Restart Strategy for Scalar Controlled Synchronous Reluctance Machine Driving a High-Inertia Load with a Single DC-link Current Sensor

Kibok Lee,Srdjan M. Lukic 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper proposes an approach for implementing the restart for Synchronous Reluctance Machines (SynRMs) driving a high inertia load. The proposed method uses a simple identification algorithm to estimate the rotor speed and position of the machine so that the appropriate voltage vector can be applied to the machine, thus minimizing the inrush current at the instant of the restart. The novelty is that its implementation only requires nameplate machine parameters and a single DC-link current sensor. The proposed method is suitable for implementation with both high-inertia vector and scalar-controlled SynRMs.

TCSC Dynamic Free Distance Protection Scheme Using Backward Blocking Signals

Kibok Lee(이기복),Heejin Kim(김희진),Jongseo Na(나종서),Kyeon Hur(허견) 대한전기학회 2019 대한전기학회 학술대회 논문집 Vol.2019 No.4

사회과 교사 전문성으로서의 교수내용지식(PCK) 형성ㆍ강화와 교육대학원 교육과정

이기복(Kibok Lee) 한국사회과교육연구학회 2011 사회과교육 Vol.50 No.4

본 연구는 교육대학교 교육대학원 사회과 교육과정을 중심으로 사회과 교사의 현장적 요구를 충족하고 교과 전문성 신장을 위하여 현재 운영되고 있는 교육과정 구성 실제를 분석하여 사회과 교사 전문성으로서의 교수 내용 지식(Pedagogical Content Knowledge : PCK) 과의 관계를 파악하고, 사회과 교사전문성으로서 교수 내용 지식 형성과 신장을 위한 교육과정 개선이 급변하는 사회변화에 대한 효율적인 교육적 대응을 위한 중요한 방법 내지는 전략임과 동시에 교육대학원 개설 목적에 부합하는 교육과정으로의 접근을 위한 필수적인 조치임을 강조하고자 하였다. 현직 교사들에게 새로이 요구되는 전문성 신장ㆍ강화를 위해 교사교육 과정인 교육대학원 교육과정에서 필요한 것은 교사들에게 실천을 통한 반성적 사고를 할 수 있는 기회를 제공하는 일이며, 교육현장 중심의 교사 전문 지식을 확보할 수 있는 기회를 제공해 주어야 하기 때문이다. The purpose of this study is to search for the program of Expertise of the Social Studies Teacher base on the concept of Pedagogical Content Knowledge. The PCK was pursued in terms of the professionality of the Social Studies Teacher as interpretor or translator of domain-specific contents, topics, and ideas to learners with diverse characteristics. Main features of the Social Studies PCK are a personal knowledge domain featuring each teacher’s unique professionalism, synthetic in that it builds up separate knowledge domain into a connected whole, and experiential and practical knowledge that is situated in personal experience both inside and outside the classroom. For the intensification of Expertise of the Social Studies Teacher base on the Concept of PCK, we need the graduate school at the university of elementary teacher that would play a decisive role as the intensification and substitution system for the PCK as Expertise of the Social Studies Teacher. However, it is a pity that the present graduate schools have heavily focused on the promotion of scholastic abilities. therefor, the schools are in need of carrying out professional curriculum.

Performance evaluation of mask R-CNN for lung segmentation using computed tomographic images

Nam Kibok,Lee Dahye,Kang Seonghee,Lee Seungwan 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.4

Image segmentation techniques based on machine learning are able to improve diagnostic and therapeutic accuracy by localizing target areas. The accuracy and efciency of these techniques are dependent on network architecture and loss minimization method because the performance of a machine learning model is determined by training strategies. In this study, the lung segmentation based on computed tomographic images was performed by using mask regional convolutional neural networks (R-CNNs) with various feature extraction networks and optimizers. The efects of the feature extraction networks and optimizers on the trained mask R-CNNs were evaluated in terms of total training loss, segmentation accuracy and training time. The results showed that the convergence of total loss values during network training was afected by the architectures of the feature extraction networks as well as the optimizers. The lung segmentation accuracy and training time of the mask R-CNN were mainly dependent on the optimizer and network architecture, respectively. Among the various optimizers, the ASGD optimizer maximized lung segmentation accuracy, and the training time was reduced by the feature extraction network including general convolution layers and feature pyramid network (FPN). In conclusion, it is important to apply the optimal network architecture and optimizer to the mask R-CNN for maximizing its performance, and the optimized mask R-CNN can be potentially used for improving diagnostic and therapeutic accuracy.

