• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.1-7
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• 2018

Electric motors for electric vehicles differ in efficiency characteristics depending on the operation modes, studies for evaluating high efficiency characteristics in low speed and high speed operation modes are very important. Therefore, it is necessary to design method that can change the high torque, high output density, and high efficiency characteristics of driving motors for electric vehicles. In this paper, the diameter ratio of stator and rotor for the interior permanent magnet synchronous motor is change of designed 0.62, 0.65, and 0.68, respectively, and the efficiency characteristics of the entire operation section, average efficiency characteristics of the city driving modes and express highway driving modes are analyzed. As a result of analyzing the efficiency characteristics of the entire operating section, it was confirmed that as the diameter ratio increases, the high efficiency section moves to the low speed and low torque section and the high efficiency section moves to the high speed and low torque neighborhood as the diameter ratio decreases. As a result of analyzing the average efficiency characteristics in the city driving modes and express highway driving modes, the average efficiency of 0.68 model is analyzed to be more efficient than the 0.63 and 0.65 model ratio, and it is confirmed that it is suitable for city driving modes and express highway driving modes.

• Polymer(Korea)
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• v.38 no.4
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• pp.471-476
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• 2014

Polycarbonate (PC) and acrylonitrile-butadiene-styrene (ABS) blends were prepared using a high shear extruder to investigate their thermal decomposition and mechanical properties with shear rate and shear time. In this experiment, high shear rate, from 1000 to 3000 rpm, in blending process was applied for 10 to 40 sec, respectively. At high shear rate over than 2000 rpm, the initial decomposition temperature was dropped significantly compared to a compounded sample because of thermal decomposition of the blend by high shear. Consequently, high shear processing gave an important effect on the mechanical and thermal properties of the PC/ABS blend. In particular, elongation of the blend decreased significantly with shear rate.

• Journal of the Institute of Electronics Engineers of Korea TE
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• v.42 no.1
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• pp.29-34
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• 2005

The wound induction motor can provide high starting torque and reduced starting current simultaneously by inserting large resistor externally when starting. And this technique is one of the well known methods among the induction motor starting methods and generally used for heavy load starting such as crane and cement factories. The conventional PI controller has been widely used in industrial application due to the simple control algorithm and is generally used for control of current torque, position, and speed for the wound induction motor drive system. However, the conventional control system for wound induction motor may result in poor performance because sensors have to be used but are often limited by the environmental condition. Recently, to overcome these problems, many sensorless vector control methods for the wound induction motor have been studied. This paper presents a MRAS method for sensorless vector control of the wound induction motor drive. In the conventional MRAS method, in low frequency, the stator resistance variation may result in poor performance. Therefore, this paper presents a MRAS method with stator and rotor resistance tuning for sensorless vector control of the wound induction motor to overcome several shortages of the conventional MRAS caused by parameter variation and to enhance the robustness of the sensorless vector control. The validity and effectiveness of the proposed method is verified through digital simulation.

• Journal of KIISE:Databases
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• v.36 no.2
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• pp.73-83
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• 2009

In this paper we propose an object similarity matching method based on shape characteristics of an object in an image. The proposed method extracts edge points from edges of objects and generates a log polar histogram with respect to each edge point to represent the relative placement of extracted points. It performs the matching in such a way that it compares polar histograms of two edge points sequentially along with edges of objects, and uses a well-known k-NN(nearest neighbor) approach to retrieve similar objects from a database. To verify the proposed method, we've compared it to an existing Shape-Context method. Experimental results reveal that our method is more accurate in object matching than the existing method, showing that when k=5, the precision of our method is 0.75-0.90 while that of the existing one is 0.37, and when k=10, the precision of our method is 0.61-0.80 while that of the existing one is 0.31. In the experiment of rotational transformation, our method is also more robust compared to the existing one, showing that the precision of our method is 0.69 while that of the existing one is 0.30.

