• 한국산학기술학회논문지
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• 제18권9호
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• pp.9-17
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• 2017

자동차 및 철도 등 수송 시스템에서 무인화 운전으로의 진전으로 인해 시스템 운영 시 안전성의 확보는 필수불가결한 요소로 간주되어 왔다. 자동차 안전설계를 뒷받침하기 위해 제정된 기능안전 표준인 ISO 26262에서는 위험원 분석 및 평가 그리고 안전 설계를 수행할 때 시스템 설계 정보를 적절하게 반영함으로써 안전성이 확보되는 자동차 시스템을 구현하기 위한 절차가 제시되어 있다. 이에 따라 위험원 분석에 관해 많은 연구가 이루어졌는데, 주로 이미 운영되고 있는 유사 시스템 사례에 의존하여 설계 정보를 활용하였다. 먼저 물리 구성품 수준에서 설계정보를 추출하고, 이로부터 기능 들을 역추적 한 후에 위험원을 식별하는 방법이 연구되었다. 이러한 방법은 빠르고 쉽게 위험원의 식별이 가능하기는 하지만, 설계 요구사항이 변경되거나 새로운 시스템을 설계할 때에는 설계 정보를 제대로 반영할 수 없어 일부 위험원이 누락될 수 있는 가능성이 있다. 이러한 점을 해결하기 위해서 본 논문에서는 기능안전표준에서 제시하는 안전수명주기 모델의 위험원 분석 단계에서 효과적인 방법을 연구하였다. 구체적으로 시스템 개념 설계를 Top-Down 방식으로 수행하면서 확보한 설계 정보를 위험원 분석에 적절하게 활용하는 방법을 제안하였다. 먼저 시스템 개념 설계를 수행하고, 획득된 기능 설계 결과를 분석하였다. 그러고 나서 기능 분석 결과를 활용하는 기능기반 Fault Tree Analysis 방법을 제시하고 위험원 분석을 수행하였다. 또한 자동차 시스템에서의 안전 설계 사례 연구를 통하여 본 논문에서 제시하는 방법이 대상 시스템의 설계 정보가 체계적으로 반영되어 누락 가능성이 줄어든 위험원 분석이 가능함을 보여 주었다.

• 수산경영론집
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• 제38권3호
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• pp.25-51
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• 2007

Recently those who visit a fishing village is increasing. So the government's policymaker is interested in a tourism of fishing village. There are a lot of local governments that they turn it to good account to activate the fishing community. So they plan for the tourism facility in the fishing village and invest in it. The fishery facility can playa role in it. Nonetheless it is not playing a role in tourism facility. Though the breakwaters projecting far into the sea are good waterfront, most of them are not reflecting the function of it. And fishery facility producing seed is a good resource of eco-tourism, but it is yet a tourist potential. Although the artificial reef is going far toward promoting a fishery resource, it is seldom used as a tourism resource. The multiple functions of fishery facilities have to be improved to raise the investment effect of them. Especially the tourism function has to be added on their basic function. The multiple functions of fishery facilities is necessary to satisfy tourist's needs. In results, not only their value but also value of fishing village will be raised.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.125-128
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• 2000

This paper presents an energy function which provides the direct relationships between the system stability and parameters of the exciter system. The energy function is derived from the energy conservation law by using the first motion integral. he time derivative does not absolutely satisfy the seminegativeness. However dE/dt usually has big negative value just after the fault clearing so that the energy is rapidly decreased. In this situation, the system state can be obviously confined in a stable region if the intial energy is less than the UEP energy. With these observation, two theorems are developed regarding the state confinement and asymptotic stability. Based on two theorems a new approximated direct energy method is developed to analyze the transient stability with the consideration of the exciter control effects. The proposed method has been tested for a single-machine-infinite bus system.

