• 대한기계학회논문집A
• /
• 제25권7호
• /
• pp.1031-1038
• /
• 2001

In order to verify the analytical methods predicting failure behavior of cracked piping, full-scale pipe tests are crucial in nuclear power plant piping. For this reason, series of international test programs have been conducted. However, full-scale pipe tests require expensive testing equipment and long period of testing time. The objective of this paper is to develop a test system which can economically simulate the full-scale pipe test regarding the integrity evaluation. This system provides the failure behavior of cracked pipe by testing a wide-plate specimen. The system provides the failure behavior of cracked pipe by testing a wide-plate specimen. The system was developed for the integrity evaluation of nuclear piping based on the methodology of hardware-in-the-loop (HiL) simulation. Using this simulator, the piping integrity can be evaluated based on the elastic-plastic behavior of full-scale pipe, and the high cost full-scale pipe test may be replaced with this economical system.

• Nuclear Engineering and Technology
• /
• 제50권4호
• /
• pp.582-588
• /
• 2018

Accident diagnosis is one of the complex tasks for nuclear power plant (NPP) operators. In abnormal or emergency situations, the diagnostic activity of the NPP states is burdensome though necessary. Numerous computer-based methods and operator support systems have been suggested to address this problem. Among them, the recurrent neural network (RNN) has performed well at analyzing time series data. This study proposes an algorithm for accident diagnosis using long short-term memory (LSTM), which is a kind of RNN, which improves the limitation for time reflection. The algorithm consists of preprocessing, the LSTM network, and postprocessing. In the LSTM-based algorithm, preprocessed input variables are calculated to output the accident diagnosis results. The outputs are also postprocessed using softmax to determine the ranking of accident diagnosis results with probabilities. This algorithm was trained using a compact nuclear simulator for several accidents: a loss of coolant accident, a steam generator tube rupture, and a main steam line break. The trained algorithm was also tested to demonstrate the feasibility of diagnosing NPP accidents.

• 산업경영시스템학회지
• /
• 제33권1호
• /
• pp.108-113
• /
• 2010

The purpose of this study was to investigate the differences of driving performance and physiological responses between young male and female drivers for unexpected situation using a graphic vehicle simulator. The participants included 20 college graduates; 23 males aged $24.3\;{\pm}\;1.4$ with $2.3\;{\pm}\;1.5$ years of driving experiences and 23 females aged $23.2\;{\pm}\;2.1$ with $2.2\;{\pm}\;1.7$ years of driving experience. The participants were instructed to drive the vehicle simulator which was programed unexpected situation for two minutes. The physiological measurements used were autonomic responses of electrocardiogram (ECG) and skin conductance response (SCR), and the driving performance measurements used were the reaction time of break and the rate of collision for unexpected situation. Results showed that there were no significant differences between male and female drivers in the reaction time of break and the rate of collision for unexpected situation. Averaged R-R interval decreased and LF IHF and SCL amplitude increased for unexpected situation. There were no significant differences between male and female in the averaged R-R interval and LF/HF for unexpected situation. On the other hand, SCL amplitude of female was higher than male. Rising time to maximum SCL amplitude of female was longer than male.

• The Journal of Korean Physical Therapy
• /
• 제30권5호
• /
• pp.187-192
• /
• 2018

Purpose: This study compared the functional fitness and brake response of elderly and young drivers to confirm the correlation between the functional fitness and brake response. Methods: This study was a cross sectional observational design. Older drivers (>65age, n=21) and young adult drivers (20-40aged, n=20) were enrolled as subjects. The functional fitness of the subjects was measured using a senior fitness test consisting of a back scratch (BS), chair sit and reach (CSR), arm curl (AC), chair stand up (CSU), foot up and go (8-FUG), and 2-minute step (2-MS). The brake response used the virtual driving simulator to measure the brake reaction time (BRT) and braking distance (BD) according to the pedestrian protection and traffic signal compliance. Results: The older drivers had a lower BS (p<0.000), CSU (p=0.040), and 8-FUG (p=0.011) than the young adult drivers. BS and 8-FUG showed a significant positive correlation with the BRT and BD of pedestrian protection and traffic signal compliance. CSU showed a significant negative correlation with the BRT of pedestrian protection and traffic signal compliance. Conclusion: These findings suggest that the flexibility of the upper extremity, lower extremity strength, and agility are strongly correlated with the driving performance of elderly drivers.

