• 한국조경학회지
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• 제20권1호
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• pp.39-52
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• 1992

In order to make plan for landscape construction by ecological methods in Yukong R & D Complex site, environmental factors and structure of plant community were investigated and analyzed around Yukong R & D Complex site of Daeduk. The result of this study were as follows: 1. In the result by the classification of TWINSPAN and ordination (DCA) techniques for analysing of plant community structure, thirty plant community structure, thirty plots were divided into four groups according to soil moisture and succession trends were seem to be from the development of subsidiary vegetation through Pinus densiflora, Quercus spp., Robinia psudoacasia community to Q. acutissima community. So this result was proposed to validity of vegetation introduction for planning of ecological landscape construction in studied site. 2. On the analysis of environmental factors by ordination techeniques, the plant community were divided by soil moisture. Soilcondition will be fertilized by introduction of broad-leaved tree and the development of succession trends from the present state of plant community to Q. acutissima community. 3. The problems of horiticultural places happened to studied site, so horiticultural places for ecological landscape construction was proposed planting techniques that were considered to soil suitability, economical efficiency, native species and wildlife. 4. If we attempt to ecological landscape designs on natural systems and use natural processes to achieve desired end-points, we are more likely to produce self-sustaining solutions.

• 약학회지
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• 제39권4호
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• pp.444-449
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• 1995

Primary cultures of rat cortical and chicken embryonic brain cells were employed to establish a reliable screening method for natural products blocldng or enhancing glutamate-induced neurotoxicity. Exposure of primary cultured rat cortical cells or chicken embryonic brain cells to high dose of glutamate resulted in the fragmentation of neutites and consequent neuronal death. The level of cytoplasmic lactate dehydrogenase(LDH), indicator for cell survival in cultures, was significantly reduced at exposure to glutamate. For the practical application of the methods, series of concentrations of plants extracts and positive control were applied prior to the glutamate insult on primary cultures of rat cortical and chicken embryonic, brain cells. Relative LDH level in cells was measured for the estimation of the effect of the test materials on the glutamatergic neurons. The validity of the present screening method for natural products acting on glutamatergic neurons was examined with dextromethorphan, a known glutamatergic antagonist. The treatment of 100 $\mu{M}$ dextromethorphan prevented the reduction of LDH in rat cortical and chicken embryonic brain cells caused by glutamate insult keeping 60% and 90% of LDH level in normal control, respectively. Above results indicate that primary cultures of rat cortical and chicken embryonic brain cells could be proper systems for the screening of potential natural agents acting on glutamatergic, neurons. Between the two types of cultures, primary culture of chicken embryonic brain cells seemed to be a better system for the primary screening, since it is technically easier and economical compared to that of rat cortical cells.

• 항공우주시스템공학회지
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• 제10권4호
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• pp.67-74
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• 2016

한국형 상태기준정비는 현재 한국해군 함정에 설치된 ICAS를 최대한 활용하여 전투준비태세를 완비하고, 선제적 정비/보급 지원과 군수자산의 경제적 운용, 데이터 기반 장비수명관리를 위한 것이다. 이러한 목적을 달성하기 위해서는 장비상태의 기준을 설정해야 하는데 이는 제작사에서 원천적인 기술을 제공하고 있지 않아 각 장비별 성능 맵 확보가 필요하고 고장패턴 등의 자료 축적이 필요하다. 본 연구에서는 소형 가스터빈엔진을 활용하여 가스터빈 성능 맵을 확인하고 고장정보를 축적하여 실시간으로 장비성능 확인과 성능 경향을 나타내게 하였고 이를 통해 운용자의 행동지침과 정비자의 검사 절차등을 명시하여 최적의 장비상태가 유지 될 수 있도록 솔루션을 개발하였다. 본 연구를 기반으로 실제 함정의 데이터를 이용한 상태진단기법 발전에 활용할 예정이다.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.283-290
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• 2006

