• Nuclear Engineering and Technology
• /
• 제50권8호
• /
• pp.1412-1420
• /
• 2018

An experiment was performed using the large-scale test facility (LSTF), which simulated a 1% vessel upper head small-break loss-of-coolant accident with an accident management (AM) measure under an assumption of total-failure of high-pressure injection (HPI) system in a pressurized water reactor (PWR). In the LSTF test, liquid level in the upper head affected break flow rate. Coolant was manually injected from the HPI system into cold legs as the AM measure when the maximum core exit temperature reached 623 K. The cladding surface temperature largely increased due to late and slow response of the core exit thermocouples. The AM measure was confirmed to be effective for the core cooling. The RELAP5/MOD3.3 code indicated insufficient prediction of primary coolant distribution. The author conducted uncertainty analysis for the LSTF test employing created phenomena identification and ranking table for each component. The author clarified that peak cladding temperature was largely dependent on the combination of multiple uncertain parameters within the defined uncertain ranges.

• 한국인터넷방송통신학회논문지
• /
• 제24권4호
• /
• pp.195-200
• /
• 2024

도시화와 자동차 수요의 증가로 인해 도시 주차 문제가 심각한 사회적 문제로 대두되고 있다. 이에 따라 주차장 상황을 파악하고 운전자에게 효율적인 주차 정보를 제공하기 위해 주차장의 입출차 데이터를 활용한 연구를 진행하였다. 본 논문은 공공데이터 기반 입출차 데이터를 전처리하여 주차시간을 추출하고, 최빈값을 활용하여 예상 출차시간을 제공함으로써 운전자가 주차하고자 하는 시간에 차량이 빠져나갈 것을 파악할 수 있었다. 향후 연구에서는 실시간 주차 관제시스템을 이용하여 현재의 시스템을 개선하고, 주차 공간 파악의 정확성과 효율성을 향상시키려고 한다.

• 한국정밀공학회지
• /
• 제20권12호
• /
• pp.25-33
• /
• 2003

A burr has been defined as undesirable projection of material formed as a result of plastic flow from a cutting or shearing operation. It is unavoidable in all kinds of machining operation. As a result, burr makes troubles on manufacturing process due to deburring cost, quality of products and productivity. In this study, the primary interest is about exit burr. The burr formation mechanism in each type of burr is classified. Data bases are developed to predict burr formation result. In the milling operation, we develop an algorithm to analyze the burr formation mechanism by the geometrical analysis on the multi featured workpiece with multi cutting path. The algorithm includes three steps, i. e., the feature identification, the cutting condition identification, and the analysis on exit burr formation. We can predict which portion of workpiece would have the exit burr in advance so that we can manage to find a way to minimize the exit burr formation in an actual cutting. Also, this algorithm can be implemented in a commercial CAM package so that we can simulate the NC code to review the burr formation in advance.

• 한국통신학회논문지
• /
• 제35권7C호
• /
• pp.587-593
• /
• 2010

본 논문에서는 extrinsic information transfer (EXIT) chart를 이용하여 다중 안테나 시스템에서 irregular low-density parity-check (LDPC) code를 설계하는 방법을 기술한다. 다중 안테나 기반의 Irregular LDPC code 설계를 위하여 maximum a posteriori probability (MAP) 방식의 다중 안테나 검출 방식이 사용되었으며 수신기는 다중 안테나 검출기와 LDPC 복호기 사이에서 복호된 soft 정보를 주고 받는 turbo iterative 구조를 가정하였다. 다중 안테나 기반의 irregular LDPC code의 edge degree 분포는 EXIT chart와 linear optimization programming 기법을 사용하여 얻을 수 있으며 컴퓨터 시뮬레이션을 통하여 제안된 방법으로 설계된 irregular LDPC code의 성능을 다양한 환경에서 검증하였다.

• 대한조선학회논문집
• /
• 제36권4호
• /
• pp.37-47
• /
• 1999

본 논문에서는 접수(water entry) 및 이수(water exit) 문제를 유동장의 지배방정식인 2차원 비압축성 Navier-Stokes방정식을 일반좌표계(generalized coordinate system)에서 유한체적법(Finite Volume Method)으로 이산화 하여 해석하였다. 강체의 접수 또는 이수 상황에서 발생하는 자유수면 변형에 대한 처리는 Level-Set[11]기법을 사용하였다. 수치계산결과에서 접수에 대한 유체충격력에 대한 계산결과는 쐐기(wedge)형과 flared-ship 단면의 실험결과[5]와 비교하였으며, 원형실린더의 이수문제에서는 시간에 따른 자유수면의 변형 및 유동장의 특징을 살펴보았다.

