• 대한조선학회지
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• 제27권1호
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• pp.45-56
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• 1990

본 해석에서는 압력용기를 설계하기 위하여 복합적층된 원통형 구각의 비선형 해석을 유한요소법으로 수행하였다. 적층순서의 변화에 따라 최소변위 또는 최대압력을 갖는 최적의 적층구조를 얻기 위하여 8절점 Isoparametric 격하요소를 사용하며 구조요소의 비선형거동은 Total Lagrangian 수식과 하중증분법을 적용하여 해석하며 평형반복수렴은 Newton-Raphson Method를 이용하였다. 선형해석의 경우에 9가지 적층구조를 선정하여 하중조건이 내압일때 최소변위를 나타내는 적층구조를 조사한 결과 $[50^{\circ}/-50^{\circ}]$의 최적구조를 구하였고 적층순서를 $[{\theta}^{\circ}/{-\theta}^{\circ}]$로 하여 비선형해석과 동시에 Quadratic Failure Criteria를 적용하였을 때 하중조건이 외압만을 고려하는 상태에서도 $\theta=50^{\circ}$가 최소 변위비를 나타내었고 외압과 축하중을 동시에 고려한 상태에서는 $\theta=90^{\circ}$였다.

• 한국전산구조공학회논문집
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• 제27권6호
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• pp.493-500
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• 2014

본 연구에서는 농업시설물 중 내재해형 비닐하우스와 축사에 대한 화산재 취약도를 평가하였다. 이들 농업시설물에 대한 화산재 취약도를 평가하기 위해 화산재 하중의 확률밀도함수와 대상 시설물 저항성능의 확률밀도함수를 비교하는 해석적 접근법 기반의 FOSM(first-order second-moment) 방법이 이용되었다. 화산재 취약도 평가를 위하여 폭과 높이 그리고 단면 및 재료적 특성이 상이한 6종의 내재해형 비닐하우스와 표준형, 해안형, 산간형으로 구분된 3종의 축사가 사용되었다. 또한 FOSM 방법으로 평가된 내재해형 비닐하우스와 축사의 취약도는 GEV(generalized extreme value) 분포함수의 모수 형태로 최적화된 후 데이터베이스화되었다. 본 연구에서 평가한 화산재 취약도는 백두산 화산분화에 따른 화산재 퇴적에 대한 농업시설물의 위험도 평가를 위하여 활용될 수 있다.

• 한국빅데이터학회지
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• 제5권1호
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• pp.227-239
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• 2020

본 논문에서는 산업현장에서 통신 오류에도 불구하고 최대전력수요를 예측하는 방법을 소개한다. 최근 국내의 탈원전 정책으로 전력가격상승은 불가피하며, 이에 따른 전력수요 관리를 위한 전력사용량과 최대부하관리는 중요한 문제로 부상하고 있다. 이에 따라, 피크전력을 예측하고 관리하는 것이 중요하다. 하지만 실제 산업현장에서는 각종 설비 및 센서에서 발생하는 노이즈 등으로 인해 측정된 전력데이터의 손실 및 변조 등의 문제가 발생한다. 측정된 유효전력 데이터가 손실된 경우 정확한 값을 예측하기 어렵다. 이 연구는 측정된 유효전력 데이터가 손실될 경우 이상 징후와 결측값을 예측하고 수정하는 모델을 제시한다. 본 연구에 사용된 모델은 산업현장에서 통신 오류가 발생할 경우 최대 전력수요를 예측하는 데 유용할 것으로 예상한다.

• PNF and Movement
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• 제7권4호
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• pp.31-36
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• 2009

Many daily activities require people to complete a motor task while walking. Substantial gait decrements during simultaneous attention to a variety of cognitive tasks have been shown by a group of severely injured neurological patients of mixed etiology. And previous studies have shown that the attentional load of a walking-associated task increased with its level of difficulty. The purpose of this study was to analyze subjects' gait changes are affected by the effects of arithmetic task difficulty and performance level. Participants performed a walking task alone, three different Arithmetic tasks while seated, and among them, two kinds of the simillar Arithmetic tasks in combination with walking. Reaction time and accuracy were recorded for two of the Arithmetic tasks. The mean values of the gait were measured using a Timed Up and Go test among 11 with post-stroke patients while walking with and without forward counting (WFC) and backward counting(WBC).There was significant Arithmetic Task Difficulty level between the 10-forward counting task condition(FC) and the 10-backward counting task condition(BC)(p=0.008). The mean values of T.U.G time were significantly higher under backward counting dual-task condition than during a simple walking task(p=0.009) and WFC(p=0.009). The change in T.U.G time during WFC was higher when compared with the change during a simple walking, but there was no significant difference (p=0.246). This study suggesting that a high interference could be linked with a high level of difficulty, whereas adaptive task enabled participants to perfectly share their attention between two concurrent tasks. Future research should determine whether dual task training can reduce gait decrements in dual task situations in people after stroke. And the dual-task-based exercise program is feasible and beneficial for improving walking ability in subjects with stroke.

