• 설비공학논문집
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• 제26권11호
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• pp.535-540
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• 2014

This paper investigates the exhaust effectiveness of smoke, in the case of fire in a large atrium space. Numerical analysis was conducted to simulate transient fire growth in a test room, modeled by the Murcia atrium fire test. Various indices representing the exhaust performance of the exhaust system were obtained, such as the height of the smoke layer, and the instantaneous and accumulative capture efficiency of the smoke. The residual life time of smoke from the fire was also obtained, by injecting tracer gases at the fire location, depending on the airflow rate, and the location of the exhausts. The capture efficiency based on smoke concentration at the exhausts exhibits how much smoke can be removed by the exhaust system; whereas, the exhaust effectiveness based on residual life time indicates how rapidly the smoke can reach the exhaust locations, before being exhausted. The definitions and meanings of the indices to be used in representing the exhaust performance of a smoke exhaust system installed in a large space are discussed.

• 한국운동역학회지
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• 제28권4호
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• pp.213-218
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• 2018

Objective: The purpose of this study was to examine the effect of the core muscle strength enhancement of the elderly on 8 weeks training using the core exercise equipment for the elderly on the ability to control the whole-body center of mass in posture stabilization. Method: 16 females (10 exercise group, 6 control group) participated in this study. Exercise group took part in the core strength training program for 8 weeks with total of 16 repetitions (2 repetitions per week) using a training device. External perturbation during standing as pulling force applied at the pelvic level in the anterior direction was provided to the subject. In a UCM model, the controller selects within the space of elemental variables a subspace (a manifold, UCM) corresponding to a value of a performance variable that needs to be stabilized. In the present study, we were interested in how movements of the individual segment center of mass (elemental variables) affect the whole-body center of mass (the performance variable) during balance control. Results: At the variance of task-irrelevant space, there was significant $test^*$ group interactions ($F_{1,16}=7.482$, p<.05). However, there were no significant main effect of the test ($F_{1,16}=.899$, p>.05) and group ($F_{1,16}=1.039$, p>.05). At the variance of task-relevant space, there was significant $test^*$ group interactions ($F_{1,16}=7.382$, p<.05). However, there were no significant main effect of the test ($F_{1,16}=.754$, p>.05) and group ($F_{1,16}=1.106$, p>.05). Conclusion: The results of this study showed that the 8 weeks training through the core training equipment for the elderly showed a significant decrease in the $Vcm_{TIR}$ and $Vcm_{TR}$. This result indicates that the core strength training affects the trunk stiffness control strategy to maintain balance in the standing position by minimizing total variability of individual segment CMs.

• Journal of information and communication convergence engineering
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• 제10권3호
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• pp.269-275
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• 2012

In this paper, we proposed a novel location estimation algorithm based on the concept of space-time signature matching in a moving target environment. In contrast to previous fingerprint-based approaches that rely on received signal strength (RSS) information only, the proposed algorithm uses angle, delay, and RSS information from the received signal to form a signature, which in turn is utilized for location estimation. We evaluated the performance of the proposed algorithm in terms of the average probability of error and the average error distance as a function of target movement. Simulation results confirmed the effectiveness of the proposed algorithm for location estimation even in moving target environment.

• Structural Engineering and Mechanics
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• 제49권1호
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• pp.111-128
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• 2014

The stochastic response surface method (SRSM) and the response surface method (RSM) are often used for structural reliability analysis, especially for reliability problems with implicit performance functions. This paper aims to compare these two methods in terms of fitting the performance function, accuracy and efficiency in estimating probability of failure as well as statistical moments of system output response. The computational procedures of two response surface methods are briefly introduced first. Then their capabilities are demonstrated and compared in detail through two examples. The results indicate that the probability of failure mainly reflects the accuracy of the response surface function (RSF) fitting the performance function in the vicinity of the design point, while the statistical moments of system output response reflect the accuracy of the RSF fitting the performance function in the entire space. In addition, the performance function can be well fitted by the SRSM with an optimal order polynomial chaos expansion both in the entire physical and in the independent standard normal spaces. However, it can be only well fitted by the RSM in the vicinity of the design point. For reliability problems involving random variables with approximate normal distributions, such as normal, lognormal, and Gumbel Max distributions, both the probability of failure and statistical moments of system output response can be accurately estimated by the SRSM, whereas the RSM can only produce the probability of failure with a reasonable accuracy.

• 한국항공우주학회지
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• 제42권7호
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• pp.544-551
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• 2014

발사체 개념설계 교육 및 추진기관 요구 분석에 활용을 목적으로 발사체 성능 해석 프로그램을 작성하였으며, 이를 이용하여 액체로켓 부스터를 장착한 한국형발사체의 성능해석을 수행하였다. 액체로켓 부스터의 성능은 75톤급 액체로켓엔진을 기본으로 하여 한국형발사체의 2단부 구조비를 참고하였다. 발사체의 성능해석은 700 km궤도를 목표로 부스터의 수를 2, 3, 4개로 늘려가며 분석하였다. 발사체 궤적은 비행환경을 고려한 2차원으로 가정하였다. 부스터를 장착하는 경우 탑재가능화물 무게는 3톤까지 증가함을 확인하였지만, 화물 능력은 상단부의 추력에 크게 제한받는 것으로 판단된다.

