• Review of KIISC
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• v.13 no.1
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• pp.42-55
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• 2003

차세대 광 인터넷 백본망 기술은 WDM(Wavelength Division Multiplexing)기반의 고속 대용량 전광 전달망인 AOTN (All-Optical Transport Network)으로 발전하고 있고, 가입자의 원활한 멀티미디어 서비스의 제공을 위한 망 생존성 보장이 중요한 이슈로 부각되고 있다. 특히 광소자의 고유한 특성을 교묘히 이용하는 물리적 공격은 AOTN의 투명한 데이터 전달 특성으로 인해 기존의 오버헤드를 이용한 관리 시스템이 더 이상 유효하지 않아, 새로운 검출/회복 메커니즘이 요구된다. 본 고에서는 AOTN에서 발생 가능한 공격 유형을 광소자별로 분석하고, 광 레벨에서의 공격 검출과 회복 메커니즘을 소개한다. 이를 바탕으로 공격관리 시스템(Attack Management System: AMS)의 제어 모델을 기술한다.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.11a
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• pp.224-227
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• 2005

KSL V-I 2단 탑재대를 복합재료 샌드위치 구조물로 설계/제작하였다. 축소형 탑재대를 제작하여 진동 특성을 측정하고, 측정된 결과를 이용하여 실물형 탑재대를 설계하였다. 탑재물의 중량을 포함하여 1차 고유진동수가 150 Hz가 되도록 설계하였으며 실제 시제를 제작하여 동특성을 측정하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.12
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• pp.1483-1487
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• 2013

Water injection pump outputs oil with high pressure during this process, seawater is injected into the well to recover the well pressure and maintain high productivity. A water injection pump has high productivity, and therefore, it serves as a key piece of equipment in marine plants. In this light, water injection pumps are being studied widely in industry. In this study, the rotor dynamics is analyzed to determine the natural frequency according to the bearing stiffness and operation speed change. This study aims to establish the pump reliability through critical speed, stability, and unbalance response analysis.

• The Journal of Korean Society for School & Community Health Education
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• v.13 no.2
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• pp.77-91
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• 2012

배경 및 목적: 성병 감염, 조기 성경험, 다수의 성관계 파트너 등과 같은 위험 성행동은 여성의 건강 전반을 위협하는 결과를 초래할 수 있다. 하지만, 이러한 심각성에 비하여, 미국의 청소년기 및 청년기 여성의 위험 성행동을 소수인종 집단별 특성을 고려한 연구는 부족한 실정이다. 그러므로 본 연구는 미국 소수인종 여성 청소년의 위험 성행동에 대한 실태를 조사하고자 한다. 방법: 본 연구는 2차 자료 분석의 결과물로써, 원자료인 미국의 National Longitudinal Study of Adolescent Health (Add Health)의 1기 (1995년)와 3기 (2001년)의 자료 중 여성 청소년의 자료를 바탕으로 분석되었다. 다양한 위험 성행동을 인종별로 분석함과 더불어 본 연구의 특징은 종단적 성병 감염 행태를 인종별로 분석한 점이다. 결과: 본 연구는 소수인종 여성의 위험 성행동에 관한 핵심적인 결과를 제시한다. 성병 감염, 조기 성경험, 다수의 성관계 파트너 등과 같은 위험 성행동의 분포는 흑인과 아시아계 여성이 타인종의 여성에 비하여 높은 위험해 쳐해 있는 것으로 나타났다. 본 연구의 흑인 여성들은 전반적인 성행동을 망라하여 고위험군으로 분류되고 있다. 아시아계 여성 역시 고위험 군으로 분류되는데, 특히, 청소년기에 성병에 한번 감염된 경험이 있는 아시아계 여성은 가장 위험한 성병 감염 행태를 보이고 있는 것으로 나타났다. 결론: 본 연구의 결과는 소수인종 여성의 위험 성행동이 백인보다 전반적으로 높은 편으로 나타나지만, 적절한 보건의료 서비스에서는 소외되는 현실을 지적하고 있다. 이러한 인종별 성건강의 불균형 문제해소를 위하여 청소년들에게 인종적 특성과 서비스 접근성의 고려가 절실히 필요하다고 사료된다.

• Proceedings of the SAREK Conference
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• 2006.06a
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• pp.927-932
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• 2006

A simulation and experimental study for energy flow dynamics of floor radiant heating system were performed. The study was done under both environmental chamber and a house with several rooms. The unsteady energy analysis method using equivalent R-C circuit and radiation heat transfer analysis of enclosure analysis method with simple structured rooms were used for computer simulation. Also, first order dynamics with time delay in analyzing the return water was considered. The results of temperature changes of the simulation study are good fit with the ones of experimental one.