s-IGDT 시스템의 X-선원 배열 형태 및 투영상 개수에 따른 영상 화질 평가에 관한 연구

이다혜(Dahye Lee),남기복(KiBok Nam),이승완(Seungwan Lee) 대한방사선과학회(구 대한방사선기술학회) 2022 방사선기술과학 Vol.45 No.2

Although stationary inverse-geometry digital tomosynthesis (s-IGDT) is able to reduce motion artifacts, image acquisition time and radiation dose, the image quality of the s-IGDT is degraded due to the truncations arisen in projections. Therefore, the effects of geometric and image acquisition conditions in the s-IGDT should be analyzed for improving the image quality and clinical applicability of the s-IGDT system. In this study, the s-IGDT images were obtained with the various X-ray source arrangement types and the various number of projections. The resolution and noise characteristics of the obtained s-IGDT images were evaluated, and the characteristics were compared with those of the conventional DT images. The s-IGDT system using linear X-ray source arrangement and 40 projections maximized the image characteristics of resolution and noise, and the corresponding system was superior to the conventional DT system in terms of image resolution. In conclusion, we expect that the s-IGDT system can be used for providing medical images in diagnosis.

Synergistic interaction between metal ions in the sea salts and the extracellular polymeric substances for efficient microalgal harvesting

Lee, Hansol,Nam, Kibok,Yang, Ji-Won,Han, Jong-In,Chang, Yong Keun Elsevier 2016 Algal research Vol.14 No.-

<P><B>Abstract</B></P> <P>Artificial sea salts were found to cause microalgal flocculation and was so rather effectively in the presence of extracellular polymeric substances (EPS). EPS-producing species <I>Ettlia</I> sp. YC001 formed flocs at relatively low salt concentration: at 3.5g/L, it reached up to 90% of the flocculation within 2h. EPS non-producer <I>Chlorella vulgaris</I> UTEX 265, on the other hand, was less responsive to the salts even at 7g/L and it had only 42% of floc formation. This phenomenon of salt-mediated flocculation appeared to be brought about mainly by calcium ion, as it has had greater affinity to the EPS than any other ions including the divalent magnesium ion. This sea salt-based coagulation may serve as one environmental-friendly alternative to commonly used chemical flocculants, which also potentially possess an economic merit.</P>

미국과 일본의 중대형차 연비 규제안 비교 분석

김기복(Kibok Kim),염시호(Siho Yeom),박진일(Jinil Park),이종화(Jonghwa Lee) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

Around the world consider a reducible method of greenhouse gas because of obligation to reduce greenhouse gas emissions. Regulations are strictly application at normal cars. But heavy duty vehicles regulations confirm only U.S. and Japan. In this paper Compare U.S and Japan`s fuel economy regulations of heavy duty vehicles based on simulation and classified fuel economy. It also classify Heavy duty Vehicles of domestic production depending on USA&Japan regulation

시내버스에서 변속 지시기 적용에 따른 실도로 연비 특성 분석

김기복(Kibok Kim),염시호(Siho Yum),박진일(Jinil Park),이종화(Jonghwa Lee),박경석(Kyoungseok Park),박준홍(Junhong Park) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

A shift pattern is a very important factor on a vehicle fuel economy. Especially for manual transmission vehicles, a fuel economy varies according to a driver’s tendency. If an indicator put a driver on notice of gear shift on pertinent point of time, the fuel economy can be improved. This paper focuses on fuel economy improvement through change of gear shifting engine speed and presents a gear shift algorithm considering a traction force, an APS, a vehicle acceleration and a BSFC(Brake Specific Fuel Consumption). Shift Indicate Algorithm considering a measure or calculate of engine speed, vehicle acceleration depend on APS, engine efficiency, traction force after gear shifted. Drivers can shift along embedded computer of applied shift algorithm. From simulation result of simulink and Cruse(AVL), we verify an algorithm. and parameter tuning from field test. The specification of test vehicle is 11000㏄ CNG engine, manual transmission. and the test condition is two cases, regular drive of bus company driver and drive depend on shift indicator. driving route is urban bus line of suwon city. Our team got a result from field test, 18% of vehicle fuel economy improvement can be achieved comparing to regular drive. that is because of higher engine efficiency, lower engine speed and lower acceleration.