• 디지털산업정보학회논문지
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• 제10권3호
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• pp.35-40
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• 2014

Many researches have been conducted to achieve improvement in distributed system that connects multiple computer systems via communication lines. Among others, the load balancing and file migration are considered to have significant impact on the performance of distributed system. The dynamic file migration algorithm common in distributed processing system involved complex calculations of decision function necessary for file migration and required migration of control messages for the performance of decision function. However, the performance of this decision function puts significant computational strain on computer. As one single network is shared by all computers, more computers connected to network means migration of more control messages from file migration, causing the network to trigger bottleneck in distributed processing system. Therefore, it has become imperative to carry out the research that aims to reduce the number of control messages that will be migrated. In this study, the learning automata was used for file migration which would requires only the file reference-related information to determine whether file migration has been made or determine the time and site of file migration, depending on the file conditions, thus reflecting the status of current system well and eliminating the message transfer and additional calculation overhead for file migration. Moreover, mathematical model for file migration was described in order to verify the proposed model. The results from mathematical model and simulation model suggest that the proposed model is well-suited to the distributed system.

• International Journal of Precision Engineering and Manufacturing
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• 제4권6호
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• pp.5-11
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• 2003

The number of the enterprises which utilize network technology has been increasing for solving problems such as productivity improvement, market trend analysis, and material collection for making decision. Especially, the management of equipment and the recovery time reduction when machines break down are very important factors in productivity improvement of the enterprise. Currently, most of the remote trouble diagnosis of equipment using the internet have just one function of transmitting the trouble information to the user. Therefore it does not directly reflect the user's recovery experience or the developer's new recovery methods. If the user's experienced recovery methods or the developer's recovery methods as well as the basic recovery methods are reflected online or on the internet, it makes it possible to recover faster than before. In this paper, we develop a Remote Monitoring Server (RMS) for chip mounters, and make it possible to reduce the recovery time by reflecting the user's experience and developer's new methods in addition to presenting the basic recovery methods. For this, trouble recovery concept will be defined. Based on this, many functions(trouble diagnosis, the presentation of the basic recovery methods, user's and developer's recovery method, counting function of the trouble number of each code, and presentation of usage number of each recovery methods) were developed. By utilizing the reports of the actual results of chip mounter and the notice function of the parts change time, the rate of operation of the chip mounter can be improved.

• 한국환경교육학회지:환경교육
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• 제11권2호
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• pp.238-251
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• 1998

Environmental education, which has been thought as the most fundamental solution to environmental problems, should be performed not only in school but also in home and society with a long-term plan. In line with this, environmental-friendly attitude in daily life should be achieved by the perception of the vital environmental principle-new understanding of relation between nature and human being. It is in the city park that children in urban area, who has little opportunity to contact nature, have rather easier access to nature and realize the principle. Despite such great potential, the city park in Korea has not played its pivotal role because of lack of both facilities and activities. In addition, existing studies on this issue are not satisfactory. Therefore, this study is aimed at analyzing and evaluating city parks' environmental education function, potential and problems according to their types, then offering practical reform measures and programs in order to make students better understand the parks as an everyday natural experience spot. These plans are not based on full-scale revision, instead focuses on optimizing potential of existing natural environment and parks. Additionally, activities to experience various nature are included in the study. The value of city park is not decided by the park itself, but by its relationship with visitors. Environmental education function of city park is not confined to building up facilities and providing programs. It also should be complemented and improved, reflecting visitors' opinions and evaluation of environmental education.

• 한국가구학회지
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• 제28권2호
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• pp.95-102
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• 2017

In the process of changing from modern society to contemporary society, innovation of various fields is considered as important with rapid social change and one of the consequences of this changing movement is the innovation of living space. In this paper, based on this motive, we will study a modular shelf that can create a private space, and serve function like role of partition that delimits space in the one-room. Modular shelves can provide openness, closeness, and autonomy to individual spaces in a one-room space without space divisions. In a small one-room for residential purpose, it is able to function effectively to show the atmosphere of personal space and display small items reflecting personal taste in addition to the function of storing books and items. In addition, a modular shelves considering disassembly and movement are proposed in order to take advantage of one-room that can make different space configurations as needed. It is aim to suggest a basic modular shelves structure that used traditional Chinese wood-joints during which techniques was sturdy while reducing the use of timber. Futhermore, the purpose of this study is to study the design of shelf furniture that can add individuality.