• 물과 미래
• /
• 제29권3호
• /
• pp.197-205
• /
• 1996

상수도 관망시설에서 각 관로는 시간이 경과함에 따라 각종 부식이 일어나 통수능이 저하된다. 그러므로 적절한 시기에 갱생이나 교체 등의 처리를 해주어야 한다. 본는 연구에서는 각 수요절점에서 요구수량, 요구압력 등 수리학적 조건을 만족시켜주며 동시에 최소의 비용으로 노구된 관로를 처리해주는 의사결정모형을 개발하였다. 교체비용, 관파열보수비용, 양수비용, 관 파열율, 연이율 등은 각 관로의 교체시기를 경제적으로 결정하는데 이용된다. 그리고 배수시설의 수리학적 만족여부는 관망계산 프로그램 KYPIPE에 의해 점검된다. 시스템이 수리학적 조건을 만족지 못할 경우 교체시기는 조건이 만족될 때까지 앞당겨진다. 본 모형은 기존 송배수시설인 수도권 광역상수도 제1단계에 적용되었다. 모형을 이용해 산출한 최적교체시키는 수리학적으로 모의해본 결과 문제가 없으며를 알 수 있었다.

• 한국통신학회논문지
• /
• 제31권11A호
• /
• pp.1059-1067
• /
• 2006

AODV(Ad-hoc On-Demand Distance Vector) 라우팅 프로토콜은 Ad-hoc 네트워크에서 이동 노드를 사용할 수 있도록 제안된 라우팅 프로토콜이다. AODV 라우팅 프로토콜을 사용하는 Ad-hoc 네트워크에서 고속으로 이동하는 노드가 포함되어 있는 경우 항상 최적 경로를 확보할 수 없는 문제로 인하여 경로 단절과 전송 지연이 발생한다 따라서 본 논문에서는 고속으로 변화하는 네트워크의 토폴로지에서 항상 최적의 경로를 확보 할 수 있는 메커니즘을 통하여 경로의 단절과 전송 지연을 최소화할 수 있는 AODV를 기반으로 하는 라우팅 프로토콜을 제안하였으며 ns2 시뮬레이터를 이용하여 제안 프로토콜을 평가하였다. Ad-hoc 네트워크를 위한 여러 가지 기반 기술의 검증을 위하여 실제의 Ad-hoc 네트워크 테스트 베드를 구현하였다. 본 논문에서는 AODV 라우팅 프로토콜, NAT, Netfilter등의 Ad-hoc을 위한 소프트웨어 검증을 위한 많은 이벤트 메시지를 성능 저하 없이 동작시킬 수 있는 고성능의 임베디드 시스템을 설계 개발하였다. 개발된 하드웨어를 이용한 Ad-hoc 네트워크 테스트 베드에서 AODV 라우팅 프로토콜의 정상 동작과 기존 인터넷 망과의 연동을 확인하였다.

• 한국전기전자재료학회논문지
• /
• 제30권6호
• /
• pp.345-348
• /
• 2017

In this work, static characteristics of 4H-SiC SJ-ACCUFETs were obtained by adjusting the p-pillar region. The structure of this SJ-ACCUFET was designed by using a two-dimensional simulator. The static characteristics of SJ-ACCUFET, such as the breakdown voltages, on-resistance, and figure of merits, were obtained by varying the p-pillar doping concentration from $1{\times}10^{15}cm^{-3}$ to $5{\times}10^{16}cm^{-3}$ and the thickness from $0{\mu}m$ to $9{\mu}m$. The doping concentration and the thickness of p-pillar region are closely related to the break down voltage and on-resistance and threshold voltages. Hence a silicon carbide SJ-ACCUFET structure with highly intensified breakdown voltages and low on-resistances with good figure of merits can be achieved by optimizing the p-pillar thickness and doping concentration.

