• 한국의학물리학회지:의학물리
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• 제28권3호
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• pp.111-121
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• 2017

Verification of dose distribution is an essential part of ensuring the treatment planning system's (TPS) calculated dose will achieve the desired outcome in radiation therapy. Each measurement have uncertainty associated with it. It is desirable to reduce the measurement uncertainty. A best approach is to reduce the uncertainty associated with each step of the process to keep the total uncertainty under acceptable limits. Point dose patient specific quality assurance (QA) is recommended by American Association of Medical Physicists (AAPM) and European Society for Radiotherapy and Oncology (ESTRO) for all the complex radiation therapy treatment techniques. Relative and absolute point dose measurement methods are used to verify the TPS computed dose. Relative and absolute point dose measurement techniques have a number of steps to measure the point dose which includes chamber cross calibration, electrometer reading, chamber calibration coefficient, beam quality correction factor, reference conditions, influences quantities, machine stability, nominal calibration factor (for relative method) and absolute dose calibration of machine. Keeping these parameters in mind, the estimated relative percentage uncertainty associated with the absolute point dose measurement is 2.1% (k=1). On the other hand, the relative percentage uncertainty associated with the relative point dose verification method is estimated to 1.0% (k=1). To compare both point dose measurement methods, 13 head and neck (H&N) IMRT patients were selected. A point dose for each patient was measured with both methods. The average percentage difference between TPS computed dose and measured absolute relative point dose was 1.4% and 1% respectively. The results of this comparative study show that while choosing the relative or absolute point dose measurement technique, both techniques can produce similar results for H&N IMRT treatment plans. There is no statistically significant difference between both point dose verification methods based upon the t-test for comparing two means.

• 대한기계학회논문집A
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• 제39권3호
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• pp.275-282
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• 2015

최근 전투에서 인명 손실을 최소화하기 위해 사람이 접근하기 어려운 지역에서 부상병을 구조해내는 로봇(Vecna Bear type robot)이 개발되고 있다. Vecna BEAR 형 로봇은 험한 지형을 주행하게 되므로 큰 진동 및 전복에 의해 부상자에게 충격을 가할 수 있다. 이러한 로봇의 안정성을 보장하기 위해서는 다양한 환경에 대해 주행 한계속도를 실시간으로 추정할 수 있는 알고리즘이 요구된다. 따라서 한계속 도추정 알고리즘을 수행하기 위하여 실시간 해석이 가능한 동역학 모델이 필요하다. Vecna BEAR 형 로봇의 구동부인 궤도는 실제로 많은 요소로 구성되어 있기 때문에 궤도의 다물체 동역학 모델에 의한 실시간 해석은 불가능하다. 그러므로 적은 해석량과 합당한 정확성을 만족하는 lumped 궤도 모델이 필요하다. 본 연구에서는 이러한 lumped 궤도 모델링을 수행하였고, 다물체 동역학 상용 프로그램인 RecurDyn 을 이용하여 견인력을 검증하였다.

• 터널과지하공간
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• 제28권5호
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• pp.493-511
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• 2018

본 논문에서는 그라운드 앵커의 긴장력 손실에 대응하고자 긴장력 상시확인을 위한 앵커 긴장력 상시 육안확인장치에 대한 내용을 다루었다. 그라운드 앵커는 사회적 인프라 시설의 안정성을 확보하기 위해 시공되었지만 지속적인 긴장력 손실로 인해 시설물에 대한 안전이 심각하게 우려되고 있는 실정이다. 이에 앵커의 유지관리가 요구되지만 현재 잔존긴장력의 계측은 경제적인 측면을 고려하여 표본조사로 이루어지고 있어 정밀도에 대한 한계점을 지니고 있다. 따라서 본 논문에서는 앵커의 긴장력을 육안으로 확인할 수 있는 앵커 긴장력 상시 육안확인장치의 개발을 목적으로 개념설계, 실내 인장실험을 통한 규격화를 수행하였으며, 현장시험을 통해 성능을 확인하였다.

