Refrigerators used in homes occupy a large portion of the power consumption. In addition, most of the power consumption of the refrigerator is used by the compressor. Therefore, it is necessary to study on the improvement of compressor efficiency to save energy. In this study, the suction system was changed to improve the efficiency of the linear compressor. For this, numerical analysis was performed by linking the 1 dimensional lumped model and the 2 dimensional axisymmetric CFD model. The numerical analysis results were also compared with the experimental results. As a result of the numerical analysis, the model with modified suction system increased EER by about 0.25% compared to the basic model, which was also confirmed by experiment.

In turbopump type liquid rocket engines, ignition and starting are known to be the most unstable and risky section among all operating sections of the projectile. The operation of the liquid rocket engine is the process of ignition and combustion of the main combustor after the turbo pump is driven into a stable section due to the turbine driving of the turbo pump and the ignition and combustion of the gas generator by the pyro starter. In this process, the driving of related components directly influences each other, so each component must be operated with sufficient reliability. In particular, if the igniter does not supply sufficient ignition energy at a predetermined time, an explosion may occur due to stagnation of the fuel/oxidant mixture, so reliability is more important. In this study, the fracture analysis of the gas generator igniter rupture disk according to the shape was performed using computational analysis. As a result, comparative analysis was performed to obtain the optimal dimensions according to each variable condition.

In this study, structural characteristics were analyzed by combining gravity load and lateral loads such as seismic loads through static analysis of example structures, and the static characteristics of the twisted structure according to the plane rotation angle were also analyzed. Example structures were selected as regular structure, and twisted structures; 1.0, 2.0, and 3.0 degree angle of rotation per story, and static analysis was performed by the load combination case 1 and case 2. As a result the story drift ratio of the twisted-shaped structure also increased as the plane rotation angle per story increased. The eccentricity according to the load combination was the highest in the lower stories of all analysis models, and the eccentricity was found to be larger as the rotation angle decreased. The twisted-shaped structure was more responsible for the bending moment of the column than the regular structure, and the vertical member axial force of all analysis models was almost similar.

In this study, the structural analyses were conducted for each model by applying the loads into the design of a large commercial truck seat. Model C with three vertical frames has the smallest total deformation among all models, indicating the strongest stiffness. The maximum total deformation of model C was shown to be 0.68 times smaller than that of model A and 0.79 times smaller than that of model B. The equivalent stress of model C was also shown to be the lowest, indicating the greatest stiffness. The maximum equivalent stress of model C was shown to be 0.8 times smaller than that of model A and 0.91 times smaller than that of model B. At the upper part of the seat or the part where the force was applied, all three models were shown to have the largest total deformations and equivalent stresses. If the result of this study is applied to the design of automotive seat frame, it is thought that the durable and rigid sheets can be manufactured efficiently. By utilizing this study result, the equivalent stress and total deformation are investigated without the real experiment by shape at the seat of large commercial truck, and the durability and rigidity can be seen.

In this study, the flow analyses were carried out on the electric train models with three kinds of mounting materials installed at the front part of train. By examining the results of flow rate and pressure, It was investigated which type of design should be designed to be more efficient in high-speed operation. The three types of models are set as models a, b and c, and each has its own shape. For all models, the wind speed was set at 110 km/h, the most common driving speed for wide-area electric trains. In the case of the model a, it was good at cutting the wind flow as a round shape when viewed from the top. But from the side, it showed a vortex forming in the upper corner. To the contrary, the model b, which has a wedge-shaped side, could be seen from the top as a result of a vortex. Finally, in the case of model c combined with models a and b, the least vortex, front pressure, and resistance forces were shown by selecting the flow advantages of models a and b. By utilizing this study result, the flow velocity and pressure are investigated without flow experiment by shape of the front part of electric train, and the flow capacity can be seen.

In this study, by analyzing the flow rate and the pressure applied to the fan for the flow of air with room temperature into the fan in desktop computer, it was investigated which model was suitable for flow resistance. When comparing the speed distribution of air flow by model according to fan shape, model A was able to confirm that the fan performance was not good but the external flow was widely distributed. And model B was able to know that the performance was good but the external flow was smaller. Model C was found to have good performance and a wide distribution of outer flow. In cases of three models, it was equally shown that the pressure was highest on the blade side of the inlet where the air enters. Model B receives more pressure than models A and C when the same air flow rate is applied, so models A and C are considered more efficient cooling fans than model B. When considering the flow rates and the pressures acting on the model, model C is thought to have relatively good performance. By utilizing this study result, the flow rate and pressure are investigated without flow experiment by the shape of fan in desktop computer, and the flow capacity can be seen.

