• Journal of Communications and Networks
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• 제15권1호
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• pp.77-86
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• 2013

Cognitive radio (CR) has emerged as one of effective methods to enhance the utilization of existing radio spectrum. Main principle of CR is that secondary users (SUs) are allowed to use the spectrum unused by primary users (PUs) without interfering PU's transmissions. In this paper, PUs operate on a slot-by-slot basis and SUs try to exploit the slots unused by PUs. We propose OSA protocols in the single channel and we propose an opportunistic spectrum access (OSA) protocols in the multi-channel cognitive radio networks with one control channel and several licensed channels where a slot is divided into contention phase and transmission phase. A slot is divided into reporting phase, contention phase and transmission phase. The reporting phase plays a role of finding idle channels unused by PUs and the contention phase plays a role of selecting a SU who will send packets in the data transmission phase. One SU is selected by carrier sense multiple access / collision avoidance (CSMA/CA) with request to send / clear to send (RTS/CTS) mechanism on control channel and the SU is allowed to occupy all remaining part of all idle channels during the current slot. For mathematical analysis, first we deal with the single-channel case and we model the proposed OSA media access control (MAC) protocol by three-dimensional discrete time Markov chain (DTMC) whose one-step transition probability matrix has a special structure so as to apply the censored Markov chain method to obtain the steady state distribution.We obtain the throughput and the distribution of access delay. Next we deal with the multi-channel case and obtain the throughput and the distribution of access delay by using results of single-channel case. In numerical results, our mathematical analysis is verified by simulations and we give numerical results on throughput and access delay of the proposed MAC protocol. Finally, we find the maximum allowable number of SUs satisfying the requirements on throughput and access delay.

• 한국기록관리학회지
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• 제13권1호
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• pp.181-187
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• 2013

본 논문은 1694년~1921년간의 몽골의 공문서 제도, 공문서 조직 및 기록전통에 대해서 소개하고자 한다. 몽골의 현대 기록관리는 1912년에 시작되었다. 몽골은 공문서를 발송하고 수령하며, 발송하고 수령된 공문서를 등록하기 위한 특별법이 제정되어 있었다. 공문서는 칸의 칙령과 정책을 전달하고, 또한 내부 문제를 다루기 위해 사용되었다. 1911년 독립 이후에 역사기록이 수집되고 보존되었다. 기록관리자와 아키비스트는 몽골 기록 관리법에 의해서 양성되고 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권2호
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• pp.687-701
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• 2020

In the production of industrial fabric, it needs automatic real-time system to detect defects on the fabric for assuring the defect-free products flow to the market. At present, many visual-based methods are designed for detecting the fabric defects, but they usually lead to high false alarm. Base on this reason, we propose a Sobel operator combined with patch statistics (SOPS) algorithm for defects detection. First, we describe the defect detection model. mean filter is applied to preprocess the acquired image. Then, Sobel operator (SO) is applied to deal with the defect image, and we can get a coarse binary image. Finally, the binary image can be divided into many patches. For a given patch, a threshold is used to decide whether the patch is defect-free or not. Finally, a new image will be reconstructed, and we did a loop for the reconstructed image to suppress defects noise. Experiments show that the proposed SOPS algorithm is effective.

• Structural Engineering and Mechanics
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• 제17권3_4호
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• pp.429-444
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• 2004

The ambient vibration measurement is a kind of output data-only dynamic testing where the traffics and winds are used as agents responsible for natural or environmental excitation. Therefore an experimental modal analysis procedure for ambient vibration testing will need to base itself on output-only data. The modal analysis involving output-only measurements presents a challenge that requires the use of special modal identification technique, which can deal with very small magnitude of ambient vibration contaminated by noise. Two complementary modal analysis methods are implemented. They are rather simple peak picking (PP) method in frequency domain and more advanced stochastic subspace identification (SSI) method in time domain. This paper presents the application of ambient vibration testing and experimental modal analysis on large civil engineering structures. A 15 storey reinforced concrete shear core building and a concrete filled steel tubular arch bridge have been chosen as two case studies. The results have shown that both techniques can identify the frequencies effectively. The stochastic subspace identification technique can detect frequencies that may possibly be missed by the peak picking method and gives a more reasonable mode shapes in most cases.

• 대한안전경영과학회지
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• 제4권2호
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• pp.57-70
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• 2002

Back pain is painful for people at a lower lumber(L4/L5 or L5/S1). It is experienced as a most frequent disaster 70％ of workers have suffered from back-pain. Especially, the occurrence rate of back pain for nurses is very high. Therefore, this study investigates female nurses who worked as a part of a medical cost management team, which mainly deal with the medical insurance in a general hospital at Seoul area. These nurses had different job tasks, which used computers for 50％ of their time, so it can be treated as VDT workers. As a first step of this project, a muscle fatigue was measured for these special VDT workers. First, survey for nurses was conducted to figure out what is a real problem of them. Second, to evaluate an experimental data, a medical cost management team was chosen for subjects. Areas of measurement were 3 places that were the trapezius (TR), the medial deltoid (MD), and the erector spine muscle (ES: L4/L5). These areas are most frequently used, so they were chosen for this study. Measurements were taken before work and after work. From these measurements, it was revealed that a fatigue really comes from their main VDT task excluding natural fatigue after work, so their work environment need to be corrected.

