• Korean Journal of Applied Biomechanics
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• v.19 no.4
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• pp.689-696
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• 2009

This study was conducted to examine the effects of the lumbar stabilization exercise (LSE) on fall prevention in elderly females (n = 21) by measuring changes in the isometric strength, multifidus, transverse abdominis muscle thickness, and posture stability index. The strength of isometric contraction was measured by the 3-D Pegasus system ; the thickness of the multifidus and transverse abdominis were measured by using Sonoace 6000C, and the posture stability index was measured using a computerized Biodex Balance System SD apparatus analysis. These results lead us to the conclusion that flexion and extension, left rotation on strength of isometric contraction, and thickness of the transverse abdominis (when released) statically increased. Overall, the anterior/posterior and medial/lateral elements in the posture stability index statically decreased, Consequently, the LSE should the prevent falls in elderly females.

• Information and Communications Magazine
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• v.33 no.9
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• pp.24-29
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• 2016

영상의 화질 개선과 높은 대비를 얻기 위한 방법으로 최근 HDR(High Dynamic Range)영상을 디스플레이 장치에 매핑시키기 위한 톤매핑 기술이 널리 이용되고 있다. 하지만 단일프레임이 아닌 다중프레임으로 구성되어 있는 비디오에 이러한 톤매핑기술을 적용할 경우, 프레임 간 명암도 차이로 인하여 시각적으로 깜빡이는 현상인 플리커(Flicker)가 발생할 수 있으며, 이로 인해 사용자의 눈에 피로도를 증가시키고, 영상의 품질이 감소할 수 있다. 본 논문에서는 플리커 판별을 위해 영상의 명암도 측정법을 제안하여, 프레임별 명암값을 학습하기 위한 다양한 특징벡터를 정의한다. 학습된 SVM(Support Vector Machine) 분류기를 이용하여 플리커 발생 프레임을 선별하고 플리커 제거를 위한 톤 안정화 방법을 제안한다. 실험에서 제안한 방법을 통해 86.7%의 플리커를 검출하였으며, 프레임 간 톤 안정화 알고리즘의 최적화를 통해 플리커 발생빈도를 69.8% 감소시켰다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.186-190
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• 2011

The Line-Of-Sight stabilization system is designed to minimize the error of Line-Of-Sight under the disturbing circumstances. In order to control this system more accurately and reduce the level of the disturbance, adding an isolator is mostly considered. However, it is difficult to predict the exact the behavior of the isolator and the effect of a stabilization Error. Therefore, the simulation model of the control system using co-simulation with Adams and matlab simulink is presented and the effects of the isolation properties are reviewed.

• Proceedings of the Optical Society of Korea Conference
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• 1995.06a
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• pp.30-34
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• 1995

13C2H2분자의 1.54949$\mu$m 회전-진동 전이 흡스선을 이용하여 DFB LD의 발전주파수를 안정화 시킴으로써 이를 주파수대욕 광 다중통신(OFDM)의 표준주파수를 광동기 신호로 활용하는 방안에 대하여 연구하였다. 본 연구에서는 DFB LD의 발진주파수의 변화에 따른 기체 Cell의 투과한 빛의 세기의 변화를 연산 처리하여 이를 안정화 Loop에 대한 error 신호로 사용하여 줌으로써 MHz 이내에 주파수 안정도를 갖는 광 동기신호를 구성하였다. 이러한 안정화 방법을 이용하여 이제까지 제안된 다른 방법에 비하여 광학계통과 광신호처리 과정을 크게 단순화 된, 또한 동작중 자체 진단 및 자동복구 기능을 갖춘 이상적인 신호를 구성하였다.

• Proceedings of the KIPE Conference
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• 2011.07a
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• pp.386-387
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• 2011

본 논문은 플라즈마 방전장치 구동을 위한 가변 전압/주파수 전원장치를 제안한다. 제안하는 전원장치는 가변전압을 위한 벅-부스트 컨버터와 주파수 변환을 위한 푸쉬-풀 인버터로 구성된다. 제안하는 전원장치의 벅-부스트 컨버터는 계통전류 고조파 저감과 DC링크 캐패시터 최소화를 위하여 PFC(Power Factor Collection)기법을 적용한다. 그리고 푸쉬-풀 인버터는 출력 변압기의 자기포화를 막기 위해 전류제한기법을 추가한다. 또한 불분명한 부하와 출력 트랜스의 공진 상황에서 전압 안정화를 위해 출력전압을 피드백하여 제어한다. 본 논문은 1[kW]급 플라즈마 전원장치를 통하여 제안하는 토폴로지와 제어방법의 타당성을 검증한다.