• Progress in Medical Physics
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• v.26 no.2
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• pp.87-92
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• 2015

The gated RapidArc may produce a dosimetric error due to the stop-and-go motion of heavy gantry which can misalign the gantry restart position and reduce the accuracy of important factors in RapidArc delivery such as MLC movement and gantry speed. In this study, the effect of stop-and-go motion in gated RapidArc was analyzed with varying gating window time, which determines the total number of stop-and-go motions. Total 10 RapidArc plans for treatment of liver cancer were prepared. The RPM gating system and the moving phantom were used to set up the accurate gating window time. Two different delivery quality assurance (DQA) plans were created for each RapidArc plan. One is the portal dosimetry plan and the other is MapCHECK2 plan. The respiratory cycle was set to 4 sec and DQA plans were delivered with three different gating conditions: no gating, 1-sec gating window, and 2-sec gating window. The error between calculated dose and measured dose was evaluated based on the pass rate calculated using the gamma evaluation method with 3%/3 mm criteria. The average pass rates in the portal dosimetry plans were $98.72{\pm}0.82%$, $94.91{\pm}1.64%$, and $98.23{\pm}0.97%$ for no gating, 1-sec gating, and 2-sec gating, respectively. The average pass rates in MapCHECK2 plans were $97.80{\pm}0.91%$, $95.38{\pm}1.31%$, and $97.50{\pm}0.96%$ for no gating, 1-sec gating, and 2-sec gating, respectively. We verified that the dosimetric accuracy of gated RapidArc increases as gating window time increases and efforts should be made to increase gating window time during the RapidArc treatment process.

• Korean Journal of Applied Biomechanics
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• v.12 no.2
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• pp.91-107
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• 2002

This research got the following conclusion as result that analyzed high clear action kinematically to 4 C girls' junior high school badminton players who are situated in Chungchong-bukdo. 1. Most of the subject didn't rotate their right shoulder and elbow joint at back swing and moved speedy to shuttle cock. And an cooperation action of joint decreases displaying only a good action on both subject`s specification joint part. 2. When the subject S1 and S2 swing slowly and largely the joint of shoulder and elbow and then the speed of right wrist and racket head is fast, the cooperation action of joint is better than other subject. 3. An angle change of right shoulder showed angle that all subjects are great being caused in softness of joint and angular velocity was exposed that load enough Impact force and increase the speed of racket head as angular velocity decreases rapidly in Impact except subject S3. 4. All subjects of right elbow angle change showed similar form and was exposed that subject S2 sees form of impact stage serious bends from back swing and do not use force effectively in angular velocity. 5. Angle of right wrist appeared that the speed of shuttle cock is decelerated because fast bends of wrist is not formed shortly after Impact because all subject do not accomplish big angle shortly after back swing. Angular velocity can assume that the subject S1 and S4 are using and move fast strong snap shot offering angular velocity value of Impact stage sound (-). 6. While size of Impact stage knee angle accomplishes angle that is big both subject, hip joint angles sees small angle and is playing swing that do on upper body and arm without using strong waist force that is composition action with knee and hip joint.

• The Korean Journal of Nuclear Medicine
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• v.29 no.4
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• pp.533-540
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• 1995

Attenuation correction is important in producing quantitative positron emission tomography (PET) images. Conventionally, photon attenuation effects are corrected using transmission measurements performed before tracer administration. The pre-injection transmission measurement approach may require a time delay between transmission and emission scans for the tracer studies requiring a long uptake period, about 45 minutes for F-18 deoxyglucose study. The time delay will limit patient throughput and increase the likelihood of patient motion. A technique lot performing simultaneous transmission and emission scans (T+E method) after the tracer injection has been validated. The T+E method substracts the emission counts contaminating the transmission measurements to produce accurate attenuation correction coefficients. This method has been evaluated in experiments using a cylindrical phantom filled with background water (5750 cc) containing $0.4{\mu}Ci/cc$ of F-18 fluoride ion and one insert cylinder (276 cc) containing $4.3{\mu}Ci/cc$. GE $Advance^{TM}$ PET scanner and Ge-68 rotating pin sources for transmission scanning were used for this investigation. Post-injection transmission scan and emission scan were peformed alternatively over time. The error in emission images corrected using post-infection transmission scan to emission images corrected transmission scan was 2.6% at the concentration of $1.0{\mu}Ci/cc$. No obvious differences in image quality and noise were apparent between the two images. The attenuation correction can be accomplished with post-injection transmission measurement using rotating pin sources and this method can significantly shorten the time between transmission and omission scans and thereby reduce the likelihood of patient motion and increase scanning throughput in PET.