• 말소리와 음성과학
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• 제13권3호
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• pp.21-29
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• 2021

The present study investigated how one's cognitive resources are related to speech perception by examining Korean speakers' executive function (EF) capacity and its association with voice onset time (VOT) and f0 sensitivity in identifying Korean stop laryngeal categories (/t'/ vs. /t/ vs. /t^h/). Previously, Kong et al. (under revision) reported that Korean listeners (N = 154) in Seoul and Changwon (Gyeongsang) showed differential group patterns in dialect-specific cue weightings across educational institutions (college, high school, and elementary school). We follow up this study by further relating their EF control (working memory, mental flexibility, and inhibition) to their speech perception patterns to examine whether better cognitive ability would control attention to multiple acoustic dimensions. Partial correlation analyses revealed that better EFs in Korean listeners were associated with greater sensitivity to available acoustic details and with greater suppression of irrelevant acoustic information across subgroups, although only a small set of EF components turned out to be relevant. Unlike Seoul participants, Gyeongsang listeners' f0 use was not correlated with any EF task scores, reflecting dialect-specific cue primacy using f0 as a secondary cue. The findings confirm the link between speech perception and general cognitive ability, providing experimental evidence from Korean listeners.

• 한국해양공학회지
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• 제35권3호
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• pp.183-190
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• 2021

Tomographic particle image velocimetry (PIV) is a widely used method that measures a three-dimensional (3D) flow field by reconstructing camera images into voxel images. In 3D measurements, the setting and calibration of the camera's mapping function significantly impact the obtained results. In this study, a camera self-calibration technique is applied to tomographic PIV to reduce the occurrence of errors arising from such functions. The measured 3D particles are superimposed on the image to create a disparity map. Camera self-calibration is performed by reflecting the error of the disparity map to the center value of the particles. Vortex ring synthetic images are generated and the developed algorithm is applied. The optimal result is obtained by applying self-calibration once when the center error is less than 1 pixel and by applying self-calibration 2-3 times when it was more than 1 pixel; the maximum recovery ratio is 96%. Further self-correlation did not improve the results. The algorithm is evaluated by performing an actual rotational flow experiment, and the optimal result was obtained when self-calibration was applied once, as shown in the virtual image result. Therefore, the developed algorithm is expected to be utilized for the performance improvement of 3D flow measurements.

• 감성과학
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• 제22권3호
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• pp.21-34
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• 2019

이 연구는 노년기 인지기능 및 생리적 건강상태와 관련 있는 정량화 뇌파의 Alpha 고유리듬 피크 위치 및 진폭의 출현 유무가 정신적·육체적 스트레스, 주의집중 등의 뇌파 지표들과 심박변이도 지표 간에 어떠한 관련성과 임상적 의미가 있는지 알아보고자 하였다. 이를 위하여 평균 73세 남녀 노인 76명을 대상으로 전두엽 2채널 뇌파와 1채널 심전도를 동시에 측정 가능한 장치를 이용하여 폐안시 EEG, HRV를 측정하였다. 의미있는 분석 결과는 다음과 같다. 첫 번째, Alpha 고유리듬피크 위치와 상관없이 고유리듬 진폭이 높게 잘 나타난 집단은 낮은 집단에 비해 정신적 스트레스에 대한 저항도는 높고, 육체적 스트레스는 낮게 나타나는 상관성을 보였다. 두 번째, 심박변이도의 HRV index, SDNN, RMSSD 지표는 집단 구분에 상관없이 공통적으로 서로 간 높은 양의 상관성을 보였다. 세 번째, Alpha 고유리듬 진폭이 잘 나타나지 않은 집단에서 좌·우뇌 Alpha 비대칭이 커질수록 육체적 스트레스를 반영하는 Delta/Alpha 비율과 주의집중 저하를 반영하는 Theta/SMR 비율도 커지는 상관성을 보였다. 네 번째, Alpha 고유리듬피크가 느린 리듬쪽에 위치한 집단은 빠른 리듬 쪽에 위치한 집단에 비해 Theta/SMR 비율이 높게 나타나 주의집중도 저하와 관련이 있음을 의미하였다. 따라서 정량화 뇌파의 Alpha 고유리듬 피크 위치 및 진폭의 출현 유무는 노년기 인지기능 및 생리적 건강상태를 반영하는 지표로 활용 가능성이 있음을 시사하였다.