Heat transfer and pressure drop of horizontal heat exchangers with different configurations and installations numerically characterized. Three different heat exchangers were used and shaped as linear, wavy, and horizontal slinky, respectively. Installation depth was set from 0.5m to 3.0m and pipe spacing was ranged from 0.3m to 2.1m. The results showed that heat transfer rate and pressure drop were increased with the increase in the installation depth and the pipe spacing. The horizontal slinky heat exchanger carried more heat compared to others due to the greater effective heat transfer surface area per installation area. In terms of a ratio of heat transfer rate to pressure drop indicating the system efficiency, the linear heat exchanger performed better than others. On the other hand, the horizontal slinky heat exchanger was the most effective with respect to a ratio of heat transfer rate to installation cost.

This paper is concerned to develop a fluid pressure system for the control of artificial bladder urine discharge. The primary goal is to force the fluid into the space between the inner wall and the outer wall by using a pump in the artificial bladder having a double structure of inner and outer walls and to form the urine discharge pressure by the contraction of the bladder inner wall due to the movement of the fluid. The ANSYS_CFD analysis is used to confirm the delivery of fluid pressure in the artificial bladder model, and the ANSYS_FSI analysis is used to identify the deformation and internal pressure of the artificial bladder through the delivery of fluid pressure, and to identify the discharge of urine. As the design parameters of the modeling of the artificial bladder and the fluid flow field, the capacity of the flow field, and the pump pressure input value were selected.

In this study, the air-side cooling capacity and pressure drop of an evaporator for a refrigerator unit were experimentally investigated. Using the calorimeter, the performance of the evaporator was verified by changing the fin shape, fin pitch, tube row and air flow rate. The experimental apparatus consisted of the calorimeter which functioned as a constant temperature and humidity chamber and the refrigeration cycle. In order to select the heat exchanger suitable for the evaporator, both air-side cooling capacity and pressure drop should be considered at the same time. From the evaporator performance test by pin type, wavy pin was selected. The optimal performance of the evaporator was observed at the fin pitch of 5 mm, the tube row of 6 row, and the air flow rate of 40㎥/min.

本論文, 旨在要通過考察兩漢時期黃老學代表著作『淮南子』, 探討宇宙生成論的基本含義。宇宙生成論就探討如下幾個問題: 宇宙萬物之根源, 其根源如何發展到具體萬物, 天下萬物之最終根源是如何規定『淮南子』繼承了先秦時期老莊哲學思想、氣論和陰陽五行思想及兩漢時期所發展的自然科學之成果, 而使之適應於自己宇宙論體系之需要。.今爲止, 大多學者從以下方面起規定『淮南子』的宇宙生成論: 有些學者把『淮南子』規定爲‘雜家’而其理論體系最終落到於自相矛盾; .一些學者都從‘道’‘氣’.念的含義和兩者之間的關系問題出發, 建立起了其宇宙生成論的理解方式。從道氣兩個.念之間的關系問題上, 就發生了‘氣一元論’和‘以道爲主的自然觀’而再分爲‘道.氣’或‘道生氣’的觀點。那., 如何解釋『淮南子』所論的宇宙生成論才接近於其.正的含義? 筆者認爲,『淮南子』基本上堅持了宇宙萬物始於整體(‘一氣’)的立場。『淮南子』就把這種整體稱爲‘太昭=虛.=一’, 而從這個狀態起發生了‘陰陽二氣’的分化而最終形成了天地萬物。但在這個過程上, 我們必須解釋宇宙生成的動力是什., 因而『淮南子』提到了 ‘道始于虛.’、‘道始於一’的觀點。.是說, 道沒有直接參與於萬物生成過程, 而道就是所引起各個生成過程的基本動力, 所以『淮南子』把‘道’理解爲宇宙萬物的最終本原。如此, ..淮南子..就把‘道’和 ‘氣’綜合起來, 最終建立了‘以道爲本’的氣化宇宙論。對於向後中國哲學思想裏所發展的宇宙論體系, 『淮南子』的宇宙生成論.生了重大的影響。

본 연구는 산업용 열교환기 및 상용 파이프의 최적 설계를 위하여 열교환기 내의 사각형 단면 파이프의 shear-thickening 비뉴톤 유체의 압력강하 및 대류 열전달률을 수치해석적으로 수행하였다. shear-thickening 유체의 구성 방정식은 기존의 비뉴톤 유체 멱법칙을 보완한 확장 멱법칙 모델을 채택하였다. 파이프 내의 압력강하를 의미하는 마찰계수와 확장 레이놀즈 수의 곱은 기존 연구의 비교자료와 비교할 때 뉴톤 유체 영역과 멱법칙 영역에서 각각 0.018% 및 0.06% 내에서 일치함을 보였고, 대류 열전달률을 의미하는 뉴셀트 수는 문헌치와 비교할 때 뉴톤 유체 영역과 멱법칙 영역에서 각각 0.025% 및 0.14% 내에서 일치함을 보였다. 비뉴톤 확장 멱법칙 유체 모델의 형태를 띠는 shear-thickening 유체를 열교환기 또는 상용파이프 내의 사각형 단면 파이프 내에서 사용하면 유동지수(n)에 따라서 뉴톤 유체보다 최대 160%의 압력강하를 증가시켰고 최대 14%의 대류 열전달 감소를 발생시킬 수 있었다.

