• 한국시뮬레이션학회:학술대회논문집
• /
• 한국시뮬레이션학회 2000년도 추계학술대회 논문집
• /
• pp.61-66
• /
• 2000

전력연구원에서 개량중인 한국원자력교육원 제 2호기 (KNPEC#2) 시뮬레이터의 검증을 위해 출력 연속변화 등 시나리오를 선정하여, 이에 대한 기준 데이터를 최적평가용 전산코드인 RETRAN과 MARS를 이용하여 생산하였다. 선정된 시나리오를 정확히 모사하기 위해 KNPEC#2 시뮬레이터의 대상호기인 영광 1,2호기 노심냉각계통 및 증기 계통을 상세 분할하였으며, 주요 기기 및 제어 계통을 모델링하였다. 모델링을 위해서 발전소 실제 운전자료를 활용하였으며, 필요시 설계자료와 유사호기인 고리 3,4호기 자료를 참고하였다. 끝으로 정상상태 및 비정상상태 운전조건과의 비교를 통해 모델링의 타당성을 확인한 후 각 시나리오에 따른 데이터를 생성하였다.

• Journal of Acupuncture Research
• /
• 제27권5호
• /
• pp.51-58
• /
• 2010

Objectives : The purpose of this study is to assess the effect of laser acupuncture at $HT_7$ for reducing mental stress using power spectrum analysis of the heart rate variability. Methods : 36 healthy volunteers(control group: 18, treatment group: 18) participated in this study. After instrumentation and 5-minute rest period, 5-minute metal stress by operation was provided. HRV was recorded before and after the mental stress(1st, 2nd HRV). After 2nd HRV recording, the control group rested for 15 minutes without any treatments. Participants in the treatment group received laser acupuncture to $HT_7$ unilaterally and rested for 15minutes. Points were irradiated for 60seconds, and the intensity was 1.8J(output 20%). And then 3rd HRV was recorded. Results : In simple rest group, LF norm showed a significant change after mental stress. In laser acupuncture group, LF norm, HF norm, LF, HF and LF/HF ratio showed a significant change after mental stress. But there were no significant difference between two groups(ANCOVA test, p>0.05). In laser acupuncture group, LF norm, HF norm, HF and LF/HF ratio showed a significant change after laser acupuncture treatment. And there were significant differences between two groups(p<0.05). Conclusions : This study suggests that laser acupuncture at $HT_7$ can regulate and prevent the alternation of autonomic nervous system due to mental stress.

• 설비공학논문집
• /
• 제24권4호
• /
• pp.297-305
• /
• 2012

In recent large-scale semiconductor manufacturing clean rooms, the energy consumption of outdoor air conditioning systems to heat, humidify, cool and dehumidify incoming outdoor air represents about 45% of the total air conditioning load required to maintain a clean room environment. Therefore, the energy performance evaluation and analysis of outdoor air conditioning systems is useful for reducing the outdoor air conditioning load for a clean room. In the present study, an experiment was conducted to compare the energy consumption of outdoor air conditioning systems with a simple air washer, an exhaust air heat recovery type air washer and a DCC return water heat recovery type air washer. It was shown from the present lab-scale experiment with an outdoor air flow of 1,000 $m^3/h$ that the exhaust air heat recovery type and DCC return water heat recovery type air washer outdoor air conditioning systems were more energy-efficient for the summer and winter operations than the simple air washer outdoor air conditioning system and furthermore, the DCC return water heat recovery type one was the most energy-efficient in the winter operation.

• 한국산업정보학회논문지
• /
• 제20권4호
• /
• pp.47-54
• /
• 2015

스마트 기술의 확산으로 인하여 개인용 기기와 사무용 기기 가운데 많은 제품들이 스마트 기능을 탑재하고 있다. 이러한 변화는 사용자들의 작업을 원격지에서 시행할 수 있는 시대를 열고 있다. 이에 본 연구에서는 우리 주변에서 쉽게 찾아볼 수 있는 멀티 플러그에 스마트 기능을 추가하여 언제 어디서든 무선 네트워크 기술을 통하여 가정에 설치된 멀티 플러그를 조작할 수 있도록 하는 스마트 멀티 플러그 시스템을 설계하고 구현함으로써 기존의 멀티 플러그가 갖는 한계를 보완하고자 한다. 본 논문에서 제안하는 스마트 멀티 플러그는 스마트 기기에서 원격으로 언제 어디서든 플러그를 조작함으로써 노약자나 어린이 등 스스로 전원장치의 작동이 어려운 사용자에게 필요한 서비스를 제공할 수 있으며 u-Farming, 테라리움, 스마트 홈 등 원격으로 전원장치의 관리가 필요한 분야에서 폭넓게 사용될 것으로 기대된다.