• 대한치과보철학회지
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• 제41권6호
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• pp.762-771
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• 2003

Statement of problem. In dentistry, the minimally prepared inlay resin-bonded fixed partial denture (FPD) made of new ceromer / fiber-reinforced composite (FRC) was recently introduced. However, the appropriate dimensions for the long-term success and subsequent failure strength are still unknown. Purpose. The aim of this study was to investigate the most fracture-resistible thickness combination of the ceromer / FRC using a universal testing machine and an AE analyzer. Material and Methods. A metal jig considering the dimensions of premolars and molars was milled and 56-epoxy resin dies, which had a similar elastic modulus to that of dentin, were duplicated. According to manufacturer's instructions, the FRC beams with various thicknesses (2 to 4 mm) were constructed and veneered with the 1 or 2 mm-thick ceromers. The fabricated FPDs were luted with resin cement on the resin dies and stored at room temperature for 72 hours. AE (acoustic emission) sensors were attached to both ends, the specimens were subjected to a compressive load until fracture at a crosshead speed of 0.5 mm/min. The AE and failure loads were recorded and analyzed statistically. Results. The results showed that the failure strength of the ceromer/FRC inlay FPDs was affected by the total thickness of the connectors rather than the ceromer to FRC ratio or the depth of the pulpal wall. Fracture was initiated from the interface and propagated into the ceromer layer regardless of the change in the ceromer / FRC ratio. Conclusion. Within the limitations of this study, the failure loads showed significant differences only in the case of different connector thicknesses, and no significant differences were found between the same connector thickness groups. The application of AE analysis method in a fiber-reinforced inlay FPD can be used to evaluate the fracture behavior and to analyze the precise fracture point.

• 한국태양에너지학회:학술대회논문집
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• 한국태양에너지학회 2009년도 추계학술발표대회 논문집
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• pp.92-97
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• 2009

It is more necessary to consider the various factors for developmenting visible PV module of alternative window than traditional PV module. It must have sufficient performance which is Tvis, daylighting, daylight factor, glare index. so that more needs to consider suitable plan and total evaluated technology. Under the this background. For using commonly a combination BIPV module system and Daylinghting that can alternative architectural window, our goal on this study is drawing proper window area ratio as the window by analyzing lighting performance and glare index depending on transmittance of DSSC. On this study, we drew the result about window area ratio that can apply in the building when applying DSSC in the window. In situation that window is alternated as curtain wall in atrium that has big Widow area, if applying red 15.8% DSSC of low transmittance, it is expect to proper because it is suitable illumination standard and doesn't occur a discomfort glare. In case of office, we propose to apply red 33.2% or blue 35.2% DSSC of high transmittance for no affecting lighting load. we expect to contribute to select proper and effective window when applying the window in the building by drawing the window area ratio that can apply in thee building depending on transmittance of DSSC and offering the glare index data.

• Steel and Composite Structures
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• 제25권1호
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• pp.117-126
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• 2017

The component method is an analytical approach for investigating the moment-rotation relationship of steel connections. In this study, the component method was improved from two aspects: (i) load analysis of mechanical model; and (ii) combination of spring elements. An optimized component method with more reasonable component models, spring arrangement position, and boundary conditions was developed using finite element analysis. An experimental testing program in two major-axis and two minor-axis connections under symmetrically loading was carried out to verify this method. The initial rotational stiffness obtained from the optimized component method was consistent with the experimental results. It can be concluded that (i) The coupling stiffness between column and beam flanges significantly affects the effective height of the tensile-column web. (ii) The mechanical properties of the bending components were obtained using an equivalent t-stub model considering the bending capacity of bolts. (iii) Using the optimized mechanical components, the initial rotational stiffness was accurately calculated using the spring system. (iv) The characteristics of moment-rotation relationship for beam to column connections were effectively expressed by the SPRING element analysis model using ABAQUS. The calculations are simpler, and the results are accurate.