• 대한인간공학회지
• /
• 제36권4호
• /
• pp.293-303
• /
• 2017

Objective: This study aims to evaluate visual discomfort and visual fatigue caused by watching HMD and smartphones by conducting both subjective and objective measure. Background: With the rapid development of mobile Head-Mounted Display (HMD), the problem of visual discomfort and visual fatigue caused by watching Virtual Reality (VR) contents became a crucial concern for consumers and manufacturers, especially given that the casing of mobile HMD keeps the phone at a specified distance from the lenses that is close to the eyes. Method: Two smartphones were chosen for a preliminary study: LG G5 and Galaxy S7. As for a main study, iPhone 6S and Galaxy S7 were used. After being exposed to the selected clips, participants were asked to answer Simulator Sickness Questionnaire (SSQ) and went through optometric tests that measure tear break-up time, spherical equivalent, and contrast sensitivity. Results: The subjective assessments indicate that HMD causes more visual discomfort compared to watching a smartphone. Furthermore, the experimental result confirms that watching a HMD causes more eye dryness compared to smartphones. Conclusion: The result of the study compared visual discomfort and visual fatigue of two different displays, HMD and smartphone, and confirmed that watching HMD causes more visual discomfort and visual fatigue. Application: Ultimately, this study could help manufacturers understand the strengths and weaknesses of different display forms, providing guidance for an effective application of HMD.

• 전기전자학회논문지
• /
• 제20권2호
• /
• pp.163-166
• /
• 2016

It is important to operate the driving circuit under the optimal condition through precisely sensing the power consumption causing the temperature made mainly by the MOSFET (metal-oxide semiconductor field-effect transistor) when a BLDC (Brushless Direct Current) motor operates. In this letter, a Super-junction (SJ) power TMOSFET (trench metal-oxide semiconductor field-effect transistor) with an ultra-low specific on-resistance of $0.96m{\Omega}{\cdot}cm^2$ under the same break down voltage of 100 V is designed by using of the SILVACO TCAD 2D device simulator, Atlas, while the specific on-resistance of the traditional power MOSFET has tens of $m{\Omega}{\cdot}cm^2$, which makes the higher power consumption. The SPICE simulation for measuring the power distribution of 25 cells for a chip is carried out, in which a unit cell is a SJ Power TMOSFET with resistor arrays. In addition, the power consumption for each unit cell of SJ Power TMOSFET, considering the number, pattern and position of bonding, is computed and the power distribution for an ANSYS model is obtained, and the SJ Power TMOSFET is designed to make the power of the chip distributed uniformly to guarantee it's reliability.

• 한국연소학회지
• /
• 제13권2호
• /
• pp.23-32
• /
• 2008

Gasification characteristics in the fluidized bed reactor are essential for the design of a gasification furnace to optimize the operation condition. Moisture content of the solid fuel is one of the important factors to influence directly the gasification characteristics. So it is necessary to investigate the effect of moisture content of solid fuel in partial oxidation condition. Gasification characteristics are investigated with results from thermogravimetric analyzer and lab-scale fluidized bed reactor for wood and RDF samples along with changing moisture contents. Additionally lab-scale fluidized bed reactor was run continuously and gas concentrations at the exit were measured. It is observed that the rate of reaction in partial oxidation condition is between the results from the combustion environment and from the inert condition. Moisture content in a particle slows down the heating rate of a particle. So, reaction is delayed by the moisture content. However, RDF samples those are easy to break-up don't show the effect of moisture content. The result of continuous operation condition shows that proper moisture content promotes gasification because steam from the particles helps gasification of the solid fuel. A simulation to predict the syn-gas composition was conducted by the Aspen Plus process simulator. The cold gas efficiency of the experiment was compared with results from the simulation.