• 품질경영학회지
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• 제35권3호
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• pp.107-117
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• 2007

The fatigue has been considered the most failure mode of metal, ceramic, and composite materials. In this paper, numerical experiments to asses the usefulness of two Dixon's methods(small and large samples) and 14 S-N methods on assumptions of lognormal fatigue limit distribution under RFL(Random Fatigue Limit) model are conducted for staircase(or up-and-down) test and compared by MSE(Mean Squared Error) and bias for estimates of mean log-fatigue limit. Also, guidelines for staircase test plans to choose initial stress level and step size are recommended from numerical experiments including sensitivity analyses. In addition, the parametric bootstrap method to construct a confidence interval for the mean of log-fatigue limit by the percentile method using a transition probability matrix of Markov chain is presented and illustrated with an example.

• 한국운동역학회지
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• 제23권3호
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• pp.245-252
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• 2013

The purpose of this study was to analyze the effect that various loads have on the lower limb biomechanics. The following variables were measured and analyzed; performance time for each phase, lower limb moments and joint angles, and ground reaction forces. The kinematic and kinetic data was recorded by 2 force platforms and a motion capture system while 12 healthy adults in their twenties stepped down three steps under loads of 0%, 10%, 20% BW. Results are as follows. First, the different loading conditions did not seem to significantly affect the performance times and the joint angles. Second, the largest ground reaction forces were observed at the 1 step at the 10% BW condition. Finally, at the 0% BW loading condition the right hip extension moment was the smallest and the left hip flexion moment was the largest. The results show that there are not any significant changes in the biomechanics of the lower limbs under loading conditions up to 20% BW. Further investigations including more loading conditions with more weights and more additional steps analyzed are needed.

• Journal of Biosystems Engineering
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• 제35권3호
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• pp.151-157
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• 2010

The objective of this study was to analyze the factors affecting on fuel consumption of agricultural tractor. According to the statistical analysis, fuel consumption of agricultural tractor was considerably influenced by kind of operation, throttle engine speed and gear steps of tractor but much less by kind of soil. Specific fuel consumption of the tractor in plowing, dry paddy tilling, wet paddy tilling and wet paddy levelling was 0.33~0.36, 0.30~0.45, 0.19~0.34, 0.28~0.39 L/$kW{\cdot}h$, respectively, and $CO_2$ emission was 0.36~0.45, 0.35~0.58, 0.22~0.42, 0.24~0.37 kg/$kW{\cdot}h$, respectively. Specific fuel consumption and $CO_2$ emission increased as throttle engine speed increased but reversely proportional with gear step of tractor, by which one can reduce fuel consumption and $CO_2$ emission with practicing of "Gear up & Throttle Down" technique in paddy operations.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.967_968
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• 2009

For lighting application, high-power LED nowadays is driven at 350mA and a sensing resistor is used to provide feedback for LED-current regulation. This method adds an IR drop at the output branch, and limits power efficiency as LED current is large and keeps increasing. In this paper, a power efficient LED-current sensing circuit is proposed. The circuit does not use any sensing resistor but extracts LED-current information from the output capacitor of the driver. Controlling the brightness of LEDs requires a driver that provides a constant, regulated current. In one case, the converter may need to step down the input voltage, and, in another, it may need to boost up the output voltage. These situations often arise in applications with wide-ranging ""dirty"" input power sources, such as automotive systems. And, the driver topology must be able to generate a large enough output voltage to forward bias the LEDs. So, to provide this requirements, 13W prototype Buck-Boost Converter is used.

• 대한산업공학회지
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• 제16권2호
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• pp.135-147
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• 1990

A nuclear power plant can be viewed as a large complex man-machine system where high system reliability is obtained by ensuring that sub-systems are designed to operate at a very high level of performance. The chance of severe accident involving at least partial core-melt is very low but once it happens the consequence is very catastrophic. The prediction of risk in low probability, high-risk incidents must be examined in the contest of general engineering knowledge and operational experience. Engineering knowledge forms part of the prior information that must be quantified and then updated by statistical evidence gathered from operational experience. Recently, Bayesian procedures have been used to estimate rate of accident and to predict future risks. The Bayesian procedure has advantages in that it efficiently incorporates experts opinions and, if properly applied, it adaptively updates the model parameters such as the rate or probability of accidents. But at the same time it has the disadvantages of computational complexity. The predictive distribution for the time to next incident can not always be expected to end up with a nice closed form even with conjugate priors. Thus we often encounter a numerical integration problem with high dimensions to obtain a predictive distribution, which is practically unsolvable for a model that involves many parameters. In order to circumvent this difficulty, we propose a method of approximation that essentially breaks down a problem involving many integrations into several repetitive steps so that each step involves only a small number of integrations.