• Journal of Korean Society of Transportation
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• v.24 no.3 s.89
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• pp.177-187
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• 2006

It is known that over one million car navigation devices are being currently used in Korea. Most. if not all, route guidance systems, however, Provide only one "best" route to users, not providing any options for various types of users to select. The current practice dose not consider each individual's different preferences. These days, a vast amount of information became available due to the rapid development in information processing technology. Thus, users Prefer choices to be given and like to select the one that suits him/her the "best" among available information. To provide such options in this Paper, we developed an algorithm that provides alternative routes that may not the "least cost" ones, but ones that are close to the "least cost" routes for users to select. The algorithm developed and introduced in the paper utilizes a link-based search method, rather than the traditional node-based search method. The link-based algorithm can still utilize the existing transportation network without any modifications, and yet enables to provide flexible route guidance to meet the various needs of users by allowing transfer to other modes and/or restricting left turns. The algorithm developed has been applied to a toy network and demonstrated successful implementation of the multi-path search algorithm for multi-purpose activities.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4C
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• pp.239-246
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• 2005

In this paper. we generate a virtual right image corresponding to the input left image by using given RGB texture data and 8 bit gray scale depth data. We first transform the depth data to disparity data and then produce the virtual right image with this disparity. We also proposed a stereo image synthesis algorithm which is adaptable to a viewer's position and an real-time processing algorithm with a fast LUT(look up table) method. Finally, we could synthesize a total of eleven stereo images with different view points for SD quality of a texture image with 8 bit depth information in a real time.

• 한국정보교육학회:학술대회논문집
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• 2004.08a
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• pp.475-484
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• 2004

공간 능력 및 공간 시각화 능력의 향상은 우리가 살고 있는 세계를 표현하고 설명하는데 도움을 주고 실생활과 직업에 관련된 문제해결 능력을 기를 수 있게 한다. 초등학교에서는 비형식적인 방법으로 일상생활에서 접하는 대상과 다른 구체적 자료를 사용한 조사, 실험, 탐구를 통하여 여러 위치에서 도형을 시각화하고, 그려보고, 비교하는 활동을 강조하고 있다. 제7차 수학과 교육과정에서 공간능력 및 공간 시각화 능력을 향상시키기 위한 학습으로 구체적 조작물과 학습지 사용을 병행하고 있다. 하지만 초등 기하는 공간적인 경험을 현실 상황이나 구체물 조작을 통하여 형성된 공간직관을 수학화하도록 하여야 하나, 실제 현장에서는 학교여건 등의 여러 실정으로 조작 자료들이 제대로 마련되어 있지 않거나 잘 사용하지 않고 있다. 3차원을 경험할 수 있는 공간 시각화 학습프로그램을 적극 활용하여 어떤 방향이든 상관없이 가상의 공간에서 물체를 옮기거나 회전시킬 수 있으며 시간적, 공간적 제약을 받지 않고 학습자들의 공간시각화 능력을 향상시킬 수 있는 학습 프로그램 개발이 필요하다. 이에 본 연구에서는 이런 요구에 의해 아동과의 상호 작용성과 접근성을 향상시킨 웹기반 가상현실 프로그램을 개발하고 그 효과 분석을 통해 웹 기반 가상현실 학습 프로그램에 대한 가능성을 진단해 보고자 한다.