In this study, the deformation, equivalent stress and strain energy were analyzed on the electric kick board emerging as a new means of transportation at the accident of a front collision according to each shape were analyzed. The largest part deformation happened at the handle, and the board part where the person’s feet was placed was seen to become weak. The equivalent stress was most visible at the board section, unlike the deformation results. In particular, the deformation and stress of model A which has a long and thin neck, have occurred greatly. Therefore, the longer the neck, the greater the deformation and stress occur. Among all models, the deformation and stress were the smallest at model C. As model A has a particularly thinner neck and board connection part, a large strain energy appeared. Therefore, it is considered that the connection needs to be reinforced thickly and firmly. On the study result, the thicker the board part of the electric kick board and the lower the body of the vehicle, the safer it is. The results of this study can be effectively applied to investigate the values of stresses and deformations, and strain energies through structural analysis without the fracture test at the front collision according to the shape of electric kick board.

In this study, the structural and fatigue analyses were carried out according to the shape of the self-made car frame. As a result of structural analysis, all models are shown to have the weak strength and large deformation, as the equivalent stress increases at the forward part of the impact force. It can be seen that model 3 is deformed less than other models 1 or 2. And model 3 with the truss structure prevents the great deformation from the collision. In case of irregular fatigue loads, the fatigue life of the ‘Sample history’ increased by about 59.3 times compared to the ‘SAE bracket history’ under extreme fatigue load conditions, indicating that the fatigue load condition of the ‘Sample history’ were stable. The fatigue life and deformation of model 3 among all models are significantly different to models 1 and 2. If the research results are applied to the design of self-made cars, it will be useful for improving the durability and preventing the damage. The results of this study can be effectively utilized to investigate the values of stresses and deformations, and fatigue lives without the experiments of fracture and fatigue according to the shape of the car frame.

우리나라는 지진에 대해 비교적 안전한 지역으로 인식되고 있었으나, 최근 경주지진과 포항지진이 발생하면서 시설물에 상당한 피해가 발생되면서 지진피해 저감장치를 적용한 내진설계 및 보강에 대한 연구와 개발이 수행되고 있다. 이미 건축된 구조물의 유지⋅보수에 대한 관심이 높아짐에 따라, 구조물의 감쇠, 강성 등을 국부적으로 변화시켜 지진 하중에 의한 에너지를 흡수하고 소산시키는 내진설계 방식인 제진기술이 활용되고 있다. 그러나 강한 지진이 발생할 때 제진 장치의 손상으로 인하여 사용성이 매우 떨어지게 되는 문제점이 발생되고 있다. 최근에는 이러한 문제를 해결하기 위해, 구조물의 가새 부재에 별도의 열처리를 하지 않고 응력 제거만으로 원형복원이 가능한 초탄성 형상기억합금을 적용하는 연구가 진행되고 있다. 따라서 본 연구에서는 비좌굴 가새 부재에 초탄성 형상기억합금을 사용하여 자동복원이 가능한 프레임 구조물을 구성하여 비선형 정적해석을 수행하여 구조물의 내진성능을 평가하고, 초탄성 형상기억합금의 재료적 특성의 우수성을 검증하고자 한다.

이 연구는 D시에 근무하는 공무원 998명(남성:615명, 여성:383명)을 대상으로 체형분석을 통해 체형 불균형 정도를 평가하고자 하였다. 이 연구에 참여한 연구대상자의 직장근무경력은 남성 21.1±8.4년, 여성 18.5±9.6년이며, 평균연령은 남성:47.4±7세; 여성:43.8±8.4세이다. 연구 결과로 통증이 있거나 좋지 않은 부위가 있는 남성은 416명으로 전체 남성의 67.6%, 여성은 297명으로 전체 여성의 77.5%로 여성 직원이 남성 직원보다 약 10%정도 높은 비율로 근골격계 통증을 호소하고 있었다. 또한, 규칙적인 운동을 하고 있는 직원은 남성 293명(47.6%), 여성 168명(43.9%)으로 조사되었다. 정적체형 측정(관 상면, 시상면) 결과 통증이 있는 남성 416명 중 비운동자 322(52.4%)명의 목의 긴장도를 살펴본 결과 4.54±2.6kg이었고, 통증이 있는 여성 297명 중 비운동자 215명(56.1%)의 목의 긴장도는 2.47±1.5kg로 나타났다. 이러한 연구 결과를 토대로 오랫동안 앉아서 근무하는 대표적인 직업형태인 공무원은 자세 습관, 운동습관 등이 일자목과 같은 체형불균형에 상당 연관성이 있으며 이러한 체형불균형은 근골격 계 질환에도 영향을 미칠 수 있다는 것을 확인할 수 있었다.

Modularization is an important benefit to overall project cost, such as construction period, manpower and logistics. In order to establish a successful modularization strategy, the optimum cost can be realized based on the Envelope Size which is allowed to be transferred to the plant site through analysis of each shape of the module. Through the analysis of the plant structure, the Envelope Size that can be transported on site in units of sizes suitable for maritime and onshore is provided, and finite element method is applied to the existing materials (A36, A572) and domestic materials (SS400, SM490, SWH400) and analyzed the results of the analysis to obtain domestic materials applicable to the plant structure frame.