• International Journal of Automotive Technology
• /
• 제7권1호
• /
• pp.1-7
• /
• 2006

The ignition delay of a dual fuel system has been numerically investigated by adopting a constant volume chamber as a model problem simulating diesel engine relevant conditions. A detailed chemical kinetic mechanism, consisting of 28 species and 135 elementary reactions, of dimethyl ether (DME) with methane ($CH_{4}$) sub-mechanism has been used in conjunction with the multi-dimensional reactive flow KIVA-3V code to simulate the autoignition process. The start of ignition was defined as the moment when the maximum temperature in the combustion vessel reached to 1900 K with which a best agreement with existing experiment was achieved. Ignition delays of liquid DME injected into air at various high pressures and temperatures compared well with the existing experimental results in a combustion bomb. When a small quantity of liquid DME was injected into premixtures of $CH_{4}$/air, the ignition delay times of the dual fuel system are longer than that observed with DME only, especially at higher initial temperatures. The variation in the ignition delay between DME only and dual fuel case tend to be constant for lower initial temperatures. It was also found that the predicted values of the ignition delay in dual fuel operation are dependent on the concentration of the gaseous $CH_{4}$ in the chamber charge and less dependent on the injected mass of DME. Temperature and equivalence ratio contours of the combustion process showed that the ignition commonly starts in the boundary at which near stoichiometric mixtures could exists. Parametric studies are also conducted to show the effect of additive such as hydrogen peroxide in the ignition delay. Apart from accurate predictions of ignition delay, the coupling between multi-dimensional flow and multi-step chemistry is essential to reveal detailed features of the ignition process.

• 한국수소및신에너지학회논문집
• /
• 제24권1호
• /
• pp.12-19
• /
• 2013

A gasification process with pre-combustion $CO_2$ capture process, which converts coal into environment-friendly synthetic gas, might be promising option for sustainable energy conversion. In the coal gasification for power generation, coal is converted into $H_2$, CO and $CO_2$. To reduce the cost of $CO_2$ capture and to maximize hydrogen production, the removal of CO and the additional production of hydrogen might be needed. In this study, a 2l/min water gas shift system for a coal gasifier has been studied. To control the concentration of major components such as $H_2$, CO, and $CO_2$, MFCs were used in experimental apparatus. The gas concentration in these experiments was equal with syngas concentration from dry coal gasifiers ($H_2$: 25-35, CO: 60-65, $CO_2$: 5-15 vol%). The operation conditions of the WGS system were $200-400^{\circ}C$, 1-10bar. Steam/Carbon ratios were between 2.0 and 5.0. The commercial catalysts were used in the high temperature shift reactor and the low temperature shift reactor. As steam/carbon ratio increased, the conversion (1-$CO_{out}/CO_{in}$) increased from 93% to 97% at the condition of CO: 65, $H_2$: 30, $CO_2$: 5%. However the conversion decreased with increasing of gas flow and temperature. The gas concentration from LTS was $H_2$: 54.7-60.0, $CO_2$: 38.8-44.9, CO: 0.3-1%.

• Journal of Information Processing Systems
• /
• 제14권4호
• /
• pp.989-1009
• /
• 2018

Rapid advances in science and technology with exponential development of smart mobile devices, workstations, supercomputers, smart gadgets and network servers has been witnessed over the past few years. The sudden increase in the Internet population and manifold growth in internet speeds has occasioned the generation of an enormous amount of data, now termed 'big data'. Given this scenario, storage of data on local servers or a personal computer is an issue, which can be resolved by utilizing cloud computing. At present, there are several cloud computing service providers available to resolve the big data issues. This paper establishes a framework that builds Hadoop clusters on the new single-board computer (SBC) Mobile Raspberry Pi. Moreover, these clusters offer facilities for storage as well as computing. Besides the fact that the regular data centers require large amounts of energy for operation, they also need cooling equipment and occupy prime real estate. However, this energy consumption scenario and the physical space constraints can be solved by employing a Mobile Raspberry Pi with Hadoop clusters that provides a cost-effective, low-power, high-speed solution along with micro-data center support for big data. Hadoop provides the required modules for the distributed processing of big data by deploying map-reduce programming approaches. In this work, the performance of SBC clusters and a single computer were compared. It can be observed from the experimental data that the SBC clusters exemplify superior performance to a single computer, by around 20%. Furthermore, the cluster processing speed for large volumes of data can be enhanced by escalating the number of SBC nodes. Data storage is accomplished by using a Hadoop Distributed File System (HDFS), which offers more flexibility and greater scalability than a single computer system.