• 대한치과보철학회지
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• 제30권4호
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• pp.611-621
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• 1992

저자는 두개의 브로네마트 임플란트를 지대치로 하는 가공의치를 제작할 때 임플란트의 길이에 따른 임플란트 주위 조직의 응력분산양상을 평가하기 위하여 임플란트의 길이가 각각 10mm, 7mm, 5mm인 여섯가지의 실험모형을 제작하고 가공의치 중아부에 64kg의 수직하중을 가하여 2차원적 광탄성응력분석 실험을 행하여 비교 분석 해본 바, 다음과 같은 결론을 얻었다. 1. 여섯가지 실험모형 중 응력분산 양상은 실험모형 I (10mm, 10mm)일 경우가 가장 좋았다. 2. 근심과 원심에 같은 길이의 임플란트를 매식하였을 경우, 응력은 대체로 임플란트 표면적의 감소에 비례하여 증가하였다. 3. 근심과 원심에 다른 길이의 임플란트를 매식하였을 경우, 짧은 쪽 임플란트의 경부에 응력이 집중되었다.

• Journal of Electrical Engineering and Technology
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• 제5권2호
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• pp.179-190
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• 2010

This paper describes a new stochastic heuristic algorithm in engineering problem optimization especially in power system applications. An improved particle swarm optimization (PSO) called adaptive particle swarm optimization (APSO), mixed with simulated annealing (SA), is introduced and referred to as APSO-SA. This algorithm uses a novel PSO algorithm (APSO) to increase the convergence rate and incorporate the ability of SA to avoid being trapped in a local optimum. The APSO-SA algorithm efficiency is verified using some benchmark functions. This paper presents the application of APSO-SA to find the optimal location, type and size of flexible AC transmission system devices. Two types of FACTS devices, the thyristor controlled series capacitor (TCSC) and the static VAR compensator (SVC), are considered. The main objectives of the presented method are increasing the voltage stability index and over load factor, decreasing the cost of investment and total real power losses in the power system. In this regard, two cases are considered: single-type devices (same type of FACTS devices) and multi-type devices (combination of TCSC, SVC). Using the proposed method, the locations, type and sizes of FACTS devices are obtained to reach the optimal objective function. The APSO-SA is used to solve the above non.linear programming optimization problem for better accuracy and fast convergence and its results are compared with results of conventional PSO. The presented method expands the search space, improves performance and accelerates to the speed convergence, in comparison with the conventional PSO algorithm. The optimization results are compared with the standard PSO method. This comparison confirms the efficiency and validity of the proposed method. The proposed approach is examined and tested on IEEE 14 bus systems by MATLAB software. Numerical results demonstrate that the APSO-SA is fast and has a much lower computational cost.

• 정보처리학회논문지C
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• 제9C권6호
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• pp.865-874
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• 2002

HTTP(HyperText Transfer Protocol)는 월드 와이드 웹 분산 시스템이 객체를 인출하기 위해 사용하는 전송 프로토콜이다. HTTP는 연결 지향 프로토콜이므로 트랜스포트계층에서 TCP(Transmission control Protocol)를 사용한다. 그러나 HTTP는 TCP와의 상호운용이 좋은 편이 아닌 것으로 알려져 있다. 본 연구에서는 TCP의 성능에 영향을 주는 요인들을 살펴보고, HTTP 접근을 위해 TCP의 slow-start 오버헤드 및 연결에 소요되는 트랜잭션 시간과 TCP의 성능 향상 대안중의 하나인 T-TCP(Transaction TCP)의 트랜잭션 시간을 검토한다. 평균 대기 시간과 평균 반환 시간은 사용자의 서비스 품질을 만족시키기 위한 중요한 파라메터들이다. TCP와 T-TCP 트랜잭션 시간이 주어지는 경우 그러한 파라메터들의 계산 공식이 유도되었다. 실험 및 계산 경험을 통해 제안된 공식이 잘 작동됨을 확인하였고, 대역폭의 확장이 필요한 환경에 적용될 수 있으며 T-TCP의 시간 특성이 TCP 보다 우수함을 확인하였다. 아울러, 평균 대기 시간과 평균 반환 시간을 줄이기 위해 대역폭을 조합하여 서버를 분산하는 방법이 제시되었다.