• 전자공학회논문지CI
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• 제49권3호
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• pp.62-73
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• 2012

저속, 저전력, 저가의 특징을 갖는 IEEE 802.15.4 standard는 무선 센서 네트워크 환경에서 효율적이다. IEEE 802.15.4 표준에서 사용하는 다양한 토폴로지 중에서도 많은 노드들이 참여하는 클러스터-트리 토폴로지는 싱크 노드 주변에 트래픽이 집중되어 전송 지연과 에너지 소모 증가 및 데이터 손실을 초래하게 된다. 본 논문에서는 효율적인 데이터 전송을 위해 패킷간의 충돌을 최소화하고 제한된 에너지를 효율적으로 사용하기 위해 액티브 구간을 동적으로 할당하는 MRS-DCA알고리즘을 제안한다. 이 알고리즘은 IEEE 802.15.4 standard의 액티브구간에 RP(Reservation Period)를 할당하여 사용한다. 또한, EWMA를 이용한 할당 알고리즘으로 트래픽을 예측하고 이것을 기반으로 RP와 CAP를 동적으로 할당함으로써 안정적인 데이터 전송을 보장한다. 제안하는 MRS-DCA알고리즘의 성능 비교를 위하여 IEEE 802.15.4, DCA scheme과 비교한 결과, 액티브 구간의 단축으로 전력 소모가 적어지고 충돌 회피율의 상승으로 높은 전송률을 보이는 것을 확인하였다.

• International Journal of Contents
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• 제11권1호
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• pp.52-61
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• 2015

In the past decade, East Asian Research has received attention from researchers as well as in South Korea society-at-large. The broad category of East Asian Research includes various disciplinary fields, such as "history, economics, and politics; however, few studies have used quantitative analysis to explore its development. In this paper, we used network analysis to identify the disciplines and active research areas, focusing on productivity, collaboration patterns, and citation networks of East Asian Research in South Korea. For this study, 6,646 journal publications related with East Asian Research and indexed by KCI (Korean Citation Index) during the 10-year period of 2004-2013 were considered. Results show that East Asian Research was led during this period by sole-researchers, rather than interdisciplinary studies. Moreover, a co-institution network represents active institutions with a high degree and collaborative centrality. In terms of journal-journal citation networks, journals belonging to both "history" and "Korean literature" disciplines were dominant.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권1호
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• pp.123-140
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• 2011

In this paper, we propose an Energy Efficient Media Access Control (EE-MAC) protocol for wireless sensor networks. The proposed scheme is designed to save power consumption and guarantee quality-of-service for real-time traffic. EE-MAC uses the superframe structure which is bounded by the transmission of a beacon frame and can have an active and an inactive portion. The active period is divided into the contention free period (CFP) for real-time traffic transmission and the contention access period (CAP) for non-real-time traffic transmission. We propose the exclusively allocated backoff scheme which assigns a unique backoff time value to each real-time node based on bandwidth allocation and admission control. This scheme can avoid collision between real-time nodes by controlling distributed fashion and take effect a statistical time division multiple access. We also propose the algorithm to change the duty cycle adaptively according to channel utilization of media depending on network traffic load. This algorithm can prolong network lifetime by reducing the amount of energy wasted on idle listening.

• 한국주거학회논문집
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• 제21권2호
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• pp.77-86
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• 2010

Korean population is now aging at an unprecedented rate. Fertility decline together with rapid improvements in life expectancy is the dominant demographic trend. As human life and housing environment are inseparably related to each other, the importance of conditions of housing environment for active aging among seniors has been received considerable attention as vital ones to expand the independency period of seniors. The purpose of this case study is to identify relationships between environmental affordance and perceived holistic health of the active elderly living in a retirement community located in Seoul. With spending time personally in the community to observe their lives, the researcher could be in close rapport with the residents. After the period of getting familiar with each other, in-depth individual interview and focus group interview were conducted and then, qualitative analysis was completed. As a result, general evidences showed that perceived seniors' health on the whole was improved physically, socially, and mentally by moving into the community providing appropriate environment affordance with the older adults. The study presents that retirement relocation into an improper environment may be a negative challenge, however, it may positively influence on the health and well-being of those who live there if the environment properly supports seniors‘ needs physically and socially

• 한국동물학회지
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• 제16권2호
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• pp.109-118
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• 1973

동면전, 중, 후 및 활동기 동안 조선산개구리(Rana amurensis coreana Okada)의 위장관 점막내에 출현하는 enterochromaffin cell의 내분비성 분비과립의 변화를 형태학적으로 관찰하여 다음과 같은 결과를 얻었다. 1. 활동기 및 동면전, 중, 후기의 위장관 점막상피 내 enterochromaffin cell의 출현비율은 1: 1.5 :0.36 : 0.9로서 본 세포의 수는 활동기군에 비하여 동면전기군은 유의하게 증가하였으며 동면 중기군은 유의하게 감소하였다. 2. 활동기 및 동면전기군의 EC cell은 대체로 그 세포질내에 분비과립이 차있는 다과립성 및 중자등과립성 세포가 대다수였으나 동면중기 및 후기군에서는 희과립세포가 현저히 증가되었다. 3. EC cell의 형태학적 변화는 다른 신진대사 특히 내분비적 활성의 약화로 야기되는 생체의 적응현상에서 온 결과라고 추측된다.

