• 대한방사선치료학회지
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• 제30권1_2호
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• pp.35-40
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• 2018

목 적 : 본원에서 사용하는 양성자 에너지는 크기에 따라 도달거리가 달라지며, Compensator는 Distal 두께에 따라 Energy의 크기를 다르게 할 수 있으며 이로 인해 Dose rate이 변화된다. 따라서 Compensator distal의 두께를 변화시키면서 Dose 분포 및 Beam on time에 대한 영향을 평가해보고자 한다. 대상 및 방법 : 본원에서 양성자치료를 받은 에너지가 낮은 환자 5명을 대상으로 실험하였다. 선택된 환자들의 기존 치료 시 Beam on time을 확인하였으며 이 후 양성자치료계획시스템(TPS)을 통하여 Compensator의 Distal 두께를 기존 두께에서 2 cm씩 최대 14 cm까지 증가시켜가며 치료계획을 비교 평가하였다. Dose 분포를 평가하기 위하여 Target의 Conformity Index(CI)값과 Homogeneity Index(HI)값, Target 후면부의 Organ at risk(OAR)의 최대선량을 비교하였으며 치료시간에 대한 영향을 평가하고자 Compensator Distal 두께 별로 제작하여 Beam on time을 비교하여 평가하였다. 결 과 : Compensator의 Distal 두께를 증가시켜 Homogeneity Index, Conformity Index를 분석한 결과 모든 환자에서 동일한 수치가 나왔다. Target 후면부의 OAR을 비교한 결과 Abdomen의 Spine cord에 최대 7 cGy, Eyeball의 RT Lens에서 88 cGy, Nasal cavity의 RT Lens에 391 cGy, Mediastinum의 Trachea에 51 cGy, Pelvis의 Small bowl에 661 cGy 증가하였다. Beam on time을 비교한 결과 Abdomen의 경우 기존 126초에서 최대 62초, Eyeball의 경우 105초에서 37초, Nasal cavity의 경우 기존 187초에서 134초, Mediastinum의 경우 기존 100초에서 40초, Pelvis의 경우 기존 440초에서 118초로 감소하였다. 결 론 : 연구결과 Compensator의 distal 두께가 두꺼워질수록 에너지의 크기를 증가시킬 수 있으며 Dose rate이 증가하여 Beam on time이 감소하는 효과가 있었다. 이는 Beam on time이 많이 소요되는 호흡동조치료를 요하는 Liver, 마취를 하는 소아환자에게 적용한다면 치료시간 단축과 환자의 편의성 면에서 큰 도움을 줄 것으로 평가된다. 하지만 에너지의 크기가 증가할수록 Distal penumbra가 증가하기 때문에 Target 후면부에 OAR이 인접해 있는 경우는 양성자치료계획 시 Penumbra의 영향을 고려한 적절한 Compensator 두께를 설정할 필요가 있을 것으로 사료된다.

• 대한방사선치료학회지
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• 제1권1호
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• pp.47-51
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• 1985

Authors describe some useful data when constructing tissue-equivalent compensators which would compensate tissue deficit in the treatment field of high energy electromagnetic radiation Tissue equivalent compensator is made of lucite. The ratio of compensator thickness to the thickness of tissue deficit depends on radiation energy, field size and the distance from the compensator to patient skin. When the compensator is separated from skin surface, the thickness ratio is always smaller than 1.0. This means that the larger the separation, the contribution to the total dose by means of scattered radiation from a tissue equivalent compensator is smaller. Authors propose that the thickness of lucite as tissue equivalent compensator is 0.57 times tissue deficit and the separation between compensator and skin is at least 15m for Co-60 gamma ray and 25cm for 10MV X-ray.

• 동력기계공학회지
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• 제19권1호
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• pp.76-82
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• 2015

An analysis model is developed using a commercial software 'simulationX' for designing hydraulic-pneumatic system of heave compensator for offshore drilling operations. Reliability verification of the analysis model for the test equipment of 1/5 scale compensator was conducted by comparing test results and simulation results. An analysis of full scale heave compensator is developed on the basis of verified a model. Then, the results of simulation were analyzed to obtain following conclusion. The displacement of crown block about excitation input amplitude (${\pm}3,000mm$) of the steward platform using a 'simulationX' is attenuated under ${\pm}35mm$, and the compensation rate is 98.7%. In this study, goal of a compensation rate is more than 95%. The previously results are satisfied with the objectives of compensation rate.

• Journal of Advanced Marine Engineering and Technology
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• 제31권3호
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• pp.252-262
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• 2007

In this paper, we suggest fuzzy control with feedforward compensator of superheat to progress both energy saving and coefficient of performance(COP) in a variable speed refrigeration system. The capacity and superheat are controlled simultaneously and independently by an inverter and an electronic expansion valve respectively for saving energy and improving COP in the system. By adopting the fuzzy control. the controller design for the capacity and superheat is possible without depending on a dynamic model of the system. Moreover, the feedforward compensator of the superheat can eliminate influence of the interfering loop between capacity and superheat. Some experiments are conducted to design the appropriate fuzzy controller by an iteration manner. The results show that the proposed fuzzy controller with the compensator can establish good control performances for the complicated refrigeration system with inherent strong non-linearity.