• Journal of the Korean Institute of Navigation
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• v.25 no.1
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• pp.45-52
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• 2001

The purpose of this study is the optimum modification of dynamic characteristics of stiffened plate structure. In the method of the optimization, finite element method(FEM), sensitivity analysis and optimum structural modification method are used. To begin with, using FEM, the dynamic characteristics of stiffened plate structure is analyzed. Next, rate of change of dynamic characteristics by the change of design variable is calculated using the sensitivity analysis. Then, amount of change of design variable is calculated using this sensitivity value and optimum structural modification method. The change of natural frequency is made to be an objective function. Thickness of plate and cross section moment become a design variable. It is shown that the results are effective in the optimum modification for dynamic characteristics of the stiffened plate structure.

• Journal of the Korean Institute of Telematics and Electronics
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• v.9 no.1
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• pp.1-6
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• 1972

The ftatistica1 correlation method for estimating impulse response using maximum period null sequence as test signal was studied and in describing some preliminary experimental work, the author discussed the problms of mechanization supported by analytical considerations. Experiments were performed on the 2nd order oscillatory system and the results were in good coincidence with the theoretical values.

• Korean Journal of Environmental Biology
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• v.34 no.3
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• pp.151-160
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• 2016

To understand size fractioned chlorophyll a and material cycles of coastal ecosystem in Uljin marine ranching area (JMRA) of East Sea, 4 times of survey were conducted from April to November 2008. Picoplankton, nanoplankton and netplankton in the surface of UMRA fluctuated with an annual mean of $0.26{\mu}g\;L^{-1}$ between the lowest value of $0.03{\mu}g\;L^{-1}$ and the highest value of $0.87{\mu}g\;L^{-1}$, annual mean $1.32{\mu}g\;L^{-1}$ between $0.11{\mu}g\;L^{-1}$ and $5.60{\mu}g\;L^{-1}$, annual mean $0.45{\mu}g\;L^{-1}$ between no detected (nd) and $4.68{\mu}g\;L^{-1}$, respectively. And the relative ratio of picoplankton, nanoplankton and netplanktons on the phytoplankton biomass was on annual average 12.9%, 65.0% and 22.1%, respectively. The 10 m layer was similar to the surface. The relative ratio of pico- and nano-plankton was higher throughout the year. That is, the material cycle of UMRA consists of a microbial food web rather than traditional food chain at a lower trophic levels. Primary production is deemed to have a higher possibility of being adjusted by top-down dynamics, such as micro-zooplankton grazing pressure rather than nutrients supply.

• Korean Journal of Ecology and Environment
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• v.54 no.2
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• pp.79-86
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• 2021

In this study, the distribution and habitat characteristics of Odontobutis obscura were investigated. It is a freshwater fish species which belongs to the Class I Endangered species as specified by the Ministry of Environment of South Korea. Sampling was conducted in the Sanyang Stream watershed between April and August of 2016. The Sanyang Stream watershed includes the Sanyang and Gucheon Streams, and their tributaries. Odontobutis obscura was caught at every sampling site, except sites 1~3, which are located in the lower part of the Sanyang Stream. Its habitat range extended from the headwaters to the lower parts of the stream that were not impacted by the South Sea. Salinity was the major factor limiting the distribution of O. obscura in the Sanyang Stream watershed. All individuals of O. obscura were caught in areas where the substrate composition was over 50% gravel. Furthermore, the substrate composition seems to be the most important habitat factor affecting spawning of O. obscura. Ecological studies of O. obscura are scarce, and this study is the first to report a detailed distribution for the species. Further studies on the physiology and ecology of O. obscura are essential for establishing preservation strategies for this endangered species.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.9
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• pp.643-651
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• 2020

A capsule train runs inside a sub-vacuum tube and can reach very high speed due to the low air resistance. A capsule train uses a superconducting electrodynamic suspension (SC-EDS) method for levitation, which allows for a large levitation gap and does not require gap control. However, SC-EDS has inherent characteristics such as the large gap variation and a small damping effect in the levitation force, which can degrade the running stability and ride comfort. To overcome this, a stability improvement device should be designed and applied based on dynamic analysis. In this study, a 1/10 small-scale testbed was developed to replicate the dynamic characteristics of a capsule train and investigate the performance of stability improvement devices. The testbed is composed of a 6-degree-of-freedom Stewart platform for the realization of bogie motion, a secondary suspension with a running stabilization device, and a carbody. Based on the dynamic similarity law proposed by Jaschinski, the small-scale testbed was manufactured, and a bogie motion algorithm was applied with the consideration of guideway irregularity and levitation stiffness. The experimental results from the testbed were compared with simulation results to investigate the performance of the testbed.