• 대한물리치료과학회지
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• 제16권4호
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• pp.67-74
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• 2009

Background: This study had been carried out with 20 elderly subjects as its object for about one month from November 3, 2008 to December 14, 2008 in order to observe the effect of Underwater Treadmill on the elderly's walking and balance ability. Methods: Subjects were assigned either experimental group (n=10) or the control group (n=10), experimental group received Underwater Treadmill program (30 min per course, 3days a week for 6weeks). Subjects were assessed for muscle power (Nicolas Manual Muscle Test), balance (Functional Reach Test), gait ability (Time Up and Go, 10M walking test) before experiments and after experiments. Results: The results of this study were as follows; 1. After underwater treadmill exercise, the change of isometric contraction indicated a beneficial increase on lower extremity muscle power of experimental group and functional test of balance function; FRT, TUG indicated beneficial difference between groups. 2. beneficial difference between groups in walking speed of hourly index change of walking function. 3. between muscle power and balance, gait ability, we could find out there's high correlation ship between lower extremity muscle power increasing and balance and gait ability of the elderly. Conclusion: Aerobic exercise using underwater treadmill effects on muscle power strengthening of the elderly, and because of this, increase of lower extremity muscle power is very helpful not only to improvement of balance ability, but also to improvement of gait ability, so it will be used as a physical therapy program on clinic and used as an exercise program for protecting the elderly from falling down very well.

• 해양안보
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• 제3권1호
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• pp.73-114
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• 2021

본 연구는 현실주의의 대표적 이론인 세력균형이론을 기초로 군사력을 국가의 핵심 힘으로 전제하여 동북아시아의 힘의 분포를 살펴본다. 이전 세력균형과 군사력 수준에 관한 연구결과를 고찰하고, 그 연구한 결과를 활용하여 2020년까지 미국, 중국, 러시아, 일본, 한국과 북한의 힘의 변화를 분석하여 2030년경 안보환경을 전망하여 본다. 세력균형이론에서 국가(nation)나 국가군(a group of power) 간에 힘의 균형이 무너지면 전쟁 가능성이 높고, 그 불확실성과 불신이 높은 국제사회에서 생존과 안전을 확보하기 위하여 국가는 힘의 증강(자조, self-help)과 더불어 협력(cooperation)과 동맹(alliance)을 더욱 강화하는 행동을 한다고 본다. 동북아시아의 국가들도 자국의 군사력을 지속 증강하고 있으며, 특히 중국의 급속한 부상으로 국제 안보환경의 급격한 변화에 주변 국가들은 촉각을 세우고 경계심을 늦추지 않고 있다. 중국은 2030년대 중국 창군 100주년과 더불어 '국방 및 군현대화'를 실현하고, 2050년대 건국 100주년에 '세계일류군대건설'을 목표로 하고 있다. 그리고 미국은 국제사회의 협력과 동맹 강화 등 중국 견제에 분주하다. 미국과 중국이 패권경쟁이 진행되고 있는 상황에서 동북아시아의 안보환경과 힘의 역학관계도 서서히 변하고 있다. 세력균형이론에 기초하여 2030년 이후 동북아시아의 힘의 분포 변화와 함의를 살펴보고자 한다.

• International journal of advanced smart convergence
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• 제11권4호
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• pp.216-226
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• 2022

In this study, we selected and trained 9 people in the diaphragm training group and 9 people in the power-breath training group among elderly people aged 65 or older living in the community, and investigated the effect of combined training using respiratory equipment on lung function, balance, and life satisfaction. We conducted the elderly to do combined exercises, twice a week for a total of 6 weeks, that include the breathing training by diaphragm, the breathing training using Power-breath equipment, and the training using a theraband. We evaluated the changes in the lung function, the balance, and the life satisfaction before and after the intervention for our study subjects.As a result of our measurement, lung function, balance, and life satisfaction showed significant changes in the experimental group that performed the combined training using Power-breath equipment. As a result of the study, we confirmed that the elderly in the community had a positive effect on the life satisfaction by improving lung function and balance ability after conducting a combined training using respiratory equipment.