• Journal of Advanced Marine Engineering and Technology
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• 제26권3호
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• pp.299-306
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• 2002

The load frequency control(LFC) of power system is one of important subjects in view of system operation and control. That is, even though the rapid load disturbances are applied to the given power system, the stable and reliable power should be supplied to the users, converging unconditionally and rapidly the frequency deviations and the tie-line power flow ones of each area into allowable boundary limits. Nonetheless of such needs, if the internal parameter perturbation and the sudden load variation are given, the unstable phenomena of power systems can be often brought out because of the large frequency deviation and the unsuppressible power line one. So, an optimal modulation controller for UC of multi-area power system is designed by a recursive algorithm that determines the state weighting matrix Q of a linear quadratic performance criterion. The optimal modulation controller is based on optimal control and can obtain the exact dynamic response of the UC of multi-area power system in the time domain. The performances of the resultant optimal modulation control, that is, the steady-state deviations of frequency and tie-line power flow and the related dynamics, were investigated and analyzed in detail by being applied to the UC of multi-area power system in the perturbations of predetermined internal parameters. Through the simulation results tried variously in this paper for disturbance of stepwise load changes, the superiorities of the proposed optimal modulation controller in robustness and stability were proved.

• 한국연소학회지
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• 제18권4호
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• pp.29-36
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• 2013

Numerical study was conducted to clarify effects of added $CO_2$ for the downstream interaction between $H_2$-air and CO-air premixed flames in counterflow configuration. The reaction mechanism adopted was Davis model which had been known to be well in agreement with reliable experimental data. The results showed that both lean and rich flammable limits were reduced. The most discernible difference between the two with and without having $CO_2$ addition into $H_2$-air and CO-air premixtures was two flammable islands for the former and one island for the latter at high strain flame conditions. Even a small amount of $H_2$, in which $H_2$-air premixed flame cannot be sustained by itself, participates in CO oxidation, thereby altering the CO-oxidation reaction path from the main reaction route $CO+O_2{\rightarrow}CO_2+O$ with a very long chemical time in CO-air flame to the (H, O, OH)-related reaction routes including $CO+OH{\rightarrow}CO_2+H$ with relatively short chemical times. This intrinsic nature alters flame stability maps appreciably. The results also showed that chemical effects of added $CO_2$ suppressed flame stabilization. Particularly this phenomenon was appreciable at flame conditions which lean and rich extinction boundary was merged. The detailed discussion of chemical effects of added $CO_2$ was addressed to the present downstream interaction.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 추계학술대회 논문집 전력기술부문
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• pp.46-48
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• 2005

This paper discusses a probabilistic method for power system security assessment. The security analysis relates to the ability of the electric power systems to survive sudden disturbances such as electric short circuits or unanticipated loss of system elements. It consists of both steady state and dynamic security analyses, which are not two separate issues but should be considered together. In steady state security analysis including voltage security analysis, the analysis checks that the system is operated within security limits by OPF (optimal power flow) after the transition to a new operating point. Until now, many utilities have difficulty in including dynamic aspects due to computational capabilities. On the other hand. dynamic security analysis is required to ensure that the transition may lead to an acceptable operating condition. Transient stability, which is the ability of power systems to maintain synchronism when subjected to a large disturbance. is a principal component in dynamic security analysis. Usually any loss of synchronism may cause additional outages and make the present steady state analysis of the post-contingency condition inadequate for unstable cases. This is the reason for the need of dynamic studies in power systems. Probabilistic criterion can be used to recognize the probabilistic nature of system components while considering system security. In this approach. we do not have to assign any predetermined margin of safety. A comprehensive conceptual framework for probabilistic static and dynamic assessment is presented in this paper. The simulation results of the Western System Coordinating Council (WSCC) system compare an analytical method with Monte-Carlo simulation (MCS).

• Bulletin of the Korean Chemical Society
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• 제32권8호
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• pp.2771-2775
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• 2011

Poly-ethylenedioxypyrrole (PEDOP) coated thiolated multiwall carbon nanotubes palladium nanoparticles (MWCNTs-Pd) modified glassy carbon electrode (GCE) [PEDOP/MWCNTs-Pd/GCE] for the determination of hydroquinone (HQ) and it’s isomer catechol (CA) were synthesized and compared with bare GCE and thiolated multiwall carbon nanotubes (MWCNTs-SH/GCE). The modification could be made by simple processes on a GCE with MWCNTs-Pd covered by PEDOP in a 0.05 M tetrabutylammonium perchlorate (TBAP)/MeCN solution system. A well-defined peak potential evaluation of the oxidation of hydroquinone to quinone at 0.05 V (vs. Ag/AgCl), and electrochemical reduction back to hydroquinone were found by cyclic voltammetry (CV) in phosphate buffered saline (PBS) at pH 7.4. Peak current values increased linearly with increasing hydroquinone contents. The peak separation between the anodic and cathodic peaks at the PEDOP/MWCNTs-Pd/GCE was ${\Delta}Ep$ = 40 mV for HQ and ${\Delta}Ep$ = 70 mV for CA, resulting in a higher electron transfer rate. Moreover, good reproducibility, excellent storage stability, a wide linear range (0.1 ${\mu}M$ - 5 mM for HQ and 0.01 ${\mu}M$ - 6 mM for CA), and low detection limits ($2.9{\times}10^{-8}$ M for HQ and $2.6{\times}10^{-8}$ M for CA; S/N = 3) were determined using differential pulse voltammetry (DPV) and amperometric responses; this makes it a promising candidate as a sensor for determination of HQ and CA.