• Nuclear Engineering and Technology
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• 제50권2호
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• pp.313-317
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• 2018

Licenses for the storage of spent nuclear fuel (SNF) and vitrified highly active waste in casks under dry conditions are limited to 40 years and have to be renewed for prolonged storage periods. If such a license renewal has to be expected since as in accordance with the new site selection procedure a final repository for spent fuel in Germany will not be available before the year 2050. For transport and possible unloading and loading in new casks for final storage, the integrity and the maintenance of the geometry of the cask's inventory is essential because the SNF rod cladding and the cladding of the vitrified highly active waste are stipulated as a barrier in the storage concept. For SNF, the cladding integrity is ensured currently by limiting the hoop stress and hoop strain as well as the maximum temperature to certain values for a 40-year storage period. For a prolonged storage period, other cladding degradation mechanisms such as inner and outer oxide layer formation, hydrogen pick up, irradiation damages in cladding material crystal structure, helium production from alpha decay, and long-term fission gas release may become leading effects driving degradation mechanisms that have to be discussed.

• 천문학회보
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• 제36권1호
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• pp.36.1-36.1
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• 2011

It is generally believed that eruptive phenomena in the solar atmosphere such as solar flares and coronal mass ejections (CMEs) occur in the solar active regions with complex magnetic structures. Magnetic helicity has been recognized as a useful parameter to measure the complexity such as twists, kinks, and inter-linkages of magnetic field lines. The objective of this study is to understand a long-term (a few days) variation of magnetic helicity in active regions and its relationship with the energy buildup and instability leading to flares and CMEs. Statistical studies of flare productivity and magnetic helicity injection in about 400 active regions were carried out. The temporal variation of magnetic helicity injected through the photosphere of active regions was also examined related to 46 CMEs. The main findings in this study are as follows: (1) the study of magnetic helicity for active regions producing major flares and CMEs indicates that there is always a significant helicity injection through the active-region photosphere over a long period of 0.5 - a few days before the flares and CMEs; (2) for the 30 CMEs under investigation, it is found that there is a fairly good correlation (linear correlation coefficient of 0.71) between the average helicity injection in the CME-productive active regions and the CME speed. Beside the scientific contribution, a major impact of this study is the observational discovery of a characteristic variation pattern of magnetic helicity injection in flare/CME-productive active regions which can be used for the improvement of solar eruption forecasting.

• 융합신호처리학회논문지
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• 제19권3호
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• pp.104-109
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• 2018

심전도와 심탄도를 무구속적으로 동시에 측정하는 시스템을 개발하였다. 제안된 시스템은 의자의 보조 등받이에 설치되어 맥파전달시간(PAT), Pre-ejection period (PEP) 등의 심혈관계 역학 정보를 일상생활에서 무구속적으로 측정하는 것을 목적으로 개발되었다. 본 연구에서는, 의자의 등받이에 부착된 용량성 능동전극과 용량성 접지를 이용한 간접접촉 심전도 (IDC-ECG) 측정 방법에 의해 무구속적으로 심전도를 측정하였으며, 등받이에 부착된 EMFi 압력 센서를 사용하여 무구속적으로 심탄도(ballistocardiogram)를 측정하였다. 제안된 시스템으로 심전도와 심탄도가 무구속적으로 동시에 측정됨을 확인하였으며, 측정된 심탄도는 피검자 사이에서 일정한 패턴을 보이는 것을 알 수 있었다. 또한 심전도의 Q파와 심탄도의 첫 번째 첨두간의 시간차가 pre-ejection period와 높은 상관관계를 보이는 것도 확인할 수 있었다. 이 연구에서 개발된 시스템은 심혈관계의 다양한 지표(심전도, 심박수, PAT, PEP 등)를 무구속적으로 일상생활에서 측정할 수 있음을 보였다.

• 전기학회논문지P
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• 제50권3호
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• pp.130-137
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• 2001

In this paper, we propose a new Active Noise Filter Control System which operate as a control performance when a adaptive filter fault. In this system, half-fixed filter which is new filter, connected to parallel with adaptive filter. An adaptive filler use to continuous parameter estimating, but adaptive filter is fault, half-fixed filter update newly data which is continuous estimating date each during sampling period. We simulate and apply the proposed active noise filter system to in the cylinder type duct. Experimental results show that proposed Active Noise Filter Control System has better control performance than existing filter which Eriksson's or Parallel Filter System in term of noise reduction.

• 한국의사학회지
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• 제14권1호
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• pp.79-108
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• 2001

Pyunjak is presumed to be Jinwallin who was active in early Chunchu period among five identically called doctors from early Chunchu period to Warring period. The name, Pyunjak, seems to be used as "special local doctor who goes around the country". This reflects the social atmosphere of the time that medical science and art were getting developed from royal household and government centered medicine to civilian-centered medicine.