• Journal of information and communication convergence engineering
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• 제21권2호
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• pp.103-109
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• 2023

We investigated the antipodal-symmetric dispersion maps of a dispersion-managed link with a midway optical phase conjugator to compensate for the distorted 960 Gb/s wavelength division multiplexed (WDM) signal caused by these effects. The proposed antipodal-symmetric dispersion map has various shapes depending on the detailed design scheme. We confirmed that the dispersion-managed link designed with the dispersion map of the antipodal-symmetric structure is more advantageous than the conventional uniform dispersion map for compensating WDM channels. It was also confirmed that among the antipodal-symmetric structures, the dispersion map configured with the S-1-profile, in which S is inverted up and down, was more effective for distortion compensation than the dispersion map configured with the S-profile. In particular, we confirmed that the S-1-profile can broaden the optical pulse width intensively at a short transmission distance, more effectively compensating for the distorted WDM channel. Because this structure makes the intensity of the optical pulse relatively weak, it can decrease the nonlinear Kerr effect.

• Journal of Microbiology and Biotechnology
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• 제29권11호
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• pp.1817-1829
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• 2019

Porcine deltacoronavirus (PDCoV) is an emerging swine enteric coronavirus that causes diarrhea in neonatal piglets. Like other coronaviruses, PDCoV encodes at least three accessory or species-specific proteins; however, the biological roles of these proteins in PDCoV replication remain undetermined. As a first step toward understanding the biology of the PDCoV accessory proteins, we established a stable porcine cell line constitutively expressing the PDCoV NS7 protein in order to investigate the functional characteristics of NS7 for viral replication. Confocal microscopy and subcellular fractionation revealed that the NS7 protein was extensively distributed in the mitochondria. Proteomic analysis was then conducted to assess the expression dynamics of the host proteins in the PDCoV NS7-expressing cells. High-resolution two-dimensional gel electrophoresis initially identified 48 protein spots which were differentially expressed in the presence of NS7. Seven of these spots, including two up-regulated and five down-regulated protein spots, showed statistically significant alterations, and were selected for subsequent protein identification. The affected cellular proteins identified in this study were classified into functional groups involved in various cellular processes such as cytoskeleton networks and cell communication, metabolism, and protein biosynthesis. A substantial down-regulation of α-actinin-4 was confirmed in NS7-expressing and PDCoV-infected cells. These proteomic data will provide insights into the understanding of specific cellular responses to the accessory protein during PDCoV infection.

• 한국전통조경학회지
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• 제28권1호
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• pp.113-119
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• 2010

본 연구는 다랑이논의 조형성에 관한 연구로 경남지역 남해 가천다랑이논, 산청 임천다랑이논, 함양 마천다랑이논을 선정하여 자연경관의 조형 가능성을 모색하는 시도로 사례분석을 통하여 그 가능성을 제시하고자 하였다. 이론적 배경으로 자연경관의 연구 및 조형관련 연구를 살펴보았으며, 이를 바탕으로 자연경관을 조형화 시키기 위하여, 지형에서 나타나는 다랑이논의 자연경관적 특성과 공간적 특성에서 얻어진 다랑이논 지형의 특성을 모두 9개 항목으로 나누었다. 그 내용으로 (1) 다랑이논의 경사 완급을 나타내는 경사도, (2) 다랑이논 가장자리 선의 요철이 보여주는 굴곡도, (3) 상하 가장자리 선의 평행성정도, (4) 각 다랑이논 단면의 폭의 크기, (5) 전체 다랑이논의 넓이, (6) 상하 다랑이논의 높낮이 차이를 나타내는 단차, (7) 전체적 다랑이논의 외형적 형태가 지닌 이미지로서의 형상성, (8) 전체적 경관이 지닌 자연스러움과 인위성, (9) 다랑이논을 형성하고 있는 축석이나 토양의 부드러움, 전체적인 경관에서 풍기는 분위기 등이다. 사례대상지를 문헌조사와 현지답사, GIS를 통해 분석한 주요결과는 다음과 같다. 첫째, 다랑이논의 경사가 심할수록 축석의 단차가 높아지고 면적과 폭에서는 급경사일수록 좁아짐으로써, 경사와 단차이에서는 비례적 관계 경사를 나타내고, 다랑이논 부지의 면적과 폭에서는 반비례로 나타나는 것을 알 수 있었다. 둘째, 다랑이논을 바라볼 때 보여지는 대상물이 갖는 선적, 면적 요소와 중첩, 반복되는 변화, 계절에 따른 변화, 산세, 계곡과 하천 등 주변환경과의 연계로 인한 경관의 변화는 개인의 성향에 따라 다양한 형상으로 이미지화할 수 있을 것으로 사료된다. 셋째, 각 대상지에서 도출되는 공통적인 형태로 반복구성과 방향성, 운동성, 질서와 변화 등을 조형요소화 하는 것이 가능할 것으로 판단되었다. 본 논문은 자연경관을 대상으로 조형성을 표현하기 위한 기초자료 연구로서 사례대상지의 주변 환경을 조사 분석하였으며, 대상지의 환경적 아름다움을 하나의 조형요소로 일반화할 수 있는 가능성을 시도했다는데 의미가 있으며, 보다 정밀한 연구는 추후 과제로 남겨두기로 한다.

