• 한국화재소방학회논문지
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• 제30권6호
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• pp.111-117
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• 2016

본 연구는 스프링클러 헤드 근처에서 형성되는 액막의 자유표면 유동에 대해 CFD 모델을 적용하여 해석하고 스프링클러의 초기분무 특성 예측을 위한 기존 이론식의 결과와 비교를 통해 이론 모델의 타당성을 검토하였다. CFD 해석은 상용 해석프로그램인 CFX 14.0을 이용하였으며 노즐과 디플렉터로 이루어진 단순형상에 대해 표준난류모델과 VOF법을 적용하여 해석을 수행하였다. 평판부의 디플렉터 끝단에서 속도분포는 CFD 해석과 경험식이 매우 잘 일치된 결과를 보였으나 기하학적 형상이 복잡한 부분에서는 속도분포의 차이를 보였다. 이론모델에서 예측된 평균액적크기는 실제 스프링클러 헤드에서 측정된 평균액적크기에 대한 이전 연구결과와 큰 차이를 보였다. 그러나 이론 모델은 스프링클러 헤드의 초기 액적형성과정의 메커니즘을 이해하고 실험적 접근이 용이하지 않은 상황에서 분무 액적의 특성을 예측하는데 유동한 도구로 활용될 수 있다.

• Steel and Composite Structures
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• 제36권3호
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• pp.321-337
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• 2020

Contemporary design and construction of steel-concrete composite structures employs the use of prefabricated concrete elements and demountable shear connectors in order to reduce the construction time and costs and enable dismantling of elements for their potential reuse at the end of life of buildings. Bolted shear connector with mechanical coupler is presented in this paper. The connector is assembled from mechanical coupler and rebar anchor, embedded in concrete, and steel bolt, used for connecting steel to concrete members. The behaviour and ultimate resistance of bolted connector with mechanical coupler in wide and narrow members were analysed based on push-out tests and FE analyses conducted in Abaqus software, with focus on concrete edge breakout and bolt shear failure modes. The effect of concrete strength, concrete edge distance and diameter and strength of bolts on failure modes and shear resistance was analysed. It was demonstrated that premature failure by breakout of concrete edge occurs when connectors are located 100 mm or closer from the edge in low-strength and normal-strength reinforced concrete. Furthermore, the paper presents a relatively simple model for hand calculation of concrete edge breakout resistance when bolted connectors with mechanical coupler are used. The model is based on the modification of prediction model used for cast-in and post-installed anchors loaded parallel to the edge, by implementing equivalent influence length of connector with variable diameter. Good agreement with test and FE results was obtained, thus confirming the validity of the proposed method.

• 한국운동역학회지
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• 제17권4호
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• pp.169-179
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• 2007

The purpose of this study was to investigate the relations between the segments of the body and to qualitatively analyze coordination pattern of joints and segments during Sweep Shot movement in Ice Hockey, by utilizing coordination variables was angle vs. angle plots. By the utilization the three dimensional anatomical angle cinematography, the angles of individual joint and segment according to sweep shot in ice hockey. The subjects of this study were five professional ice hockey players. The reflective makers were attached on anatomical boundary line of body. For the movement analysis three dimensional cinematographical method(APAS) was used and for the calculation of the kinematic variables a self developed program was used with the LabVIEW 6.1 graphical programming(Johnson, 1999) program. By using Eular's equations the three dimensional anatomical Cardan angles of the joint and ice hockey stick were defined. The three dimensional anatomical angular displacement and coordination pattern of trunk and Upper limb(shoulder-elbow, elbow-wrist linked system) showed important role of sweep shot in ice hockey. As the result of this paper, for the successful movement of sweep shot in ice hockey, it is most important role of coordination pattern of trunk-shoulder, shoulder-elbow and elbow-wrist. specially turnk movememt as a proximal segment. Coordination pattern of Upper Limb(upperarm-forearm-hand) of Sweep Shot movement in Ice Hockey that utilizes coordination variables seems to be one of useful research direction to understand basic control mechanisms of Ice hockey sweep shooting linked system skill. this study result showed flexion-extension, adduction-abduction and internal-external rotation of trunk are important role of power and shooting direction coordination pattern of upper Limb of Sweep Shot movement in Ice Hockey.

