• 한국군사과학기술학회지
• /
• 제15권2호
• /
• pp.130-137
• /
• 2012

In this paper, a post-analysis of cooling system for infrared(IR) window was performed based on heating experiment of IR window system. We applied the same experimental conditions to analysis, and then validated the analysis technique by comparing numerical and experimental results. For an analysis software, we used a professional heat/fluid analysis program and the numerical and experimental results were in fairly good agreement. We investigated the effect of thermal transfer between the frame and IR window and also a cooling efficiency between fluid and structure in order to determine the proper parameters for the analysis. In this study, 100 % thermal transfer between the frame and IR window and 30 % cooling efficiency between fluid and structure have been proposed, which can be used in the future conceptual design and analysis of similar IR windows.

• 한국정밀공학회지
• /
• 제29권8호
• /
• pp.824-833
• /
• 2012

The shrinkage and the warpage of the moulded part are influenced by the design of the product and injection mould. In a flat part with a partly thick volume, the warpage of the flat part is created from the difference of the shrinkage between thin and thick regions. The warpage of the flat part with a partly thick volume can be reduced by a proper design of the cooling system in the injection mould. The goal of this paper is to design properly cooling channels of injection mould to manufacture a flat part with a partly thick volume. The conformal cooling channel is adopted to improve cooling characteristics of a region with the thick volume. The linear cooling channels are assigned to the other region. The proper design of the conformal cooling channels is obtained from three-dimensional injection molding analysis for various design alternatives. The moulding characteristics of the designed mould with both conformal and linear cooling channels are compared to those of the mould with linear cooling channels from viewpoints of temperature, shrinkage and warpage of the moulded part using numerical analysis. Injection mould with both conformal and linear cooling channels for the flat part with a partially thick volume is fabricated. In addition, injection moulding experiments are performed using the fabricated mould. From the results of the injection moulding experiments, it has been shown that the designed mould can successfully fabricate the flat part with a partially thick volume.

• 대한기계학회논문집A
• /
• 제34권10호
• /
• pp.1487-1492
• /
• 2010

본 논문의 목적은 3 차원 사출성형해석을 통한 냉장고 플라스틱 서랍 제작용 사출성형 금형의 형상적응형 냉각수로 설계이다. 바람직한 형상적응형 냉각수로의 설계를 얻기 위하여 형상적응형 냉각수로의 직경과 위치가 사출성형 특성과 제품의 품질에 미치는 영향을 정량적으로 고찰하였다. 해석결과로부터 제품의 균일 냉각과 변형 최소화가 가능한 최적의 형상적응형 냉각수로의 설계를 도출할 수 있었다. 본 연구에서 제안된 사출성형 금형과 기존의 직선형 냉각수로의 사출성형 금형을 냉각/제품 제작 시간 및 제품 품질 측면에서 비교한 결과, 형상적응형 냉각수로를 가진 사출성형 금형이 제품의 생산성과 품질을 동시에 향상시킬 수 있음을 알 수 있었다.

• 한국산학기술학회논문지
• /
• 제15권3호
• /
• pp.1265-1271
• /
• 2014

노광기의 램프 냉각은 노광성능 및 기기수명에 큰 영향을 미친다. 본 논문에서는 노광장치로 유입되는 냉각공기의 속도를 도출하기 위해 램프하우징 내부의 열유동 해석을 수행하였다. 램프하우징의 냉각성능은 하부와 측면의 냉각 공기 속도에 의해 영향을 받는다. 하부 및 측면의 냉각 공기 속도를 독립변수로 설정하고, 상부 반사경 온도, 타원경의 온도 및 상부 배출공기의 온도를 종속변수로 설정하였다. 효율적인 냉각 해석을 위해 반응표면분석법에 의해 해석 조건을 설정하였다. 설정된 조건에 따라 해석을 수행하였으며, 수행된 결과를 바탕으로 냉각 공기 속도에 따른 램프 하우징 주요부 온도를 예측할 수 있는 회귀식을 도출하였다. 또한 종속변수를 목표온도까지 냉각하기 위한 냉각공기의 유입속도를 설정하였다.

• 대한기계학회논문집A
• /
• 제21권11호
• /
• pp.1773-1785
• /
• 1997

The cooling stage is the very critical and most time consuming stage of the injection molding process, thus it cleary affects both the productivity and the part quality. Even through there are several commercialized package programs available in the injection molding industry to analyze the cooling performance of the injection molding coling stage, optimization of the cooling system has npt yet been accomplished in the literature due to the difficulty in the sensitivity analysis. However, it would be greatly desirable for the mold cooling system designers to have a computer aided design system for the cooling stage. With this in mind, the present study has successfully developed an interated computer aided design system for the injection molding cooling system. The CAD system utilizes the sensitivity analysis via a Boundary Element Method, which we recently developed, and the well-known CONMIN alforuthm as an optimization technique to minimize a weighted combination (objective function) of the temperature non-uniformity over the part surface and the cooling time related to the productivity with side constranits for the design reality. In the proposed objective function , the weighting parameter between the temperature non-uniiformity abd the cooling time can be adjusted according to user's interest. In this cooling system optimization, various design variable are considered as follows : (i) (design variables related to processing conditions) inlet coolant bulk temperature and volumetric flow rate of each cooling channel, and (ii) (design variables related to mold cooling system design) radius and location of each cooling channel. For this optimum design problem, three different radius and location of each cooling channel. For this optimum design problem, three different strategies are suffested based upon the nature of design variables. Three sample problems were successfully solved to demonstrated the efficiency and the usefulness of the CAD system.