• 한국환경과학회지
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• 제18권4호
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• pp.463-471
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• 2009

A study on vegetation in the Mangyeong River and Dongjin River basins and the surrounding regions of the Saemangeum Reclaimed Land was conducted in a series of efforts to determine the expected ecological changes in the salt marshes, to restore their vegetation, to explore the restoring force of halophyte, to examine the community mechanism and, ultimately, to rehabilitate marshy land vegetation along the lakeside, coastal dune and salt marshes of the Saemangeum Project Area. The findings of the study may be summed up as follows: Five species such as Suaeda japonica, Salicornia herbacea, Atriplex gmelini, Aster tripolium and Suaeda asparagoides that are mostly distributed in the estuary of the Saemangeum Reclaimed Land were analyzed to examine the mechanism of halophyte to maintain their community. To find out the strategies of plants for survival and the cause of forming community structure, a research was made as for appearance ratio of biomass, root lengths and germination. With regard to biomasses of halophyte, the biomass of Suaeda japonica increases rapidly, while Salicornia herbacea adopts a strategy of unstable growth pattern by which the biomass increases slowly in parallel with its slow speed of growth since initial appearance of young sapling. In contrast, Suaeda asparagoides, Atriplex gmelini and Aster tripolium choose to adapt themselves to environment promptly by being transformed into life form of annual or biennial plant, a pattern that is presumed to be favorable and stable for survival in the later stage of growth. In short, there is a sharp distinction among the 5 species: i.e. Suaeda japonica that begins to grow fast in the length of surface and underground section but slows down from the mid-stage on; Salicornia herbacea that grows slowly in the beginning step but starts to step up from the middle onward; Atriplex gmelini and Aster tripolium growing slowly in the initial stage but fast later on; and Suaeda asparagoides that turns from the constant growth in the beginning to rapid growth in the later period. The outcomes of the analysis into status of growth and influencing factors of Suaeda japonica in the sowing field that is most widely prevalent in the Saemangeum Reclaimed Land as a sort of ecological pioneer in the salt marshes showed that the average size of grass lands, density and number of individuals increase in the natural sowing field as well as in the plowing field regardless of their physical as well as physico-chemical features of the soil as the season progresses from June to October of a year.

• 한국조경학회지
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• 제43권5호
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• pp.87-99
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• 2015

과거 하드웨어 중심의 하향식 농촌개발사업을 개선하고자 2000년대부터 소프트웨어 중심의 사업을 지향하였고, 지자체 주도의 마을만들기가 행해졌다. 하지만 지금까지의 마을만들기 사업들 역시 외형적으로는 상향식 개발구조를 보이지만, 실제적으로는 행정기관의 관여 아래 추진되는 하향식 추진절차를 벗어나지 못하고 있는 실정이다. 본 연구는 현재의 마을만들기 진행과정에서 한 단계 더 나아간 상향식 개발방식을 효과적으로 반영하기 위해 수행되었으며, 여러 사람이 같은 자격으로 모여 마을만들기에 참여할 수 있도록 '협업형 마을만들기'를 제시한다. 연구대상지는 거창군을 대상으로 하였다. 행정 관련 공무원과 1:1 인터뷰를 통해 현재 거창군 마을만들기의 현황 및 실태분석을 알아보고, 이장단 설문조사와 일반주민 심층면담을 통해 마을만들기에 대한 주민 인식을 선행조사하였다. 이를 바탕으로 관련 공무원, 전문가, 지역주민의 참석 하의 10회에 걸친 라운드테이블을 진행하여 거창군의 협업형 마을만들기 실천전략을 로컬푸드, 문화 복지, 귀농 귀촌, 마을개발, 도농교류의 5가지 핵심분야를 선정하였다. 또한, 이는 행정의 지속적인 협업체계 구축과 주민의 참여역량 강화 노력, 전문가의 체계적인 통합운영관리 지원을 통해 이루어져야 한다고 판단하였다. 이로서 거창군만의 협업형 마을만들기 실천전략을 모색하였으며, 향후 각 농촌지역에서 상향식 마을만들기를 진행하고 도입할 수 있기를 기대한다.