• Journal of information and communication convergence engineering
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• 제8권1호
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• pp.40-44
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• 2010

opportunistic spectrum access (OSA) allows unlicensed users to share licensed spectrum in space and time with no or little interference to primary users, with bring new research challenges in MAC design. We propose a cognitive MAC protocol using statistical channel information and selecting appropriate idle channel for transmission. The protocol based on the CSMA/CA, exploits statistics of spectrum usage for decision making on channel access. Idle channel availability, spectrum hole sufficiency and available channel condition will be included in algorithm statistical information. The model include the control channel and data channel, the transmitter negotiates with receiver on transmission parameters through control channel, statistical decision results (successful rate of transmission) from exchanged transmission parameters of control channel should pass the threshold and decide the data transmission with spectrum hole on data channel. A dynamical sensing range as a important parameter introduced to maintain the our protocol performance. The proposed protocol's simulation will show that proposed protocol does improve the throughput performance via traditional opportunistic spectrum access MAC protocol.

• 한국항행학회논문지
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• 제12권1호
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• pp.54-60
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• 2008

일반적으로 무선통신 시스템은 채널 상에서 발생하는 페이딩, 음영효과, 전파감쇠, 잡음 및 간섭 등에 의해 신호의 신뢰성이 크게 저하된다. 따라서 멀티미디어 데이터들을 열악한 무선통신 채널에서 안정적으로 전송하기 위해서는 보다 신뢰성 있는 시스템이 필요하다. 본 논문에서는 무선통신 환경에서 보다 신뢰성 있는 정보 전송을 위해 STBC의 다이버시티 이득과 STTC의 채널 효율성, 코딩 이득 및 다이버시티 이득을 동시에 갖는 STTC 기반 STBC 시스템을 고려하고 송수신기 사이의 채널 간 상관 값을 갖는 슬로우 페이딩 채널환경에서 성능을 분석하였다.

• 수산해양교육연구
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• 제15권2호
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• pp.184-192
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• 2003

When the present Learning System for Computer-Related Subjects Using WBI is implemented on the Web with the above characteristics to help students to study computer subjects without any limitations of time or space, they can easily attain the goals of learning, have computer-utilizing abilities or information capacity, and enhance their capabilities for self-initiative learning. This system enables the learners to carry out 'plan-do-see' for the contents of learning initiatively. The learners can study the practice part of the curriculum using multi-media, such as motion pictures, voices, images, and sound effects, vividly with a sense of actual presence. It helps the students to have an active attitude toward leaning afterward. without meeting the teacher or without any storage media, the leaners can submit their assignments or materials for performance evaluation via the Internet.

• Geomechanics and Engineering
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• 제17권4호
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• pp.385-392
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• 2019

The present fractional-order plasticity models for granular soil are mainly established under the triaxial compression condition, due to its difficult in analytically solving the fractional differentiation of the third stress invariant, e.g., Lode's angle. To solve this problem, a three dimensional fractional-order elastoplastic model based on the transformed stress method, which does not rely on the analytical solution of the Lode's angle, is proposed. A nonassociated plastic flow rule is derived by conducting the fractional derivative of the yielding function with respect to the stress tensor in the transformed stress space. All the model parameters can be easily determined by using laboratory test. The performance of this 3D model is then verified by simulating multi series of true triaxial test results of rockfill.

• 가족자원경영과 정책
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• 제16권2호
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• pp.187-210
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• 2012

Pumasi and Cooperative Child Care Sharing have had positive results among participants and show possibilities of spreading out to the community in general. However, performance was not proved where it is clarified, and the experience of 23 local Healthy Family Support Centers have that ran the demonstration project were unable to be collected. It is the point of time when the initial backing up is important but the centers do not have the systematic support. Therefore, this research presents an effective management plan through qualitative research involving Pumasi participants and person in charge. The operation strategies by the stage of the project were as follows: First, in the beginning stage, the person in charge establishes the target and vision of the project. Second, when comprising the Pumasi team, it was necessary to consider their characteristics according to the team organization subjects. Third, it is necessary to extend the turn-off time and provide many programs so that the various populations can participate. Fourth, in the advertising step, word of mouth and individual contact needs to be utilized. Fifth, in a medium or small city or an urban-rural complex area, the person in charge should support the participants' Pumasi activities. Sixth, various programs such as a passive and active parent education program and Pumasi education program for the leader needs to be provided for the activation of Pumasi activities. Lastly, a cooperative child care sharing location needs to be constructed by the duality system of the base space and outer space. In this location, the inside play space for the children is essential.