• 설비공학논문집
• /
• 제26권12호
• /
• pp.553-558
• /
• 2014

Geothermal energy can be used with a geothermal heat pump or an earth-to-air heat exchange system (EAHES), which is referred to as a "cooling tube" in Korea. In this study, we suggest EAHES burial guidelines in terms of the parameters of buried pipe length and air velocity regarding the exit air temperature of EAHES. The exit air temperature for EAHES in three regions (Changwon, Busan and Seoul) was calculated with variation in buried pipe length and air velocity at ${\Phi}100mm$ and ${\Phi}200mm$. In conclusion, variation in the buried pipe length is more effective than that of air velocity to achieve the required exit air temperature.

• Journal of Positioning, Navigation, and Timing
• /
• 제2권1호
• /
• pp.91-100
• /
• 2013

This paper introduces an indoor sensor fusion wireless communication device which provides the Location Based Service (LBS) using fire prevention facility. The proposed system can provide information in real time by optimizing the hardware of Wi-Fi technology. The proposed system can be applied to a fire prevention facility (i.e., emergency exit) and provide information such as escape way, emergency exit location, and accident alarm to smart phone users, dedicated terminal holders, or other related organizations including guardians, which makes them respond instantly with lifesaving, emergency mobilization, etc. Also, the proposed system can be used as a composite fire detection sensor node with additional fire and motion detect sensors.

• 한국콘텐츠학회논문지
• /
• 제16권9호
• /
• pp.12-21
• /
• 2016

본 논문에서는 긴급 재해 발생 시 피난 지원을 목적으로 하는 긴급피난지원시스템을 구축하기 위하여 실내에서 화재, 테러 등의 재해 발생 시 탈출 경로 탐색 알고리즘을 구현하였다. 긴급 상황이 발생하면 알고리즘은 가장 빨리 탈출할 수 있는 비상구로 탈출 경로를 안내해 준다. 알고리즘은 비상구나 비상구 이외의 지역의 인구 밀도와 연령별 가중치를 적용하여 탈출 경로를 계산한다. 본 시스템은 혼잡한 비상구를 우회하게 함으로써 비상구의 과중한 혼잡과 탈출 경로 상의 혼잡을 감소시키면서 재해 발생 지역을 우회하여 탈출하도록 돕는다.

• 태양에너지
• /
• 제20권1호
• /
• pp.97-108
• /
• 2000

The purpose of this study is to minimize the heat transfer surface area and cold fluid exit temperature of heat exchanger which applied to the refrigeration and air-conditioning system by utilizing the thermoelectric principle. Both uniform and non-uniform current distribution methods which applied to the analysis of the TE elements that incorporates heat exchanger were investigated. The non-uniform current distribution method had the better coefficient of performance and had the lower cold fluid exit temperature of the TE cooling system than the uniform current distribution method. It was found that if a TE cooling system incorporates a heat exchanger, a non-uniform current distribution should guarantee to the lowest cold fluid exit temperature. Also, the hybrid method (combination of the uniform and non-uniform current distribution method) is investigated to achieve the best results by combining the uniform and non-uniform current distributions. The results show that it can lower the cold fluid exit temperature and reduce the heat transfer surface area for the parallel flow arrangement if we apply the constant current in some entry region and the non-uniform increasing current in the direction of the cold fluid flow afterwards.

• International journal of advanced smart convergence
• /
• 제6권1호
• /
• pp.76-81
• /
• 2017

This paper presents a low cost and flexible IoT enabled smart LED controller using Arduino that is used for emergency exit signs. The Internet of Things (IoT) is become a global network that put together physical objects using network communications for the purpose of inter-communication of devices, access information on internet, interaction with users as well as permanent connected environment. A crucial point in this paper, is underlined on the potential key points of applying the Arduino platform as low cost, easy to use microcontroller with combination of various sensors applied in IoT technology to facilitate and establishment of intelligent products. To demonstrate the feasibility and effectiveness of the system, devices such as LED strip, combination of various sensors, Arduino, power plug and ZigBee module have been integrated to setup smart emergency exit sign system. The general concept of the proposed system design discussed in this paper is all about the combination of various sensor such as smoke detector sensor, humidity, temperature sensor, glass break sensors as well as camera sensor that are connected to the main controller (Arduino) for the purpose of communicating with LED exit signs displayer and dedicated PC monitors from integrated system monitoring (controller room) through gateway devices using Zig bee module. A critical appraisal of the approach in the area concludes the paper.