• 방송공학회논문지
• /
• 제10권3호
• /
• pp.392-400
• /
• 2005

모바일 환경에서의 효과적인 동영상 압축을 위한 고집적 MPEG-4@SP 동영상 압축기인 VideoCore의 구조를 제안한다. 동영상 압축을 수행할 때 움직임 추정, 움직임 보상, 양자화, 이산여현부호화, 가변장부호화와 같은 기능은 외부 메모리 처리가 빈번하기 때문에 높은 메모리 대역폭을 필요로 한다. 본 논문에서 제안한 움직임 추정기는 소용량의 로컬 메모리를 효과적으로 운용함으로써 대용량 외부 메모리와의 메모리 대역폭을 최소화하는 동영상 압축을 가능하게 한다. 또한 제안한 동영상 압축기 구조는 가장 계산량이 많은 움직임 추정부와 이를 제외한 나머지 기능들을 동시에 구동시키는 파이프라인 구조를 채택함으로써 낮은 동작 주파수에서 실시간 고화질 동영상 압축을 실현한다.

• 한국항공우주학회지
• /
• 제37권10호
• /
• pp.1017-1026
• /
• 2009

우주비행체의 주 전력원인 태양전지 시스템은 태양광을 직접 바라본 상태에서 운용되어, 우주의 가혹한 열적/기계적 환경에 직접 노출되므로, 제작/시험 중 발생될 수 있는 미세한 균열, 정전기 및 열 충격 등이 궤도 운용 중 태양전지 시스템의 기능상실로 이어질 가능성을 갖는다. 또한 태양전지 시스템의 전력생성 기본 유닛인 태양전지에 발생된 미세한 균열 또는 열 충격에 따른 태양전지의 내부 파손의 발견을 위해서는 고가의 장비와 복잡한 시험 절차, 그리고 많은 시간을 필요로 하게 된다. 따라서 태양전지 시스템 기능의 건전성을 쉽고, 빠르게 확인하기 위해, 정성적인 태양전지 기능 건전성 평가 방법이 요구된다. 본 논문에서는 요즘 우주비행체에서 가장 많이 사용되는 갈륨-비소 계열의 다접합 태양전지가 갖는 전계발광현상을 이용해 복잡한 반도체 구조를 가지는 태양전지의 기능 건전성을 보다 간단하고 저비용으로 그리고 빠르게 평가하는 방법에 대한 이론적, 기술적 근거를 설명하였다. 또한 이를 실제의 우주용 태양전지 시스템에 적용하기 위한 기술적 사항들과 적용 제한 조건들에 대하여 기술하였다.

• Nuclear Engineering and Technology
• /
• 제41권6호
• /
• pp.785-796
• /
• 2009

A KALIMER-600 concept which is a type of sodium-cooled fast reactor, has been developed at KAERI. It uses sodium as a primary coolant and is a pool-type reactor to enhance safety. Also, a supercritical carbon dioxide ($CO_2$) Brayton cycle is considered as an alternative to an energy conversion system to eliminate the sodium water reaction and to improve efficiency. In this study, a simplified model for analyzing the thermodynamic performance of the KALIMER-600 coupled with a supercritical $CO_2$ Brayton cycle was developed. To develop the analysis model, a commercial modular modeling system (MMS) was adopted as a base engine, which was developed by nHance Technology in USA. It has a convenient graphical user interface and many component modules to model the plant. A new user library for thermodynamic properties of sodium and supercritical $CO_2$ was developed and attached to the MMS. In addition, some component modules in the MMS were modified to be appropriate for analysis of the KALIMER-600 coupled with the supercritical $CO_2$ cycle. Then, a simplified performance analysis code was developed by modeling the KALIMER-600 plant with the modified MMS. After evaluating the developed code with each component data and a steady state of the plant, a simple power reduction and recovery event was evaluated. The results showed an achievable capability for a performance analysis code. The developed code will be used to develop the operational strategy and some control logics for the operation of the KALIMER-600 with a supercritical $CO_2$ Brayton cycle after further studies of analyzing various operational events.