• 한국태양에너지학회 논문집
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• 제35권3호
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• pp.49-56
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• 2015

This paper presents a comparative operating characteristics of static var compensator(SVC) and static synchronous compensator(STATCOM) for compensating the reactive power in the Jeju power system. There are two kinds of reactive power compensating systems, which are active and passive system in the applications of the line commutated converter type high voltage direct current (LCC-HVDC). In the Jeju power system, two STATCOMs as active compensating system have been operating. Even though STATCOM has good performance compared with SVC, economical efficiency of former system is not good to the latter system. So, it is necessary to examine the performance and economical efficiency depend on the intention before appling the system. To compare the operating characteristics of two systems in the Jeju power system, simulations have been carried out for case studies that both of the HVDC system have transient state by using PSCAD/EMTDC program.

• 대한전기학회논문지:전력기술부문A
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• 제49권10호
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• pp.509-515
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• 2000

This paper addresses a damping control strategy of Static Synchronous Series Compensator(SSSC) and analysis model for stability study. The effect of injected voltage source generated by SSSC is modelled as equivalent load. This model is thought to be reasonable for the stability study because the dynamics of SSSC is very fast compared with that of power system. Damping controller of SSSC is based on Transient Energy Function method. The proposed control strategy is insensitive to the operating conditions like power flow level because control law depends on the phase angles. The proposed analysis model and control strategy was confirmed by WSCC 9 bus system and two area system. Especially, the robustness of proposed control strategy is demonstrated with respect to multiple operating conditions in two area system.

• Journal of Power Electronics
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• 제11권6호
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• pp.897-903
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• 2011

Many voltage sag compensators have been introduced, including the traditional dynamic voltage restorer (DVR), which requires an energy storage device but is inadequate for compensating deep and long-duration voltage sags. The AC-AC sag compensators introduced next do not require a storage device and they are capable of compensating voltage sags. This type of compensator needs an AC-AC converter to regulate the output voltage. Presented in this paper is a three-phase PWM-switched autotransformer voltage sag compensator based on an AC-AC converter that uses a proposed detection technique and PWM voltage control as a controller. Its effectiveness and capability in instantly detecting and compensating voltage sags were verified via MATLAB/Simulink simulations and further investigated through a laboratory prototype developed with a TMS320F2812 DSP as the main controller.

• 한국산업융합학회 논문집
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• 제21권4호
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• pp.149-158
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• 2018

With the propagation and spread of the new regeneration energy and increase in electricity demand, power systems tend to be decentralized, and accordingly, the use of a power system stabilizer tends to expand for the stabilization of the distribution system. Thus, typical power system stabilizer, Static Var Compensator (SVC) is developed on a variety of topologies. In addition, the trend of technology leads from SVC to Static Synchronous Compensator(STATCOM) technology development. Recently, to overcome STATCOM's conversion losses and economic disadvantages, studies of a hybrid method using STATCOM and SVC in parallel have actively been conducted. This study proposes a new Soft-Step Switching method to limit inrush current problematic in Thyristor Controlled Capacitor (TCC) method in SVC function. In addition, to reduce Statcom's capacity, groups of reactive power compensation reactor and condenser for SVC were designed.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.302-304
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• 1999

Voltage sag and swell are the most severe factors affecting power quality in distribution systems. This paper discusses an approach to ensure a high quality power supply to critical loads appling voltage-sag compensator. The proposed system consists of a PWM voltage source inverter, connected in series with the line through a single-phase transformer. The operation Principle and Power circuit configuration of the proposed voltage sag compensator are introduced. And then the transfer function of compensator is derived from simplified single phase power circuit, and simulated so that the benefits of this proposed compensator is confirmed through the open loop response.

• 한국정밀공학회지
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• 제28권4호
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• pp.455-462
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• 2011

This paper is about the design of a new gravity compensator for the lower body exo-skeleton device. The exo-skeleton devices is for increasing the torque of the human body joint for the purpose of helping the disabled, workers in the industry, and military soldiers. So far, most of studied exo-skeleton devices are actuated by the motors, but motors are limited in energy such that a short durability is always a big problem. In this paper, a new gravity compensator is proposed to reduce the torque load applied to human body joints due to gravity. The gravity compensator is designed using a tortional bar spring, and its structure and characteristics are studied through the test and computer simulation. A design concept on the exo-skeleton device using the gravity compensator is presented. An analysis and computer simulation on the torque reduction of the proposed exo-skeleton device that applies and non-applies the gravity compensator are performed.