사이에 별로 유의할 만한 관계를 보이지 않고 있으나, 본 연구에서의 한국노인은 나이를 먹으면서 오히려 생활만족도가 높은 것으로 나타났다. 한편, 사회적 활동성은, 백인노인의 생활만족도에 긍정적 혹을 부정적으로 가장 강하게 영향을 미치는 요인중 하나임에 반하여, 한국노인들은 이것이 자신들의 생활만족에 중요한 것이라 믿고는 있었지만 실제 통계학적으로는 영향력을 행사하지 못하는 요인이었다. 주거환경(자식과의 동거여부) 역시, 이제껏 한국사회에서 기대되어왔던 통념과는 달리, 한국노인의 생활만족도에 아무런 영향을 주지 못하고 있었다.

• Journal of Gastric Cancer
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• v.8 no.2
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• pp.65-69
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• 2008

Surgery is the only curative modality for the treatment of gastric cancer. There has been no drastic improvement in the treatment of gastric cancer with chemotherapy. Clinical trials have attempted to demonstrate the benefit of the preoperative chemotherapy for gastric cancer. The benefit of the use of preoperative chemotherapy or chemoradiotherapy has been demonstrated for other solid cancers such as breast cancer, esophageal cancer and rectal cancer. Despite the rationale of the use of preoperative chemotherapy for patients with gastric cancer, the evidence of positive results with the use of preoperative chemotherapy has not been clear. Recently the British Medical Research Council Adjuvant Gastric Cancer Infusional Chemotherapy (MAGIC) study demonstrated the survival benefit of preoperative and postoperative chemotherapy. However, this study had several problems with the use of a heterogeneous population of patients, the method of surgery and the use of perioperative chemotherapy. Further studies with new drugs are warranted to determine the role of pre-operative chemotherapy for patients with gastric cancer.

• KDI Journal of Economic Policy
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• v.33 no.2
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• pp.41-79
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• 2011

This study examines the compensation scheme for the executives and risk-taking behavior in the Korean banks. Theoretically, shareholders prefer risky asset choice to the optimal one due to the limited liability feature of reward, and stock-based executive compensation may induce choices favorable to the shareholder. We empirically test this risk-taking hypothesis using Korean banks' data. Since only the stock option data is available under the current disclosure system, we limit our analysis to examine the relationship between the compensation through stock option and the risk of banks. The result provides no evidence that stock option compensations increase the risk of banks, which is contrary to the theoretical prediction and preceding studies in the US. This may be due to any factor that the executive reward data omit, or regulation effects on the bank management.

• Geotechnical Engineering
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• v.12 no.2
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• pp.85-94
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• 1996

Model pile tests, using a calibration chamber in which the stress state and the relative density can be controlled, were performed in order to study the effects of pile diameter on the plugging rate and bearing capacity of open-ended pile. The model piles used in the test series were devised so that the bearing capacity of an open-ended pile could be measured out into three components. The test results showed that fully plugging depth of an open -ended pile increased with increase in pile diameter and soil density. Moreover, it was found that unit plug capacity decreased with increase in pile diameter, though the penetration ratio or plugging rate of piles was constant. However, the existing formulae for estimation of plug capacity give plug capacity which is constant or increased with increase in pile diameter, when penetration ratio or plugging rate of piles is equal. Thus, it is proposed that the effect of pile diameter as well as plugging rate on bearing capacity of pile must be considered in plug capacity estimation.

• Aerospace Engineering and Technology
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• v.6 no.2
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• pp.211-218
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• 2007

Dual-polarization means to use two orthogonal polarizations, namely two independent channels in communication. This can be used to deal with high datarate caused by large amount of observed data in future LEO satellite. However, when two orthogonal polarizations are not perfectly independent to each other in practical, interference is probably raised in each channel, meaning that noise level in passband increases. XPD (Cross-Polarization Discrimination) is the ratio of the signal level at the output of a receiving antenna that is nominally co-polarized to the transmitting antenna to the output of a receiving antenna of the same gain but nominally orthogonal polarized to the transmitting antenna. In this paper, the influence of XPD on the communication between satellite and ground station was analyzed under the assumption that X-Band dual-polarization was applied to KOMPSAT-2 (KOrea Multi-Purpose SATellite-2). Through analysis, it was shown that more than 3dB of link margin was still achievable despite of worst axial ratio, 2.5dB, at ground station antenna when axial ratio of satellite antenna was about 0.5dB under 99% of environmental availability.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.445.2-445.2
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• 2014

