• Information and Communications Magazine
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• v.31 no.10
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• pp.87-93
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• 2014

대기중 사운드 통신(Aerial acoustic communication)은 공기를 매질로 삼아서 전파되는 소리에 정보를 싣는 통신 기술로 스피커와 마이크 등의 오디오 인터페이스로 신호를 송수신하는 방식을 의미한다. 오늘날 많은 사람들이 사용하는 스마트 기기의 내장 마이크를 수신 인터페이스로 활용할 수 있다는 장점 때문에 대기중 사운드 통신을 기반으로 한 다양한 기술 및 어플리케이션 개발이 이루어지고 있다. 본 고에서는 최근 대기중 사운드 통신 기술 동향을 살펴보고 대기중 사운드 통신의 특성으로부터 기인하는 기술적인 어려움을 짚어본다. 또한, 대기중 사운드 통신 기술 기반의 응용 서비스를 알아본다.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2001.11a
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• pp.127-128
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• 2001

라돈은 사람들이 노출되는 자연 방사능 중 가장 큰 부분을 차지하며, 전체 자연 방사능 중 약 50%를 차지한다. 라돈의 인체영향 대부분이 호흡을 통한 인체 내에 유입에 의한 것으로 알려져 있다. 라돈에 의한 인체영향과 대기 중 오염물질의 장거리 이동에 대한 연구를 위해 대기 중 라돈의 거동특성 연구가 필요하다. 또한 라돈농도의 지역적 분포와 시간변화에 대한 정보는 지역적 특성, 라돈의 배출, 대기 중 습성에 대한 라돈 연구에 중요하다. (중략)

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.1-3
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• 2018

국제해사기구(IMO)의 황천 중 조종성능 유지를 위한 최소추진마력 기준 제정과 국제수조협회(ITTC)의 파도 중 조종성능 추정에 대한 관심이 증가하면서 파도 중 조종성능 추정기술에 대한 연구가 많이 수행되고 있다. 본 연구에서는 파도 중 조종성능을 추정하는 기법중 하나인 시뮬레이션 기법 중에서 조종운동만을 시뮬레이션하는 간이 시뮬레이션을 수행하였고, 시뮬레이션 결과를 검증하기 위하여 자유 항주시험결과가 존재하는 S-175 컨테이너선에 대한 시뮬레이션을 수행하여 비교하였다.

• Journal of Bio-Environment Control
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• v.3 no.2
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• pp.119-127
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• 1994

This study was conducted to investigate the effects of temperature and light conditions on the vigor and growth responses of red pepper(Capsicum annuum L.) seedlings in the nonheated plastic houses with triple and quadruple coverings during winter. The results obtained were as follows ; 1. The growth in terms of plant height, number of leaves, leaf area and dry weight of each organ was reduced up to 50% in the triple coverings compared to quadruple ones. The greatest difference between the triple coverings and quadruple ones was the leaf area, showing two to five times larger in the quadruple ones. Therefore, the differences of the early environmental conditions during raising seedling stage was well reflected. 2. The leaf expansion in the early stage of seedling was delayed in the triple coverings and subsequently crop growth rate(CGR) significantly reduced. The specific leaf area (SLA) in the triple coverings was less than quadruple ones. The net assimilation rate (NAR) was increased in the early stage of seedlings and then reduced in the quadruple coverings. In triple ones, however, the great reduction showed at six weeks after sowing and then increased sharply. 3. The linear relationship among leaf area, total dry weight and leaf dry weight was observed in the all experimental areas, while between leaf area and crop growth rate only in the quadruple coverings, and between leaf area and net assimilation rate in both triple and quadruple ones. 4. The dry matter partitioned to the leaf increased up to six weeks after sowing in the triple coverings but reduced in the stem and root. However, the adverse results were obtained in the quadruple ones. 5. In the triple coverings, the number of branches showed the exponential increment while fruit weight showed linear increment in both triple and quadruple ones. Higher yield was obtained in the quadruple ones. 6. The shoot dry weight among the characteristics of seedlings was greatly contributed to the yield of red pepper after transplanting. Accordingly, one of the decisive criterion for good quality of red pepper seedlings was determined by the highest correlation between shoot dry weight of growing plant and fruit yield of pepper plant.

• Journal of The Korean Society of Grassland and Forage Science
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• v.13 no.4
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• pp.251-256
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• 1993

This experiments was carried out to evaluate the potential winter hardiness of tall fescue varieties based on the data of dry weight of plant per relative tiller appearance rates(DW/RTAR) in mountainous pastures of Taekwalyon area. The results obtained were as follows; 1. The varieties were classified into 2 groups by dry weight of plant per relative tiller appearance rates (DW/RTAR). Thus. Forager and Fuego belong to the group with more than 2.0 in DW/RTAR but Barcel, Barvetia, Demeter, Enforcer. Johnstone, Safe and Stef belong to the group with less than 2.0 in DW/RTAR respectively. 2. The dry weight of plant per relative tiller appearance rates(DM/RTAR) and dry weight of plant(DW) of 1st cutting were significantly positive correlated with number of heading tillers and dry weight of heading tillers. 3. The dry weight of plant per relative tiller appearance rates(DW/RTAR) was significantly positive correlated with dry weight of plant(DW) of final cutting and of 1st cutting. 4. The varieties with high DW/RTAR showed a high dry weight of plant(DW) of 1st cutting. Accordingly, it was concluded that DW/RTAR is a valuable character for evaluating potential winter hardiness of tall fescue on mountainous pastures of Taekwalyon area.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.2
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• pp.161-172
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• 2017