• Journal of Electrical Engineering and Technology
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• 제9권5호
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• pp.1780-1787
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• 2014

Arterial oxygen saturation ($SpO_2$) monitoring for newborns requires special attention in neonatal intensive care units (NICUs). Newborns have very low photo-plethysmogram (PPG) amplitudes and their body movements are difficult to contain. Hardware design and its associated signal processing algorithms should be robust enough so that faulty measurements can be avoided. In this study, improved designs were implemented to deal with low perfusion, motion artifact, and the influence of ambient light. Dynamic range was increased by using different LED intensities and a feedback system. To minimize the effects of motion artifact and to discard other unqualified data, four additional algorithms were used, which were based on dual-trace detection, continuity of DC level, morphology of PPG, and simultaneity check of $SpO_2$. Our $SpO_2$ system was tested with newborns with normal respiration in the NICU. Our system provided fast, real-time responses and 100% artifact detection was accomplished under 84% of $SpO_2$.

• 한국통신학회논문지
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• 제31권11B호
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• pp.969-978
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• 2006

멀티미디어 서비스의 증가는 인터넷 콘텐츠의 새로운 국면으로 나타나고 있다. IP텔레폰, 화상채팅과 같은 멀티미디어 서비스는 대역폭, 지터, 패킷유실, 전송지연 듯의 네트워크 파라미터에 민감한 데이터이다. 멀티미디어 서비스의 QoS 보장을 위해서 RTP/RTCP를 이용하여 네트워크 상황을 판단하고 전송률을 조절하는 기법이 연구되고 있다. 본 논문에서는 최선형(Best-Effort) 서비스를 제공하는 현 인터넷 구조에서 RTP/RTCP 구조를 확장하여 단방향 전송 지연시간을 구하고 이를 이용하여 네트워크 상황을 판단하는 기법을 제안한다. 또한 단방향 전송지연을 이용하여 급변하는 네트워크 상황에 즉각적으로 대처하기 위한 동적인 RTCP 구조를 제안한다. 모의 실험결과 제안한 단방향 전송 지연 기법은 GPS를 이용한 단방향 전송 기법과 유사한 성능을 보였으며, 제안한 동적 RTCP 기법은 적은 RTCP RR패킷 전송으로 패킷 손실률이 감소하는 효과를 얻었다.

• 한국잠사학회:학술대회논문집
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• 한국잠사학회 1997년도 Progress and Future Development of Sericultural Science and Technology 40th Anniversary Commemoration Symposium
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• pp.1-21
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• 1997

Silk is praised "Queen of Fiber", which wrote a glorious page in the history of human adornment culture. Thanks to the development of science and technology, silk production has been increased dramatically during last half century. Nowadays, as "Healthy Fiber" silk lets all the globe to be forming the "Silk Boom" Like in other scientific fields, a great deal of progress has been made in sericultural science and technology, which also accelerated the development of multipurpose utilization of sercultural recourses. The main tendency of the sericulture development is raising the quality of cocoon, and at the same time, increasing the output per unit mulberry area and labor production efficiency. The chief measure of raising the cocoon quality is breeding and selecting the new mulberry and silkworm varieties, preventing and curing the diseases and pests and improving the environment of mounting, and the symble for increasing the labor productivity is carrying out the technological system of saving labor and operation ease, and enlarging the production scale. As a natural protein fiber, silk will be still a favorite with human in the next century, because its structure and properties can not be replaced by other any fiber. The 21st century is the biological time, and measures of developing sericulture will use the achievement on the field of molecular biology and biotechnology to carry out the molecular breeding, development regulating, silkworm rearing industrializing, exploiting the new silk and its new usage, utilizing the sericultural resources, and producing the special protein from silkworm as a host of expressing exogenous genes so that make the sericulture to contribute more what it can do for the human being.

• 한국정보통신학회논문지
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• 제23권1호
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• pp.97-102
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• 2019

최근 들어 산업현장에서의 재난 사고는 해마다 증가하고 있는 추세이다. 조선업의 경우 밀폐된 공간이 많기 때문에 작업시 발생하는 각종 유해가스에 대한 이슈와 작업장 구조가 복잡하기 때문에 사고가 발생하였을 경우 격벽으로 인한 통신, 사용자 위치추적의 어려움 등에 대한 문제점이 제기된다. 이러한 상황에서 여러 가지 재해나 재난이 발생할 경우 작업자의 피난이나 구조에 있어 상당한 어려움이 발생한다. 이에 본 논문에서는 밀폐된 공간에서 각종 재해나 재난이 발생할 경우 사고를 사전에 방지하기 위한 통합안전시스템을 제안한다. 제안하는 통합안전시스템은 작업자들에 대한 위치정보의 데이터를 실시간 관리하고 작업장에서 발생하는 가스, 산소, 이산화탄소 등의 수치도 실시간으로 관리가 가능하기 때문에 사고를 미연에 방지할 수 있다.

• 기술혁신학회지
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• 제10권3호
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• pp.406-430
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• 2007

본고는 제약분야 라이센싱 거래의 기초가 되는 주요 경제적 조건에 근거한 분석적 접근방법을 검토하기 위한 것이다. 그 목적은 관련된 주요 요인들 간의 관계에 대한 이해를 높이는 것이다. 여기에서 제기되는 몇 가지 논점은 다음과 같다. 즉, 신약개발의 특징인 대규모 투자, 고위험 및 긴 개발기간 등의 수익에 대한 효과, 최종 매출수준과 영업이익이 적정 로열티율에 미치는 효과, 선불금 및 신약개발 단계별로 지불될 마일스톤 기술료와 약품이 시장에 진입된 후에 지불될 기술료간의 관계 등이 그것이다. 본고에서는 먼저 제약분야 기술이전 거래의 로열티 결정을 위한 사전 단계로서, 기술가치평가의 주요 방법과 특징을 살펴보고, 다음으로 로열티 결정을 위한 주요요소인 기대이익, 매출액, 각종 비용, 투자 등의 측정방법을 검토한다. 그리고 이러한 주요 요소의 측정에 기초하여 로열티와 이윤율, 기술제공자와 기술도입자 간의 이익배분, 로열티의 산출과 결정방식에 대해 고찰하고자 한다.