본 연구는 시간압력이 주어진 상황에서 개인의 고유한 인지특성인 인지양식과 과제의 난이도에 따른 학습맥락이 시각변별과제의 기술습득과 전이에 어떠한 영향을 주는지 알아보고자 하였다. 자극은 다각형 비교과제를 이용하였으며, 실험은 스크린 세션, 훈련 세션 그리고 전이 세션으로 구성되었다. 스크린 세션에서는 참가자를 인지양식(분석적-전체적)에 따라 구분하였으며, 훈련 세션에서는 학습맥락의 구분을 위해 과제의 난이도를 어려운 조건과 쉬운 조건으로 나누었다. 전이 세션에서는 모든 피험자가 새로운 난이도의 다각형을 비교하였다. 훈련 세션과 전이 세션에서는 시간압력의 효과를 보기 위해, 1.5초가 지나면 자극이 사라지게 하였다. 전 세션에 걸쳐 정확도와 반응시간을 측정하였다 실험결과, 분석적 처리자는 훈련 세션 동안 전체적 처리자와 같은 수준의 빠른 반응을 보이나, 훈련이 지속될수록 반응시간의 기울기가 증가하였다. 이러한 결과는 분석적 처리자가 자극의 세부특징들을 일 대 일로 비교하는 원래의 처리스타일로 회귀했음을 의미한다. 반면, 분석적 처리를 유도하는 어려운 학습맥락에서 훈련한 전체적 처리자의 경우, 전이 세션의 초기블록에서 반응시간의 증가를 보였다. 이것은 전체적 처리자가 어려운 학습맥락에 의해 분석적 전략을 개발했다는 것을 의미한다. 이러한 결과들을 통해 시간압력 상황에서도 개인의 인지양식의 차이가 인지전략의 개발 및 기술습득에 영향을 미치는 것을 확인할 수 있다.

Heat transfer performance improvement by fin and groovs is studied for condensation of R-11 on integral-fin tubes. Eight tubes with trapczodially shaped integral-fins having fin density from 748 to 1654fpm(fin per meter) and 10, 30 grooves are tested. A plain tube having the same diameter as the finned tubes is also used for comparison. R-11 condensates at saturation state of 32 ℃ on the outside tube surface coded by inside water flow. All of test data are taken at steady state. The heat transfer loop is used for testing singe long tubes and cooling is pumped from a storage tank through filters and folwmeters to the horizontal test section where it is heated by steam condensing on the outside of the tubes. The pressure drop across the test section is measured by menas pressure gauge and manometer. The results obtained in this study is as follows : 1. Based on inside diameter and nominal inside area, overall heat transfer coefficients of finned tube are enhanced up to 1.6 ~ 3.7 times that of a plain tube at a constant Reynolds number. 2. Friction factors are up to 1.6 ~ 2.1 times those of plain tubes. 3. The constant pumping power ratio for the low integral-fin tubes increase directly with the effective area to the nominal area ratio, and with the effective area diameter ratio. 4. A tube having a fin density of 1299fpm and 30 grooves has the best heat transfer performance.

The hollowed precast concrete (PC) column supports beams during construction so that local compression acts on the column. At that time, the stress distribution from the beams to the column varies if hollow size varies. After the hollow is filled with grout concrete, the column has two layer, outer and inner elements with different compressive strength each other. Therefore, hollow size affect axial capacity of column after filling the hollow. Based on the above background, this paper performed a finite element (FE) analysis with parameter of hollow size to find the stress distribution of hollowed PC column during construction as well as after construction. As an analysis result, the wider the hollow size is, the less local compress strength is during construction. Also, the axial compressive resistance of column decreased when the hollow size is wider.

When performing steering by an autopilot (automatic steering gear), a sensitivity adjustment is mainly determined by P value and D value. These values differ in the optimal combination by model of ship and external forces. This research was carried out simulation case studies and examined movement of Pure Car Carrier, which easily received ship by wind pressure influence in low speed We investigated the relation of horizontal migration(transfer) of ship's body and P-D value. Based on it, four parameters of P-D at approaching berth could be suggested Hence there were suggestions of parameters; Distance to maximum lee point, Time to maximum lee point, Time to return to original course and Time to 300th second. The correlation of these parameters and P-D value were also considered. As a result, we think that this index, like formulated P-D, leads to an easy and safe navigation by utilizing these indices.