The wavy fins have been widely used in the heat exchangers in coolering system, aerospace system and automotive. Especially, an automobile has the wavy fin and flat tube heat exchanger for oil cooling system. The objective of this research is the performance comparison of wavy fins for battle vehicle diesel engine oil-cooler by numerical analysis. The real type fin is the wavy fin with corrugated structure, and the comparative fin surfaces are plain, louver, lateral perforation and parallel wavy fin. The non-dimensional values of f-factor, j-factor, area goodness factor and volume goodness factor was performed on the performance comparison. The plain and louver fin shows the highest performance in pressure drop and heat transfer respectively. In the area goodness factor and volume goodness factor results, the parallel wavy fin and louver fin show the highest values at each result.

청정소화약제는 지구오존층 보호를 위해 발효된 몬트리올 의정서에 따라 할론 1211 및 할론 1310을 대체할 수 있는 약제를 말한다. 국·내외적으로는 청정소화약의 시스템 표준화와 성능평가가 수행되고 있다. 본 논문은 일반적인 청정소화약제 시스템을 바탕으로 다양한 노즐의 형상에 대한 모델링 및 수치해석을 수행하여 최적의 노즐 형상을 제안하였다. Type A와 B의 2가지 형상에 대한 노즐의 3차원 모델링을 통해 노즐의 분출속도가 개선될 수 있도록 하였다. 2가지 형상의 노즐에 대하여 유동해석을 실시하였으며 노즐의 홀 직경을 다르게 하여 가스속도 및 압력분포를 측정하였다. 측정결과 노즐 홀 수 및 직경에 따라 노즐출구에서 분출속도가 달라지는 것을 확인할 수 있었으며 노즐 홀 직경에 관계없이 유량은 압력이 증가함에 따라 증가하는 경향을 나타내었다. 실험을 통해 얻어진 결과를 바탕으로 노즐 직경이 5 mm인 경우의 K-factor값이 101.8 l/min·bar-0.5임을 확인하였으며, 최종적으로 노즐 홀 5 mm인 12개의 홀이 2층 구조로 되어있는 형상의 노즐을 제안하였다.

니티놀이라고 하는 니켈-티타늄 형태의 형상기억 합금(SMA)은 상당한 양의 변형이 발생한 후에 추가적인 열을 가하지 않더라도 상온에서 원래 모양으로 복원될 수 있는 초탄성 효과를 가진다. 이러한 독특한 재료 특성 때문에, 니티놀은은 의료, 전기, 전자 및 기계 분야뿐만 아니라 토목 공학 분야의 내진 개량을 위한 변위 제어 장치로 널리 사용되어 왔다. 탄소강과 달리 초탄성 형상기억합금은 피로 저항성이 강하며 하중 속도에 따라 강성(하중-변위특성)등의 기계적 물성치가 변화한다. 본 연구에서는 하중 사이클의 반복 횟수와 속도에 따라 초탄성 형상기억합금의 기계적 물성치가 어떻게 변하는가에 대한 실험적 연구를 수행하였다. 본 연구로 인해 표준화된 초탄성 형상기억합금의 기계적 물성치는 이후 초탄성 형상기억합금을 적용한 내진 장치의 설계과정에서 활용함으로써 설계 효율성을 높일 수 있을 것으로 기대된다.

본 논문은 아이소-지오메트릭 해석에서 h-세분화를 이용한 국부 세분화법과 이에 따른 설계 민감도 해석의 방법론을 연 구하였다. 다중 조밀도 방식을 이용하여 경계면에서 변위 적합조건을 만족하였고, 기존의 아이소-지오메트릭 해석의 텐서곱 으로 인해 발생하는 원치 않는 자유도 증가의 문제를 극복하였다. 해석에서의 변위 적합조건과 마찬가지로, 설계 민감도 해석에서도 변위 결과와 마찬가지로 똑같은 적합조건을 만족하도록 하는 방법론을 제시하였다. 수치 예제를 통하여 본 방법론의 효율성을 입증하였고, 특별히 응력 집중 문제에서의 결과와 민감도 값을 비교하며 경계면에서의 적합조건을 확인하였다.

In ancient Chinese religion peoples prayed powerful spirits of nature, for example 祟•蠱• , these are the scourge that the insect as evil spirit brings. The magic ritual is done for such scourge． The city and feudal system associated with the establishment of royalty developed, along with the formof ritual changed, the blade statement concerning ritual such as 祭•祀and such as 史•使•事that means sacrificial rituals appeared. Further 師•追 that uses 𠂤; (that means festival meats) and 降•隠•際 that uses 阝(that means god ladders) as the characteristic theory of Dr.Sirakawa is considered．