• Journal of Power Electronics
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• 제16권6호
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• pp.2109-2118
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• 2016

Based on the space vector pulse width modulation (SVPWM) theory, this paper realizes an easier SVPWM strategy, which is equivalently implemented by CBSPWM with zero-sequence voltage injection. The traditional SVPWM strategy has no effect on controlling the neutral-point voltage balance. In order to solve the neutral-point voltage unbalance problem for neutral-point-clamped (NPC) three-level inverters, this paper proposes a neutral-point voltage balance controller. The proposed controller realizes controlling the neutral-point voltage balance by dynamically calculating the offset superimposed to the three-phase modulation waves of an equivalent SVPWM strategy. Compared with the traditional SVPWM strategy, the proposed neutral-point voltage balance controller has a strong ability to balance the neutral-point voltage, has good steady-state performance, improves the output waveforms quality and is easy for digital implementation. An experiment has been carried out on a NPC three-level inverter prototype based on a digital signal processor-complex programmable logic device (DSP-CPLD). The obtained experimental results verify the effectiveness of the proposed neutral-point voltage balance controller.

• 한국항공우주학회지
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• 제35권9호
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• pp.850-857
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• 2007

인공위성 전력계의 설계 분석은 위성 전체의 무게, 크기 및 성능을 결정하는 중요 변수로 작용한다. 특히 위성체 에너지 균형 분석의 경우 전력 시스템의 용량, 설계 제한 조건의 결정 및 위성체 운영 성공 여부를 결정할 수 있는 중요한 분석이다. 본 논문에서는 저궤도 위성 개발을 위한 새로운 에너지 균형 분석 프로그램을 소개하고 타 저궤도 위성 설계 자료를 이용한 시험 결과를 일례로 기술하였다. 시험 결과 본 논문에서 제안한 에너지 균형 분석 프로그램은 위성체 전력계의 최적 사이징 뿐 아니라 위성체 운영 기간 동안 궤도상에서의 위성체 에너지 균형 상황 예측에도 활용할 수 있음을 보였다.

• Journal of Power Electronics
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• 제12권1호
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• pp.88-97
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• 2012

This paper presents a method for the digital control of a high power factor AC/DC converter employing the power balance control technique to achieve a fast response of the output voltage control. To avoid the effects of an output voltage ripple in the voltage control loop, the average output voltage is sampled and used as a feedback signal for the output voltage controller. The proposed control technique was verified by simulations using MATLAB/Simulink and its implementation was realized by a dsPIC30F4011 digital signal processor to control a CUK topology AC/DC converter with a 48V output voltage and a 250 W output power. The experimental results agree with the simulation results. The proposed control technique achieves a fast transient response with a lower line current distortion than is achieved when using a conventional proportional-integral controller and the power balance control technique with the conventional sampling method.

• 대한기계학회논문집A
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• 제26권8호
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• pp.1585-1590
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• 2002

This paper reports on the balance weight effect on the lubrication and friction characteristics of crankshaft system. To determine the main bearing loads, the crankshaft was treated as statically determinate system. Four and eight-balance weight crankshafts were considered, and minimum oil film thickness and friction loss were calculated. The main bearing loads were increased in the four-balance shaft due to the increasing of unbalanced rotating mass at No. 1 and 3 main bearing sides. The minimum oil film thickness of four-balance shaft became thinner than eight-balance, and friction loss was increased.

• 전자공학회논문지
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• 제50권1호
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• pp.117-123
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• 2013

본 논문은 symmetric balance incomplete block design(BIBD) code의 BER=$10^{-9}$을 만족하는 spectral efficiency를 구하였다. 이 계산 결과 effective power가 큰 경우 ($P_{sr}=-10$ dBm)는 m=2로 고정시키고 q값을 변화시키는 ideal BIBD code구성이 효율적이었다. 이와 반대로 effective power가 작은 경우 ($P_{sr}=-25$ dBm)는 ideal BIBD code 구성 보다는 q > 2인 값을 취하고 m값을 변화시키는 설계가 더 효율적임을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제50권5호
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• pp.648-653
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• 2018

Elimination of soluble boron from reactor design eliminates boron-induced reactivity accidents and leads to a more negative moderator temperature coefficient. However, a large negative moderator temperature coefficient can lead to large reactivity feedback that could allow the reactor to return to power when it cools down from hot full power to cold zero power. In soluble boron-free small modular reactor (SMR) design, only control rods are available to control such rapid core transient. The purpose of this study is to investigate whether an SMR would have enough control rod worth to compensate for large reactivity feedback. The investigation begins with classification of reactivity and completes an analysis of the reactivity balance in each reactor state for the SMR model. The control rod worth requirement obtained from the reactivity balance is a minimum control rod worth to maintain the reactor critical during the whole cycle. The minimum available rod worth must be larger than the control rod worth requirement to manipulate the reactor safely in each reactor state. It is found that the SMR does have enough control rod worth available during rapid transient to maintain the SMR at subcritical below k-effectives of 0.99 for both hot zero power and cold zero power.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.307-308
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• 2009