Cable-stayed bridge is a bridge that consists of one or more pylons, with cables supporting the deck. Cable-stayed bridges have come into wide use recently because of their economy, stability, and excellent appearance. It is possible to achieve a uniform moment distribution in the stiffening girders mainly by prestressing the cables, which leads to a more economical design in material and weight than other types of bridges. However, to achieve a more uniform moment distribution is vague objective, so it cannot be easily defined as the optimization problem. In other words, the minimization of cost or weight as the objective is not directly related to the optimization of cable prestressing. Therefore, it has been considered as one of the most important, difficult and also interesting topics among many researchers and bridge engineers to determine the optimal tensioning strategy how to apply prestressing forces of the cables of cable-stayed bridge. A number of approaches (Wang et al. 1993, $Negr\~{a}o\;and\;Sim\~{o}es$ 1997, Agrawal 1997, Janjic et al. 2003) to determine the optimal cable tensions have been proposed in the literature. Among these approaches the unit load method (Janjic et al. 2003) is considered in this paper because it can take into account the actual construction process while other approaches are based on the configuration of the final structure only. In this paper, '2-step approach' based on the unit load method is proposed to find the optimal tensioning strategy especially for the atypical asymmetric bridge under construction, which has continuous deck supported by one pylon and stay cables. Some numerical results will be given to show the validity of the new approach suggested in this paper.

• Industrial Engineering and Management Systems
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• 제10권3호
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• pp.209-220
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• 2011

Self-tapping screws have some operational peculiarities. In spite of their economical advantage that requires no prior tapping operation, a weakness of self-tapping screw-tightening operations is that screws can easily be tightened at a non-right angle, thus resulting in an improper tightening strength. Increases in outsourced workers have reduced labor costs, but the accompanying high worker fluidity means that new workers are more frequently introduced into factories. It is necessary to train new workers for self-tapping screw-tightening operations, which occupies a considerable portion of ordinary assembly works. The purpose of this study is to develop and implement a skill transfer system for the operation. This study (1) proposes a set of characteristic values for evaluating the quality of the operation and develops a device that can measure these values; (2) proposes criteria for evaluating the resultant quality of the tightening; and (3) develops a skill training system for better work performance. Firstly, sets of characteristic values for evaluating the quality of the operation, namely, torque, vertical pressure forces and horizontal vibration forces, are proposed. A device that can measure these values is developed. Secondly, criteria for evaluating the resultant quality of the tightening are identified, involving tightening torque, maximum vertical pressure and timing, vibration area during the processing and tightening period, and work angle. By using such parameters, workers with the proper aptitude can be identified. Thirdly, a skill training system for the operation is developed. It consists of screwdriver operation training and screw-tightening training with feedback information about the results of the operation. Finally, the validity of the training system is experimentally verified using new operators and actual workers.

• 대한의용생체공학회:의공학회지
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• 제30권6호
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• pp.469-475
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• 2009

Diseases caused by indurate tissues of the internal organs are liver cirrhosis and abdominal sclerosis. The cause of chronic gastro-intestinal disease is a digestive system disorder and a defecation disorder. They impede peristaltic movement and digestive system with the symptom that indurate tissues. The purpose of the present study was to determine the disease grade quantitatively by measuring an indurated standard of tissues and organs. For the measurement of elasticity, we designed the system that measure the displacement of the substance and approved pressure using ultrasound transducer. For verification of developed system, we compared elasticity as results of experiment between the developed system and public elasticity measurement machine at individual plastic phantoms made by plastic hardener and softener. Elasticity of the plastic phantoms is averagely 0.007MPa lower measured by developed system than Micro-indenter, and less than 10% errors. Comparing with economical value and accuracy between developed system and Micro-indenter, the system is significant of measurement for tissue elasticity. Thus, it is possible to measure a elasticity at human tissue and organ. A chronic gastro-disease as well as grade could be decided objective validity using this system.

• 대한치과보철학회지
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• 제44권4호
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• pp.414-420
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• 2006

Purpose : The purpose of this study is to use finite element analysis to predict the fatigue life of an implant system subjected to fatigue load by mastication (chewing force). The reliability and the stability of implant system can be defined in terms of the fatigue strength. Not only an implant is expensive but also it is almost impossible to correct after it is inserted. From a bio-engineering standpoint, the fatigue strength of the dental implant system must be evaluated by simulation (FEA). Material and Methods Finite element analysis and fatigue test are performed to estimate the fatigue strength of the implant system. Mesh of implant is generated with the actual shape and size. In this paper, the fatigue strength of implant system is estimated. U-fit (T. Strong, Korea, internal type). The stress field in implant is calculated by elastic-plastic finite element analysis. The equivalent fatigue stress, considering the contact and preload stretching of a screw by torque for tightening an abutment, is obtained by means of Sine's method. To evaluate the reliability of the calculated fatigue strength, fatigue test is performed. Results: A comparison of the calculated fatigue strength with experimental data showed the validity and accuracy of the proposed method. The initiation points of the fatigue failure in the implant system exist in the region of high equivalent fatigue stress values. Conclusion: The above proposed method for fatigue life estimation tan be applied to other configurations of the differently designed and improved implant. In order to prove reliability of prototype implant, fatigue test should be executed. The proposed method is economical for the prediction of fatigue life because fatigue testing, which is time consuming and precision-dependent, is not required.

