• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2011년도 한국우주과학회보 제20권1호
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• pp.31.1-31.1
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• 2011

In this study, we investigated alignment state estimation performances of the three methods i.e. merit function regression (MFR), differential wavefront sampling (DWS) and Multiple Design Configuration Optimization (MDCO). The three target optical systems are 1) a two-mirror Cassegrain system for deep space Earth observation, 2) intermediate size three-mirror anastigmat for Earth ocean monitoring, and 3) extremely large segmented optical system for astronomical observation. We ran alignment state estimation simulation for several alignment perturbation cases including 1mm to 10mm in decenter and from 0.1 to 1 degree in tilt perturbation error for the two-mirror Cassegrain system. In general, we note that MDCO shows more competitive estimation performance than MFR and DWS. The computational concept, case definition and the simulation results are discussed with implications to future works.

• 전기학회논문지
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• 제61권10호
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• pp.1536-1541
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• 2012

The study analyzed problems by iron core structure of the three phased transformer on asymmetric three phase lines, which included line disconnections, ground faults, COS OFF, and unbalanced loads on the power distribution system. In particular, by analyzing PT combustion cases within the MOF, the study was able to analyze the combustion cause of the core-type transformer and its effect on the system, conduct simulations and practice demonstrations on the characteristics for each iron core structure of the three phase transformer using PSCAD/EMTDC, and suggest measures to prevent the combustion of the core-type transformer.

• 한국산학기술학회논문지
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• 제10권2호
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• pp.388-395
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• 2009

2006년에 공개키 연산 대신 XOR 연산과 해쉬함수만을 사용하는 스마트카드를 이용하는 3자 참여 인증된 키 교환 프로토콜이 제안되었다. 최근에는 개인프라이버시에 대한 관심이 높아지며 사용자 익명성을 보호하기 위한 연구가 진행되고 있다. 본 논문에서는 2006년 제안된 3자 참여 인증된 키 교환 프로토콜이 사용자 익명성을 제공하지 못하며 잘못된 입력값 감지가 늦다는 문제점을 제기하고, 이러한 문제점을 해결하기 위해서 스마트카드 기반 3자 참여 키 교환 프로토콜을 제안하였다.

• 한국기계가공학회지
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• 제11권1호
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• pp.107-112
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• 2012

Air flow and its pressure at electric fan according to three, four and five blades are analyzed in this study. As the number of blades increases at the same condition of specification, air tends to converge and becomes natural wind but higher power is consumed. And the velocity of wind is decreased as the space between winds becomes narrow. The turbulent flow is happened in the center of the body of revolution and the kinetic energy becomes largest in case of three blades. The pressure is decreased than atmospheric pressure from fan to outlet. As the number of blades increases, the pressure drop becomes smaller and is smallest in case of the fan with three blades. As the study result, The electric fan with three blades is thought to be effective in view of power consumption and design.

• 대한족부족관절학회지
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• 제4권1호
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• pp.48-54
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• 2000

Haglund's syndrome produces retrocalcaneal bursitis or achilles tendinitis due to impingement of posterior superior bursal projection of calcaneus on insertional fibers of achilles tendon. Haglund's syndrome has been mainly associated with wearing rigid counter shoes and with athletes. We experienced three case of late sequelae of secondary Haglund's syndrome after malunion of tongue type calcaneus fracture. It is to be the first description of secondary Haglund's syndrome after calcaneus malunion and also the first report as the late complication of calcaneus fractures. Three cases were all tongue type intraarticular fractures and were treated with $45^{\circ}$ superior angle resection of superior calcaneal tuberosity. Clinical results by modified Rowe score were excellent with complete pain relief for all three cases.

• Korean Journal of Acupuncture
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• 제28권4호
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• pp.159-167
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• 2011

Objectives : This study was performed to find a desirable way for acupuncture treatment of Alzheimer Disease. Methods : The authors reviewed several literatures about 'Alzheimer Disease' and 'Dementia'. Based on the review, we interpreted the causes and symptoms on viewpoint of three yin and three yang, and also researched desirable way for acupuncture treatment of Alzheimer Disease. Results and Conclusions : The symptoms of Alzheimer Disease belong to the unbalance between reverting yin and lesser yang. The factors affecting attack rate of Alzheimer Disease are also related with the unbalance between reverting yin and lesser yang. It is necessary to inhibit the function of reverting yin and to activate the function of lesser yang for the acupuncture treatment of Alzheimer Disease.

• KIEAE Journal
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• 제4권4호
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• pp.53-60
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• 2004

This study is to set up some models and make plans of the seaside resorts at coastal area in Korea. In order to do this we analyse the characteristics of east, south and west coastal areas of Korean peninsula. And we divide coastal areas into three categories, such as suburban area, fishing village area, and island area, according to their development phases and the distances from nearby big cities. Three types of seaside resort model for three categories of coastal areas are set up. At last we make site plans and images of three types of seaside resort model.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권11호
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• pp.505-513
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• 2001

This paper presents the new three-level optimal control scheme for the large scale nonlinear systems, which is based on fast walsh transform. It is well known that optimization for nonlinear systems leads to the resolution of a nonlinear two point boundary value problem which always requires a numerical iterative technique for their solution. However, Three-level costate coordination can avoid two point boundary condition in subsystem. But this method also has the defect that must solve high order differential equation in intermediate level. The proposed method makes use of fast walsh transform, therefore, is simple in computation because of solving algebra equation instead of differential equation.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.274-276
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• 2001

A simple current controller for three-phase PWM power inverters using 3-level comparator is presented. All voltage vectors are accurately selected in order to minimize the current error using two three-level comparators and ${\alpha}-{\beta}$ current reference frame. The proposed algorithm have fast response and low current errors. This current controller is improved synchronization problem and increased the voltage utilization value. Usefulness of propose method are verified on the simulation result using Matlab/Simulink.

• Journal of Plant Biology
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• 제22권4호
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• pp.141-145
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• 1979

Phytoplanktons and environmental conditions in the Geum River near Gongju were investigated at three stations in July, 1979. Fifty eight kinds of hytoplanktons were identified and of these, Cyanophyta and Chlorophyta in this area appeared more in the number of species than that in the Han River. The number of species of Chlorophyta was double or more at station 2 and station 3 which were situated near Gongju than at station 1, upperstream of Gongju and the number of species of phytoplankton was also higher at station 2 and station 3 than at station 1. In physicochemcial conditons, water temperature at all of three stations was lower than air temperature and pH might have no significance among these three stations. All of these three stations were characterized as the slower flowing water type of downstream in diatom river community.