• The korean journal of orthodontics
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• v.40 no.1
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• pp.34-39
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• 2010

Objective: The aim of the present study was to evaluate the changes in tooth mobility following orthodontic treatment and to obtain information regarding the guideline of retainer wear duration during the post-treatment period. Methods: The sample consisted of twenty patients who had been treated with edgewise appliances. The mobility of the maxillary teeth from the central incisor to the first molar was measured bilaterally by way of the $Periotest^{(R)}$, a non-invasive, electronic device that provides an objective measurement of the reaction of the periodontium to a defined impact load. Tooth mobility was monitored at the time of the removal of the orthodontic appliances and subsequently at three-month intervals during the two years following appliance removal. Results: Tooth mobility decreased rapidly for the first six months and then decreased at a slower rate during the next six months; no statistically significant decrease in mobility was observed during the second year following appliance removal. Conclusions: The results of the present study suggest that adequate tooth stabilization is critical during the first six months following appliance removal and that continued wearing of retainers is recommended at least until twelve months after the completion of orthodontic treatment.

• Korean Journal of Plant Resources
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• v.29 no.5
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• pp.579-587
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• 2016

The final goal of this research is to develop a miniaturized botanical biofilter using a wick-typed automatic humidifier for stabilizing soil moisture content (SMC) and purifying indoor air pollutants by the biofilter. This new biofilter equipped with wick-typed automatic humidifier was manufactured as more compacted design removing an absorption tower-typed humidifier compared with the previous big-sized biofilter made in 2015. This study was performed to compare changes of SMCs among floors depending on the number of wicks installed on the humidifier within the novel biofilter, and to compare changes of SMCs and plant growth parameters before and after planting Spathiphyllum wallisii ‘Mauna Loa’ on the biofilter. SMCs among floors depending on the number of wicks were similar, and all regression lines of SMCs showed almost horizontal lines because of long-term stability on SMCs. Comparing plant growth parameters of S. wallisii ‘Mauna Loa’ before planting and at 30 days after planting on the biofilter, all growth parameters were not statistically significant. Thus, SMCs of the biofilter were more stabilized using this humidifying apparatus regardless of the number of wicks than the previous biofilter using absorption tower-typed humidifying apparatus.

• Plant Journal
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• v.10 no.3
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• pp.45-51
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• 2014

This study performs several experiments on a newly developed temperature safety system that can be used for residential building heating systems, the heat source of which is derived from a conventional fuel cell. Prior to this, the hot water made from a fuel cell was not used in residential housing but just went to waste. The present safety system is installed in the current underfloor heating system. At first we used the CFD technique to develop a new heat exchanger. The fuel cell must satisfy the thermal conditions of the inlet temperature being $55^{\circ}C$ and the outlet temperature being $60^{\circ}C$. But variations in weather cause fluctuations in the heating water temperature. The experimental results show our new system capable of maintaining the temperature difference within a ${\pm}0.5^{\circ}C$ range. So we believe that our new PFMFC fuel cell stack array is a good candidate for being used in residential heating systems.

• Proceedings of the Korean Society of Crop Science Conference
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• 1995.05a
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• pp.52-53
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• 1995

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.10a
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• pp.590-593
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• 2021

본 연구에서는 목발을 사용하는 교통약자가 물품을 안정적으로 휴대할 수 있도록 도와주는 장치를 개발하였다. 2축 짐벌 구조를 기반으로 서보모터, IMU센서, 아두이노 나노 마이크로프로세서로 구현하였고, Pitch와 Roll 방향 회전을 상쇄하기 위해 센서 각도를 변환 없이 사용하는 기본제어법과 PID 제어법을 사용하여 비교하였다.