시내버스 변속 패턴에 따른 연비 특성 분석

김기복(Kibok Kim),박진일(Jinil Park),이종화(Jonghwa Lee),박경석(Kyoungseok Park),김우석(Wooseok Kim) 한국자동차공학회 2009 한국자동차공학회 부문종합 학술대회 Vol.2009 No.4

A shift pattern is a very important factor on a vehicle fuel economy. Especially for manual transmission vehicles, a fuel economy varies according to a driver's tendency. If an indicator put a driver on notice of gear shift on pertinent point of time, the fuel economy can be improved. This paper focuses on fuel economy improvement through change of gear shifting engine speed and presents a gear shift algorithm considering a traction force, an APS, a vehicle acceleration and a BSFC(Brake Specific Fuel Consumption). The bigger portion of high gear stage is, the better the engine efficiency and lower total cycle there will be. So the fuel economy of the vehicle becomes better. The specification of test vehicle is 6000㏄ diesel engines and the test condition is two cases, shift on high engine speed and shift on low engine speed. In the case of real experiment on the road, when the shift the gears at the normal condition, it was showed a preponderance of 25% at the shift on low engine speed in the average of twice experiments but the result of only 9% at the shift on high engine speed. That is, the lower engine speed is, the better fuel economy is presented. There are similar result at the simulation. However, if the engine speed is low in a gear shift, the vehicle can not be sufficient traction force. So, vehicle speed will be low or the section that can not follow required vehicle speed is occurred. In order to improve these problems, presented a gear shift algorithms that is considering a traction force. Our team got a shift profile to algorithm and applied it to the simulation. As a result, 13.7% of vehicle fuel economy improvement can be achieved comparing to normal condition.

머신러닝을 활용한 시내버스 연비 운전 점수화 알고리즘 개발

김기복(Kibok Kim),이종화(Jonghwa Lee),박진일(Jinil Park) 한국자동차공학회 2022 한국자동차공학회 학술대회 및 전시회 Vol.2022 No.11

An eco-drive system was implemented on urban buses in Seoul. The system includes a shift indicator and the calculation of eco-drive score. With the implementation, 3,864 vehicles showed improvement in fuel economy by 12.1% annually. The eco-drive score indicates the degree of fuel economy of driving by monitoring acceleration and deceleration, timing of gear shift, accelerator pedal gradient, and coasting rate. During the annual operation, the eco-drive score showed discrepancy depending on the driving environment. This revealed the need to improve the linearity between fuel economy and the score. The eco-drive score was calculated based on OBD data, and external factors such as traffic environment and road conditions were not considered. In this study, the environmental factors of fuel economy were identified to supplement the eco-drive score. This is achieved by developing a machine learning fuel economy prediction model. The environmental factors are examined by assessing the contribution of each input variable (feature) of the fuel economy prediction model through SHAP-value. The driving start time, driving date, number of gear shifts per unit distance, and brake operation ratio during driving were set as the environmental factors of fuel economy. The measured fuel economy is normalized using the relationship between the average fuel economy and each of the environmental factor of the annual driving data. The eco-drive score is corrected in the range of 0.84-1.05 times based on the normalized fuel economy distribution of the equivalent eco-drive score. A corrected eco-drive score prediction model was developed, and the environmental factor of the fuel economy was used as the prediction model feature of the eco-drive score. The eco-drive score increased with an increase in the normalized fuel economy. The correlation between fuel economy and eco-drive score was 34% improved by considering the environmental factors of fuel economy.