• Proceedings of the Korean Vacuum Society Conference
• /
• 2015.08a
• /
• pp.98.1-98.1
• /
• 2015

G-M극저온냉동기의 구동으로 인해 발생되는 크라이오 펌프의 진동 저감을 위해 각 요소에 해당하는 부품의 소재 및 모델 변경으로 설계에 반영하고자 한다. G-M극저온냉동기는 헬륨냉매를 사용하여 2개의 정압과정과 2개의 정적과정으로 구성되는 냉동사이클을 구성하는데, 구조적 특성상 내부 왕복기의 운동과 고저압변환에 따른 압력차이가 냉동기의 진동을 유발하므로 진공성능에 영향을 줄 수 있으므로, 이를 최소화하는 기술 개발이 필요하다. 헬륨냉매의 고압 유동에 따른 관로 압력증가로 인한 유동소음이 발생하는데, 이로 인한 소음을 줄이기 위해 관로의 최적화 설계/방진구조반영(DAMPER)으로 진동 안정화(Vibration Stabilization)설계를 수행 하고자 하며, 이에 따른 최적화 연구을 수행하고자 한다. 일차적으로, 기존 시스템의 진동측정을 통해 진동의 가진원을 밝히고 진동 전달경로를 파악하고자한다. 진동 가진원의 가진 최소화, 진동전달경로의 전달률 최소화, 고압유동에 따른 관로 설계 최적화를 진동해석, 탄성체 동역학해석, 그리고 유동해석을 통해 진동 및 소음의 최소화 방안을 도출하고자 한다. 해석결과를 토대로 진동가진원의 최소화를 위한 제품설계변경과 진동전달경로에 대한 방진을 위한 dmper 적용(전달률 최소화) 및 유동소음 최소화를 위한 damper나 관로 최적화 설계를 수행한다. 상기 기존시스템 측정/분석, CAE해석을 통한 진동/소음의 최적화방안도출 및 실제품 적용기술은 저진동 크라이오펌프 개발을 위한 기반 기술 확립에 크게 기여할것이며, 향후 크라이오펌프 고도화 및 최신 기술 제품 개발에 큰 기여가 기대된다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.41 no.2
• /
• pp.135-143
• /
• 2017

A customized CFD simulator to perform thermo-fluid dynamic simulations of an HVAC for an indoor space is presented. This simulation system has been developed for engineers studying architectural engineering, as the HVAC mechanical systems used in housings and buildings. Hence, all functions and options are so designed to be suitable that they are suitable for non-CFD experts as well as CFD engineers. A Computational mesh is generated by open-source libraries, FEMM (Finite Element Method Magnetics), and OpenFOAM. Once the boundary conditions are set, the fluid dynamic calculations are performed using the OpenFOAM solver. Numerical results are validated by comparing them with the experimental data for a simple indoor air flow case. In this paper, an entirely new calculation process is introduced, and the flow simulation results for a sample office room are also discussed.

• Journal of Energy Engineering
• /
• v.4 no.2
• /
• pp.261-269
• /
• 1995

본 연구에서는 밀폐형 2상 열사이폰의 액체 Pool에서 발생하는 핵비등현상과 유동영역에 대해 가시화 방법으로 연구하였다. 실험용 열사이폰은 스텐레스와 유리관을 이용하여 제작하였으며, 열공급은 증발부 주위에 설치된 유도 가열용 코일에 고주파를 가함으로써 스텐레스 외면에 발열이 일어나도록 하였다. 이에 따른 결과는 다음과 같다. 실험용 열사이폰은 고주파 가열등 열사이폰의 작동성능을 저해하는 여러 요인들이 포함되어 있었으나, 실험결과 이러한 문제는 실험 내용에 영향을 미칠만큼 크게 나타나지 않았다. 열속과 상당압력의 범위는 각각2$m^2$, 0.1

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2002.11a
• /
• pp.417-418
• /
• 2002

열분해는 독성이 강한 염화탄화수소의 처리뿐만 아니라 염화물을 효과적으로 제거하여 이들로부터 유용한 탄화수소를 얻을 수 있는 반응이다 Biomass에 열분해를 적용하여 가스상, 액상, 고상형태의 유동한 부산물로 전환시키고 있으며 현재 액상생성물은 외국에서 큰 주목을 받고 있는 부산물이다. 1,1,2-trichloroethane(TCE)는 독성이 강한 휘발성 유기화합물(VOC)이며 발암물질이다. (중략)

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.19 no.2
• /
• pp.111-119
• /
• 2016

Gas-Liquid multiphase flow simulation has been carried out using the Lattice boltzmann method. For the interface treatment, pseudo-potential model (Shan-Chen) was used with the Carnahan-Starling equation of state. Exact Difference Method also applied for the treatment of the force term. Through the developed code, we simulated coexsitence structure of high and low density, phase separation, surface tension effect, characteristics of moving interface, homogeneous and heterogeneous cavitation and bubble collaps.