• International Journal of Fluid Machinery and Systems
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• 제8권1호
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• pp.46-54
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• 2015

Thrust-ring-pump is a kind of extreme-low specific speed centrifugal pump with special structure as numerous restrictions from thrust bearing and operation conditions of hydro-generator units. Because the oil circulatory and cooling system with thrust-ring-pump has a lot of advantages in maintenance and compactness in structure, it has widely been used in large and medium-sized hydro-generator units. Since the diameter and the speed of the thrust ring is limited by the generator set, the matching relationship between the flow passage inside the thrust ring (equivalent to impeller) and oil bath (equivalent to volute) has great influence on hydrodynamic performance of thrust-ring-pump. On another hand, the head and flow rate are varying with the operation conditions of hydro-generator units and the oil circulatory and cooling system. As so far, the empirical calculation method is employed during the actual engineering design, in order to guarantee the operating performance of the oil circulatory and cooling system with thrust-ring-pump at different conditions, a collaborative hydrodynamic design and optimization is purposed in this paper. Firstly, the head and flow rate at different conditions are decided by 1D flow numerical simulation of the oil circulatory and cooling system. Secondly, the flow passages of thrust-ring-pump are empirically designed under the restrictions of diameter and the speed of the thrust ring according to the head and flow rate from the simulation. Thirdly, the flow passage geometry matching optimization between thrust ring and oil bath is implemented by means of 3D flow simulation and performance prediction. Then, the pumps and the oil circulatory and cooling system are collaborative hydrodynamic optimized with predicted head-flow rate curve and the efficiency-flow rate curve of thrust-ring-pump. The presented methodology has been adopted by DFEM in design process of thrust-ring-pump and it shown can effectively improve the performance of whole system.

• 한국지진공학회논문집
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• 제22권1호
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• pp.15-22
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• 2018

Pseudo-static approach has been conventionally applied for the design of gravity type quay walls. In this method, seismic coefficient ($k_h$), expressed in terms of acceleration due to gravity, is used to convert the real dynamic behavior to an equivalent pseudo-static inertial force for seismic analysis and design. Therefore, the calculation of an appropriate $k_h$ considering frequency characteristics of input earthquake is critical for representing the real dynamic behavior. However, the definitions of $k_h$, which is used for simplified analysis in Korea, focuses only on convenience that is easy to use, and the frequency characteristics of input earthquake are not reflected in the $k_h$ definitions. This paper evaluates the influences of the frequency characteristics of input earthquake on $k_h$ by initially reviewing the $k_h$ definitions in the existing codes of Japan for port structures and then by performing a series of dynamic centrifuge tests on caisson gravity quay walls of different earthquake input motions (Ofunato, Hachinohe). A review of the existing codes and guidelines has shown that the $k_h$ values are differently estimated according to the frequency characteristics of input earthquake. On the other hand, based on the centrifuge tests, it was found that the permanent displacements of wall are more induced when long-period-dominant earthquake is applied.

• 대한조선학회지
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• 제27권4호
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• pp.51-57
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• 1990

구조물을 용접할 시에는 열전도에 따른 온도 분포의 불균일에 의해 구조물에서 잔류 응력 및 변형이 발생되게 된다. 열전도에 따른 구조물의 거동을 기술하기 위해서는 열탄소성해석이 필요하게 되는데, 본 연구에서는 1차원 적층보 이론을 이용해서 보의 변형 및 잔류 응력을 계산하였다. 기존의 1차원 열탄소성 해석에서는 용접 길이가 무한해야만 성립하는 평형조건을 이용하고 있고, 경계 조건이 적절히 반영되지 못하는 제한성이 있었다. 그러나 증분 유한 요소법에 기초한 적층보 이론은 이런 제한성을 극복할 수 있다. 2차원 열탄소성 해석에서는 자유도의 증가에 따라 계산 시간이 방대해 지고, 변형 계산시에는 부정확성이 있는데에 비하여 적층보 해석에서는 2차원 해석과 같이 보 깊이 방향의 재료 성질 변화도 고려할 수 있고, 2차원 해석에 비해 자유도가 대폭 감소되었으며, 변형 계산에서도 실험치와 잘 부합되고 있다.

• 대한가정학회지
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• 제12권2호
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• pp.563-580
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• 1974