• 한국콘텐츠학회논문지
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• 제13권4호
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• pp.23-34
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• 2013

본 연구는 2012년 12월을 기준으로 디지털 전환이 완료된 시점에서 우리나라 유료방송 가입가구의 약 절반에 해당하는 가구가 디지털 전환의 수혜를 입지 못하는 초유의 사태가 여전히 진행 중이며, 이로 인해 구체적인 대안으로 떠오르고 있는 클리어 쾀과 8VSB 전송방식의 도입이 과연 타당한가에 대해 검토하고자 했다. 검토결과, 별도의 셋톱박스가 필요없는 클리어 쾀과 8VSB 방식은 사업자와 시청자의 경제적 부담을 덜어주고, 디지털 기술에 소외되기 쉬운 정보소외 계층을 포함시킬 수 있다는 장점이 있지만 전체 유료시장이 저가화되거나 콘텐츠 사업자의 저작권을 침해하는 등 콘텐츠 산업에 부정적인 영향을 미칠 것이라는 문제가 수반된다. 이로 인해 정부는 최소한의 수혜가구와 최소 채널을 지정해서 디지털 전환에 차질이 없되 관련 사업에 피해가 가지 않는 방향으로 정책적 목표를 설정할 필요가 있지만 상기한 우려가 쉽게 사라지지 않은 상황이다. 이에 대해 방통위는 한시적으로 두 가지 방법에 대해 개방적인 태도를 취할 필요가 있으며, 디지털 전환이 어느 정도 완성된 시점에서는 재고해야 할 것으로 판단된다.

• 대한공간정보학회지
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• 제10권3호
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• pp.99-105
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• 2002

국토공간정보에 대한 수요의 증대와 다양화에 대응할 필요성으로 정부는 1995년 5월 제 1차 국가 지리정보시스템(NGIS) 기본계획을 수립하였다. 지금까지 총 7년여에 걸친 국가 지리정보시스템 사업을 통해 다양한 분야의 공간정보관련 사업을 추진하여 왔으나 투자의 효율성과 경제성 확보를 위한 과학적이며 계량적인 평가가 부족하여 투자 타당성분석 및 사업별 대안의 의사결정이 올바르게 시행되지 못하였다. 지리정보시스템(GIS)의 구축시 제안된 대안들의 효과나 비용을 각 항목별로 우선 순위를 결정하고 이를 토대로 최적의 사업을 결정하는 것은 사업의 타당성을 입증하고 예산의 효율성을 제고하는 기본적인 수단이다. 이와 같은 필요성에서 본 논문은 GIS의 구축시 관련된 세부 비용들에 대해 계층분석기법(AHP기법)을 적용하여 일반적인 GIS 사업의 추진 시 구성되는 비용별 중요도를 분석하여 보았다.

• 한국전자거래학회지
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• 제12권2호
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• pp.155-194
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• 2007

본 연구의 목적은 최근 급속히 확산되고 있는 유비쿼터스 컴퓨팅 관련 기술 개발의 기준이 되고 있는 UCT(Ubiquitous Computing Technology)기반 서비스 시나리오의 실질적인 구현 가능성을 종합적으로 평가하는 다면평가방법론을 제안하는 것이다. 다면평가는 제안된 UCT기반 서비스 시나리오에 대하여 기술성, 사업성, 수용성의 3차원으로 평가하여 개별 시나리오의 구현 가능성 및 타당성에 대한 종합적인 평가를 가능하게 해주는 평가방법론이다. 이것은 기존 UCT기반 서비스 시나리오 관련 평가방법론의 부재를 극복하기 위해 제안되었다. 또한 기존에 제안된 기술가치 평가, 재무적 평가(ROI, ROA 등) 등 현재 구현되지 않는 UCT기반 서비스 시나리오의 특성상 도출 불가능 하거나 그 의미를 부여하기 어려운 파라미터를 이용하는 평가 방법의 한계를 극복하기 위해 제안되었다. 따라서 이는 다양한 분야에서 제안되는 UCT기반 서비스 관련 시나리오에 대한 실현 가능성을 포괄적으로 평가하여 해당 시나리오에 기반한 기술 개발에 대한 타당성과 개발 우선순위를 결정하는 평가 도구로 활용 가능할 것이다.