To evaluate radiological impact from the operation of a low- and intermediate-level radioactive waste disposal facility, a logical presentation and explanation of expected accidental scenarios is essential to the stakeholders of the disposal facility. The logical assessment platform and procedure, including analysis of the safety function of disposal components, operational hazard analysis, operational risk analysis, and preparedness of remedial measures for operational safety, are improved in this study. In the operational risk analysis, both design measures and management measures are suggested to make it possible to connect among design, operation, and safety assessment within the same assessment platform. For the preparedness of logical assessment procedure, classification logic of an operational accident is suggested based on the probability of occurrence and consequences of assessment results. The improved assessment platform and procedure are applied to an operational accident analysis of the Korean low- and intermediate-level radioactive waste disposal facility and partly presented in this paper.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.430-437
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• 2018

For a ship navigating in waves, added resistance, sway force and yaw moment due to waves differ from still water conditions, which affects the maneuverability of the ship. Therefore, it is important to estimate the sway force and yaw moment generated by waves. In this study, numerical simulations were carried out to calculate the hydrodynamic forces acting on a barge in still water and waves using CFD. Based on the results, the characteristics of course stability of a barge were investigated and analyzed. The hydrodynamic forces acting on the barge in waves were stronger than in still water, and it was confirmed that hydrodynamic forces become greater as wavelength becomes longer. In long wavelength regions, the (-) value of the yaw damping lever was larger than in still water. However, in short wavelength regions and when wavelength coincided with the length of the ship, values were smaller than in still water. In this region, it can be assumed that course stability improved. In other words, in long wavelength regions, the course stability of the barge was worse than in still water and short wavelength regions. Therefore, attention is required for safe navigation in long wavelength regions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3A
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• pp.357-366
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• 2008

This study addresses the analysis of the behavioral characteristics of bridge expansion joints under wheel loading through wheel load test and the proposal of relevant wheel load specifications for expansion joints. To that goal, specimens of rail and finger expansion joints that are widely used in Korea were fabricated and subjected to static wheel load test using a real tire wheel. The wheel load distribution factor in the rail and finger expansion joints in contact with the wheel load was evaluated. The evaluation revealed that the portion of load sustained by the central rail of rail expansion joint was decreasing with larger wheel load, and that the portion of load sustained by the finger expansion joint was practically insensitive to the increase of the contact area and remained nearly constant. Since the wheel load characteristics showed large difference compared to former design specifications, it appears necessary to prepare rational specifications relative to the distribution of the wheel load contact pressure for the design of expansion joints.

• Information and Communications Magazine
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• v.33 no.4
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• pp.99-106
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• 2016

본고에서는 5세대 이동통신 핵심기술 중 하나인 전이중 (full-duplex) 전송기술의 이득을 성취할 수 있는 새로운 접근 방법인 가상 전이중 (virtual full-duplex) 중계전송 기법에 대해서 알아본다. 이는 아직 실제적인 제약들을 해결해야 하는 전이중 중계전송 기술의 대안으로 반이중 (half-duplex) 중계기 2개를 하나의 가상 중계기로 고려함으로써 네트워크 차원에서는 송신과 수신이 동시에 이루어지도록 하여 전이중 중계전송의 효과를 얻는 기술이다. 본고에서는 먼저, 중계기에서 메모리를 고려하지 않고, 2개의 중계기를 번갈아 가면서 사용하는 2경로 (two-path) 교차 (alternating) 중계전송 기법을 살펴보고, 다음으로 중계기에 버퍼를 장착한 다수 중계기 네트워크에서 가상 전이중 중계전송 기법에 대해서 알아본다.

• Journal of Environmental Health Sciences
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• v.32 no.5 s.92
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• pp.418-423
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• 2006

이 사례연구는 누수가 있었던 고층 아파트의 공기중 진균 오염 실태를 조사하고, 이를 개선하기 위해 취해진 복원방법의 효과를 평가하기 위해 실시하였다. 공기중 진균은 주로 엔더슨 샘플러를 사용하여 측정하였다. 누수가 있었던 아파트의 복원 전 공기중 진균 농도는 매우 높았다(평균: $51,000\;cfu/m^{3}$, 기하평균: $40,163\;cfu/m^{3}$). 고농도의 오존처리와 오염된 벽체 철거 후 공기중 진균 농도는 상대적으로 매우 낮아졌으며(평균: $1,118\;cfu/m^{3}$, 기하평균: $899\;cfu/m^{3}$), 제거효율은 96.3%로 나타났다. 철거되지 않고 남아 있던 인근 벽체의 벽지를 제거하고 살진균제 처리를 실시한 결과, 공기중 진균 농도는 상대적으로 안전한 수준까지 낮아졌으며(평균: $95\;cfu/m^{3}$, 기하평균: $88\;cfu/m^{3}$), 제거효율은 99.7 %로, 나타났다. 결론적으로, 누수가 있었던 아파트의 공기중 진균 농도는 매우 높은 상태로 오염이 심한 상태이었으나, 본 연구에서 적용한 복원방법들은 공기중 진균 농도 저감에 있어서 매우 높은 효율을 나타냈다.