표면 조직화의 목적은 태양전지 표면에서의 입사되는 빛의 반사율을 감소 시키고, 웨이퍼 내에서 빛의 통과 길이를 길게 하며, 흡수되는 빛의 양을 증가시키는 것이다. 본 연구에서는 여러 가지 표면 조직화 공정 기술을 이용하여 표면 형상에 따른 광 변환 효율에 대해 연구하였으며, 셀을 제작하여 전기적 특성과 광학적 특성의 상관관계를 분석하였다. KOH를 이용한 표면 조직화, 산 증기를 이용한 표면 조직화, 반응성 이온 식각을 이용한 표면 조직화, 금속 촉매 반응을 이용한 표면 조직화 공정 기술을 이용하여 표면 조직화 공정을 진행하였다. 셀 제작 결과, 반사도 결과와는 상반되는 결과를 얻을 수 있었다. 표면 조직화 형상에 따른 셀 효율의 변화는 도핑 프로파일과 표면 재결합 속도의 변화 때문이라 생각되며 더 명확한 분석을 위해 양자 효율을 측정하여 분석을 시도하였다. 표면 조직화 공정 기술별 도핑 프로파일을 보면 KOH를 이용한 표면 조직화 공정을 제외한 나머지 표면 조직화 공정들의 도핑 프로파일은 불균일하게 형성되어 있는 것을 확인 할 수 있다. 양자 효율 측정 결과 단파장 대역에서 낮은 응답특성을 가지는 것을 확인 할 수 있었다. 그 이유는 낮은 반사도를 가지는 표면 조직화 공정의 경우 나노사이즈의 구조를 갖기 때문에 균일한 도핑 프로파일을 얻지 못해 전자, 정공의 분리가 제대로 이루어지지 못하였고 표면 재결합 속도증가의 원인으로 단락전류와 개방전압이 낮아져 효율이 떨어진 것으로 판단된다. 결과적으로 낮은 반사율을 갖는 표면 조직화 공정도 중요하지만 표면 조직화 공정 기술에 따른 균일한 도핑 프로파일을 갖는 공정을 개발한다면 단파장 응답도가 향상되어 단락전류밀도와 개방전압 상승효과를 얻을 수 있을 것이라 판단된다.

• Journal of the Korea Institute of Building Construction
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• v.10 no.5
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• pp.75-86
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• 2010

The contract screening system is being introduced and operated as a model of advance budget reduction for local fiscal efficiency. But as the authority recognizes the contract screening system as a means of budget reduction, and companies recognize it as a means of budget curtailment, a contradictory understanding structure on the contract screening system is being formed. This research was prompted to propose a development method that will enable the contract screening system operating in Jeju Special Self-Governing Province to be appropriately established as a model of advance budget reduction. To achieve this, the operating status of the contract screening system was analyzed, and the recognition level on the contract screening system of the local government and companies was analyzed on the basis of contract screening data.

• Journal of Technology Innovation
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• v.20 no.1
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• pp.141-167
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• 2012

Along with technological innovation, successful market entry of a new product is important for sustainable innovation of a firm. In this paper, we examined factors that affect successful introduction of new branded drugs in pharmaceutical industry. Under competing theories of the first mover's advantage and the late mover's advantage, this research focuses on how latecomers can overcome the disadvantages of late entry and catch up to the market leader. First, late movers can absorb the knowledge leaked from pioneering product during the time lag between early entrants and late entrants. Therefore, the time lag provides late entrants an opportunity to catch-up to market leader by differentiating and improving the quality of new product. Second, superior marketing capability of late entrants can enhance the possibility of catching-up, by overcoming the consumer base of early entrants.