A Study of the Emotionality of Child and Mother The purpose of this study is primarily to understand the emotional climate of child and mother, which is a significant factor in child study and the home life. A sample was collected from a total of 1,592 of whom 796 are elementary school children with their mothers. Of these 796 children 440 are fom private schools, 190 from public schools in Seoul. The rest are taken from a farming area, 100 kilometers from Seoul. The data was basically obtained through answers to a questionaire distributed in September 1973. In this study, the cross-sectional method, percentage calculation and chi-square test are adapted from factor analysis. With this limited amount of data special attention now, the following conclusions can be drawn from this analysis although special attention should be given in making any kind of generalization about the entire population. 1) Children's emotionality (a) There is a higher percentage of emotionally well-adjusted children as opposed to maladjusted children.(51%>11%) (b) There is no correlation between children's emotionality and the following factors: grade, sex, residential area, school records, and educational level of their mothers. 2) Mother's Emotionality (a) There are more mothers who consider themselves happy than unhappy.(49%>2%) On the other hand a higher percentage of mothers reported feelings of tension and insecurity as compared to those who had feelings of firm security(65%>5%) (b) There is a high correlationshionship between marital adjustment and marital happiness. In other words, the more adjusted, the happier. A high marital happiness has strong influence on the preference of sex, on children's adjustment to their friends, and their present living condition. (c) There is a close relationship between a high marital adjustment and the social development of a child: being fond of fathers, homelife, and the acquaintance with many friends. In the same way, the positive emotionality of a mother in raising her children and their school records are also important. 3) Emotional relationship between a mother and her chid There is a close bond of love and respect between a mother and her child. Moreover, a high frequence of close and open-minded communication exist between them in a family. It is evident that the emotional climate of the mother has a strong and powerful influence on her child.

• 한국전산구조공학회논문집
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• 제27권6호
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• pp.525-532
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• 2014

본 연구에서는 프리스트레스트 콘크리트 일방향 슬래브의 사용성 평가를 위한 처짐을 분석하기 위하여 유한요소법에 기반한 해석적 연구를 수행하였다. 유한요소 상용 프로그램을 이용한 해석결과와 실험결과를 비교하여 모델링의 타당성을 검증하였으며, 비교적 유사한 결과를 나타내었다. 또한, 콘크리트 압축강도, 편심 거리, 활하중, 그리고 긴장재의 배치형태에 따른 처짐을 분석하여 수계산 결과와 비교하였고, 회귀분석을 통해 변수들과 처짐 사이의 상관관계를 확인하였다. 그 결과, 콘크리트 압축강도가 클수록, 편심 거리가 클수록, 활하중이 작을수록 처짐이 감소하는 것을 확인하였으며, 직선형태의 처짐이 가장 작고 절곡형태의 처짐이 가장 큰 것을 확인하였다. 또한 회귀분석을 통해 콘크리트 압축강도와 편심 거리가 솟음값에 미치는 영향을 분석하였다.

• 대한기계학회논문집A
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• 제34권11호
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• pp.1691-1696
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• 2010

설계단계에서 시스템의 불확실성을 반영하려는 노력이 다양하게 이루어지고 있으며, 강건 최적설계 혹은 신뢰도 기반 최적설계는 이에 대한 대표적인 설계 방법론이다. 이러한 최적화 수식에는 성능함수의 평균, 표준편차와 확률제한조건이 목적함수와 제한조건으로 주로 활용된다. 그러므로, 이러한 통계적 특성치를 효과적으로 계산하는 것은 필수적이며, 더 나아가 최적화 과정에서 비선형 계획법이 일반적으로 활용되므로 민감도가 반드시 필요하다. 본 연구에서는 통계적 모멘트와 확률제한조건에 대해 적분 형태로 정의되는 민감도 수식을 비정규 분포로 확장하고자 한다. 얻어진 민감도 해석 결과는 통계적 모멘트와 손상확률이 설계점에서 계산된 경우, 민감도를 얻기 위해 추가로 성능함수를 계산할 필요가 없음을 보여주므로 효율성 측면에서 우수하다. 그러나, 민감도 수식이 성능함수와 확률밀도함수의 미분과정에서 얻어지는 함수의 곱으로 정의되므로, 동일한 수치적분 방법이 적용되는 경우 민감도 해석 결과는 통계적 모멘트 결과의 정확도에 미치지 못할 가능성이 있다.

• 지구물리와물리탐사
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• 제19권3호
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• pp.131-135
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• 2016

코어레이는 포트란 2008 표준에 도입된 병렬 연산 기법이다. 코어레이를 이용하면 간단한 문법으로 분산 메모리시스템에서 병렬 연산을 구현할 수 있다. 본 연구에서는 탄성파 자료 처리 프로그램에 코어레이와 MPI를 적용하여 병렬 처리 성능을 비교하고 이를 통해 코어레이의 적용 가능성을 살펴보았다. 파동 전파 모델링을 이용해 연산 성능을 비교하였고, 영역 분해 기법을 이용해 일대일 통신 성능을 비교하였다. 또한 거꿀 참 반사 보정 프로그램을 이용해 병렬 처리 성능을 비교하였다. 그 결과 연산 성능은 코어레이 프로그램과 MPI 프로그램에서 큰 차이가 없었지만 통신 성능은 MPI가 우수했다.