• Journal of Advanced Marine Engineering and Technology
• /
• v.38 no.7
• /
• pp.821-827
• /
• 2014

In this study, an experimental study was performed to predict the two-phase frictional pressure drop of FC-72 in parallel micro-channels. The parallel micro-channels consist of 15 channels with depth 0.2 mm, width 0.45 mm and length 60 mm. And tests were performed in the ranges of mass fluxes from 152.2 to $584.2kg/m^2s$ and heat fluxes from 7.5 to $28.3kW/m^2$. The experimental data was compared and analyzed with existing correlations to predict the pressure drop. The existing methods to predict the pressure drop used the homogeneous model and the separated model. In this study, the new correlation was proposed by modified existing correlation using the separated model, and the new correlation predicted consequently with the experimental data within MAE of 9.6%.

• Journal of Korean Society of Neurocognitive Rehabilitation
• /
• v.10 no.2
• /
• pp.19-26
• /
• 2018

Many people do not realize that they have poor neck posture. Incorrect forward head posture can lead to turtle neck. This aim to development of specific chair to reduce tension and other symptoms of turtle neck posture. This turtle neck syndrome adjusting chair is a chair that supports the hip and shin of a person to help them correct their posture. It is consisted of the shin support that supports the shin in an angle and the hip support that supports one's hip while the shin is supported at an angle, the main frame that has the two of them connected and the fluid seat that is joined at the top of the hip support and reacts accordingly to the shape of the hip. This is a posture correction chair which has the fluid seat that provides unstable hip support so that it can allow a person to realize their posture from the constant stimulation about the posture. When one seats on the posture correction chair, their hip and shin are supported at an angle that straitens their back, and as their back is straightened, their shoulders and chest are opened, and the neck is positioned at the middle to help them correct their posture. An unbalanced posture causes discomfort to the person seated at the chair, and the person sitting on the posture correction chair will continuously adjust his/her posture to balance the hips to keep the correct posture. Through this process, the person shall adjust his/her left and right posture, ultimately increasing the effectiveness of posture correction. A future collective study on the continuous posture correction of people having turtle neck syndrome using this posture correction chair is required.

• Journal of the Korean Institute of Gas
• /
• v.25 no.4
• /
• pp.10-18
• /
• 2021

CO₂ storage technology in an aquifer is one of the most effective way to decrease global warming due to a high storage capacity and economics. A demonstration-scale offshore CO₂ storage project was performed in a geological deep aquifer in the Pohang Basin, Korea for a technological development of large-scale CO₂ storage. A challenging issue in the early design stage of the project was to establish the proper injectivity during CO₂ injection. To solve this issue, injection conditions were calculated by calculating injection rate, pressure, temperature, CO₂ phase change, and thermodynamic properties. For this study, we simulated and numerically analyzed CO₂ phase change from gas to supercritical phase and flow behavior in transport piping and injection tubing using OLGA program. Our results provide the injectivity conditions of CO₂ injection system combined with a bottomhole pressure of an aquifer.

• 한국가스학회:학술대회논문집
• /
• 1998.09a
• /
• pp.153-161
• /
• 1998

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.15 no.3
• /
• pp.982-991
• /
• 1991

본 연구에서는 냉방기에서 널리 이용되고 있는 평판핀이 연속적으로 부착된 다관식 증발 열교환기에 대하여 (1) 냉매의 열역학적 물성치의 변화 (2) 냉매와 공기 측 열전달 계수의 변화 (3) 냉매측 관 마찰 손실등을 고려한 시뮬레이션 프로그램을 작성하고 그 결과를 실험을 통하여 보정 완성하였다. 계산결과로 부터 공조기기의 설계조건, 공조계통 해석을 위한 기초자료를 제시하였다.