• 항공우주정책ㆍ법학회지
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• 제14권
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• pp.151-174
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• 2001

Theories of international organization have explained the creation, maintenance, and decline of international organization. However, their explanations on changes of international organization have been much more different one another. For example, the theory of hegemonic stability argues that international organization can be created and maintained only by a hegemonic state and will be declined if the hegemonic state decline. On the other hand, the functional approach believes that the positive functions and effects that international organization provides motivate states to create and maintain the organization, while the game-theoretical approach explains international organization based on cost-benefit calculation of rational states. Thus, the empirical evaluation of the arguments of the theories of international organization and defining the major factors that determine international organization are necessary not only for the development of theories of international organization but also for making desirable policies toward international organization. For the purpose, this paper compares and contrasts the three major theories of international organization and applies the approaches to the case of the International Civil Aviation Organization (ICAO) to test their arguments. Since the ICAO has been rarely examined by the theories of international organization, the case study could be desirable case to evaluate theories of international organization. In this sense, this paper attempts to define the major factors that determine the creation, maintenance, and decline of the ICAO. In particular, since the Korean government has changed its policy for air transport security system recently, it will investigate the role of ICAO on the policy change to define the limits and strength of ICAO. In conclusion, this paper will assess the relative explanatory power of each approach based on the analysis of the creation and changes of ICAO

• 한국융합학회논문지
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• 제11권1호
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• pp.57-63
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• 2020

본 연구는 수동진동을 융합한 슬링운동이 뇌졸중환자의 균형과 보행에 미치는 영향을 알아보는데 목적이 있다. 1회 35분 주3회 6준간 실시하였다. 슬링운동 실험군과 대조군 각각 8명으로 나누었다. 균형과 보행을 측정하였다. 실험군과 대조군의 중재 후 군간 비교에서 눈 뜨고 서기와 눈 감고 서기는 유의한 차이가 나타났다. 실험군과 대조군 모두 중재 전후 눈 뜨고 서기, 눈 감고 서기, 안정성 한계, 보행 속도에서 군내 유의한 차이가 나타났다. 진동슬링 운동이 뇌졸중 환자의 균형과 보행을 증진시키는데 도움을 줄 수 있다고 사료된다. 향후 많은 대상자와 다양한 주파수, 효과적인 운동기간에 대한 연구가 필요하다.

• 대한치과의사협회지
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• 제53권9호
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• pp.602-609
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• 2015

The aim of this document is to evaluate the effect of bite balance on physical fitness and motor capacity to determine the importance of the occlusal stability as a possible action mechanism of occlusal appliance including mouthguards on physical performances. We all remember that day when the prominent athlete was in the news wearing a mouthguard to improve human athletic performance. I once had investigated the determinants of athletic performance in all sorts of sports. Most of the studies had overinterpretation of results and lack of evidence to support the information. However, I discovered great expectations for new possibility in this field and settled for a more academic approach to this intriguing subject. The followings are some examples of the subject 1. Archers who wore occlusal appliances to increase the vertical dimension of occlusion by 2~3mm increased their ability to focus and to maintain good sense of balance. Their accuracy rate has been improved. The appliance was made of acrylic resin (a type of plastic). 2. Canoe players who wore occlusal appliances to increase the vertical dimension of occlusion by 5mm surpassed longtime competitor and won the race with 10 seconds gap. 3. A cycle rider who wore an occlusal appliance to treat his malocclusion surpassed his old record from 10.8 seconds to 10.3 seconds. His muscle reflexes (anaerobic exercise) and endurance (aerobic exercise) has been enhanced. 4. Occlusal appliances had a good effect on athletic performance in most sports such as swimming, diving, and weightlifting. As for the clenching on dentition, people clench their teeth when they push their physical and mental limits during sports activities. Clenching can be induced by physical exertion when maximum muscle strength is retained and this is similarly found in different types of exercises. In addition, restraint of respiratory function is observed. Therefore, creating a occlusal balance with occlusal appliance or mouthguard promoted a favorable influence when an athlete clenches.