• 한국자동차공학회논문집
• /
• 제21권6호
• /
• pp.72-80
• /
• 2013

For the proper cooling of in-wheel motor, the cooling channel should have the characteristics which are low pressure drop and adequate cooling oil supply to motor part. In this study, the flow performance of cooling channel for in-wheel motor was evaluated and the shape of the channel was optimized. First, the pressure drop and flow distribution characteristics of the initial channel model were evaluated using numerical analysis. Also, by the result of analysis and design modification, 4 design parameters of the channel were selected. Second, using the Taguchi optimal method, the cooling channel was optimized. In the method, nine models with different levels of the design parameters were generated and the flow characteristics of each models was estimated. Base on the result, the main effect of the design parameters was founded and optimized model was obtained. For the optimized model, the pressure drop and oil flow rate were about 0.196 bar and 0.207 L/min, respectively. The pressure drop decreased by about 0.3 bar and the oil flow rate to the motor part increased by about 0.2 L/min compared to the initial model.

• 설비공학논문집
• /
• 제28권5호
• /
• pp.178-185
• /
• 2016

This study describes the analysis of a 20 MW chilled water plant used for the IT cooling of a recently constructed data center in Korea. The CFD model was developed with the aim of evaluating the impact of problems such as chiller failure on the water and air temperatures in the cooling system. The numerical model includes the chilled water hydraulic network and individual water-to-air CRAC units. The coupling between the IT server room air temperature levels and the cooling plant has enabled a full assessment of the cooling system design in response to system fault conditions to be performed. The paper examines an emergency situation involving the failure of the cooling plant, and shows how the inherent thermal inertia of the system along with additional inertia achieved through buffer systems allowed a suitable design to be achieved.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2001년도 추계학술대회논문집B
• /
• pp.405-409
• /
• 2001

An experimental analysis of the flow inside the refrigeration compartment of a home refrigerator was conducted in order to achieve better performances in terms of uniform temperature distribution and cooling speed. 2D PIV and stereoscopic PIV were used for the experiments on an actual-size refrigerator at operating conditions. Two CCD cameras were employed for a wider field of view in the measurement of the shelf, and stereoscopic PIV was used to measure the three velocity components at the various cooling duct outlets and the mean velocity fields were area-integrated to calculate the flow-rates. 50 to 100 instantaneous velocity fields were time averaged for the mean velocity fields. With the result of this analysis, a new cooling duct system was developed, with the refrigerator's cooling performance increasing 11% in terms of cooling speed, and 25% in temperature uniformity.

• 대한기계학회논문집B
• /
• 제33권1호
• /
• pp.17-27
• /
• 2009

Water jet impingement cooling is used to remove heat from high-temperature surfaces such as hot steel plates in the steel manufacturing process (thermo-mechanical cooling process; TMCP). In those processes, uniform cooling is the most critical factor to ensure high strength steel and good quality. In this study, experiments are performed to measure the heat transfer coefficient together with the inverse heat conduction problem (IHCP) analysis for a plate cooled by planar water jet. In the inverse heat transfer analysis, spatial and temporal variations of heat transfer coefficient, with no information regarding its functional form, are determined by employing the conjugate gradient method with an adjoint problem. To estimate the two dimensional distribution of heat transfer coefficient and heat flux for planar waterjet cooling, eight thermo-couple are installed inside the plate. The results show that heat transfer coefficient is approximately uniform in the span-wise direction in the early stage of cooling. In the later stage where the forced-convection effect is important, the heat transfer coefficient becomes larger in the edge region. The surface temperature vs. heat flux characteristics are also investigated for the entire boiling regimes. In addition, the heat transfer rate for the two different plate geometries are compared at the same Reynolds number.

• 한국의상디자인학회지
• /
• 제16권2호
• /
• pp.55-70
• /
• 2014

The purpose of this study was to investigate purchasing behaviors of summer clothes using cooling textiles and clothing design preference in summer season. The subjects were 623 married women aged from 30s to 60s. The research method was a survey and the measuring instruments consisted of purchasing behaviors of summer clothes using cooling textiles, clothing design preference in summer season, and subjects' demographics attributions. The data were analyzed by frequency analysis, multiple response analysis, cross tabs analysis, and $x^2$ test, using SPSS statistical program. The results were as follows. First, important clothing selection criteria were design, price, and textiles. The main items using cooling textiles that female consumers purchased were T-shirts, pants, and outdoor & sportswear. Main information sources of summer clothes using cooling textiles were internet and store display, and purchasing places were fashion outlet, internet, brand store, and department store. Second, female consumers most preferred comfortable and casual style. They mainly preferred white and blue color, pastel and pale tone, plain pattern, and cotton and functional materials in summer season. Third, there were many important differences among 4 age groups on purchasing behaviors of summer clothes using cooling textiles and design preference in summer season.