5상 유도전동기의 파라미터 추정

김남훈(Namhun Kim),백원식(Wonsik Baik),김민회(Minhuei Kim),정형우(Hyungwoo Jung),김동희(Donghee Kim) 전력전자학회 2010 전력전자학술대회 논문집 Vol.2010 No.7

다상 유도 전동기(Multi phase induction motor)의 고성능 제어를 수행하기 위해서는 정확한 파라미터 계산이 필수적이다. 특히 전동기의 벡터제어(FOC, Field oriented control)나 직접 토크제어(DTC, Direct torque control)와 같은 고성능 제어 시스템의 경우, 슬립 계산이나 자속관측기 그리고 PI 제어기 게인 추정에서 전동기 상수들이 필수적으로 사용된다. 본 논문에서는 실험용으로 집중권(Concentrated winding) 구조를 가지는 2㎾, 5상 유도전동기를 제작하였으며, 5상 유도전동기 파라미터 추정에 대한 방법을 제시하였다. 일반적으로 다상 유도전동기의 경우 1차 공간 고조파(1st space harmonic) 성분에 대한 파라미터만을 추정하여 제어에 사용하지만, 본 논문에서는 1차 공간 고조파 성분과 3차 공간 고조파(3rd space harmonic) 성분에 대한 파라미터 추정 방법을 제시한다. 결과적으로 제안된 파라미터 추정 방법의 타당성을 확인하기 위해서 설계값과 실험값을 비교하였다.

FEM을 이용한 영구자석형 리럭턴스 동기 전동기의 설계에 대한 연구

김남훈(Namhun Kim),김민회(Minhuei Kim),백원식(Wonsik Baik),김동희(Donghee Kim) 전력전자학회 2007 전력전자학술대회 논문집 Vol.- No.-

In this paper, design of PMA-RSM(permanent magnet assisted reluctance synchronous motor) for washing machine using FEM(finite element method) is presented and algorithms to maximize electromagnetic torque is introduced. FEM has been approached to show the effects of motor parameters on the developed average torque and maximum torque. The designed motor is a combination of salient poles, which is making reluctance torque, and permanent magnet which are located on the air-gap of rotor to get a enough torque during low speed resign. And to verify availability of the proposed PMA-RSM, various simulation are done as compared with bldc motor which is used for washing machine.

팬용 플럭스 스위치 전동기 드라이브에 대한 연구

김남훈(Namhun Kim),김정철(Jungchul Kim),이중호(Joongho Lee),구본삼(Bonsam Koo),기민회(Minhuei Kim),백원식(Wonsik Baik) 대한전기학회 2009 대한전기학회 학술대회 논문집 Vol.2009 No.4

A new class of electronically commutated brushless motor, the flux-switching motor(FSM) is gradually emerging in power tools and household appliances especially fan application. This motor offers advantages of both high-power density and relatively high efficiency. This paper presents the principle of the FSM and design of the 12/6 pole FSM drive system. Finally, test results of the prototype motor are provided to verify a validity of the fan application.

Evaluating the Mechanical Properties of Fiber Yarns for Developing Synthetic Fiber Chains

Kyeongsoo Kim,Taewan Kim,Namhun Kim,Dokyoun Kim,Yongjun Kang,Seonjin Kim 한국해양공학회 2021 韓國海洋工學會誌 Vol.35 No.6

In this study, three types of synthetic fiber materials were evaluated, namely, DM20, SK78, and T147, to replace steel chains in shipbuilding and offshore fields with fiber chains as there is increasing demand for chains with lighter weights and improved usabilities. The strength and quasi-static stiffness were analyzed to select suitable yarns for the fiber chains. The durability of the yarn was evaluated by performing a 3-T (time to rupture) test as a specific tension level. The results of the experiment revealed excellent dynamic stiffness in DM20 and highest values of the windward and leeward stiffness in T147. 3-T linear design characteristic curves for a specific tension level were derived for the three types of fiber materials. The findings of this study can provide insights for improving strength and durability in fiber chain design.

잎갈나무와 일본잎갈나무의 물리 및 역학적 특성 비교

김성현 ( Seonghyun Kim ),김도훈 ( Dohoon Kim ),조재익 ( Jaeik Jo ),김종호 ( Jongho Kim ),김남훈 ( Namhun Kim ) 한국목재공학회 2020 한국목재공학회 학술발표논문집 Vol.2020 No.1

잎갈나무는 북한의 금강산 일대와 러시아 등 넓은 범위에 걸쳐 분포하고 있으나, 남한에서는 일부 지역 (국립수목원, 가리왕산, 강원대학교 학술림 등)에서만 분포하고 있는 수종으로 목재의 재질에 관한 연구들이 일부 보고되어왔다. 일본잎갈나무는 1970년대 산림녹화를 목적으로 진행된 치산녹화 사업으로 전국에 널리 식재되어 목재의 재질과 이용에 관한 다양한 연구들이 수행되어왔고, 현재 주요 국산 목재 자원으로 활용되고 있다. 하지만, 잎갈나무와 일본잎갈나무 목재의 재질특성을 비교한 연구는 부족한 실정이라 본 연구에서는 두 수종의 효율적인 활용을 위한 재질지표로서 기초자료를 제공하고자 물리 및 역학적 특성을 조사 및 비교하였다. 공시목은 강원도 춘천에 위치한 강원대학교 학술림에서 잎갈나무와 일본잎갈나무를 각각 3본씩 채취하여 사용하였다. 잎갈나무의 심재율과 만재율은 일본잎갈나무에 비해 높게 나타났으며, 잎갈나무의 연륜폭은 일본잎갈나무에 비해 좁았다. 잎갈나무의 생재함수율, 밀도, 수축률은 일본잎갈나무에 비해 높았다. 두 수종간의 종압축강도와 전단강도는 유사한 범위였으나, 심재부에서 잎갈나무의 종압축강도가 일본잎갈나무와 상당한 차이를 보여주었다. 잎갈나무의 경도는 모든 단면에서 일본잎갈나무에 비해 다소 작았다. 두 수종모두 종압축강도와 전단강도는 전건비중과 다소 높은 상관관계가 있었으며, 잎갈나무의 경도는 만재율 및 전건 비중과 높은 상관성이 확인되었다. 본 연구의 결과 잎갈나무와 일본잎갈나무재의 물리 및 역학적 특성간의 차이가 확인되었고, 향후 두 수종의 활용을 위한 재질지표로써 이용될 수 있을 것으로 판단된다.

Low Cost Rotor Fault Detection System for Inverter Driven Induction Motor

Namhun Kim,Changho Choi 대한전기학회 2007 Journal of Electrical Engineering & Technology Vol.2 No.4

In this paper, the induction motor rotor fault diagnosis system using current signals, which are measured using axis-transformation method, and speed, which is estimated using current information, are presented. In inverter-fed motor drives unlike line-driven motor drives the stator currents have numerous harmonics components and therefore fault diagnosis using stator currents is very difficult. The current and speed signal for rotor fault diagnosis needs to be precise. Also, high resolution information, which means the diagnosis system, demands additional hardware such as low pass filter, high resolution ADC, encoder and etc. Therefore, the proposed axis-transformation and speed estimation method are expected to contribute to low cost fault diagnosis systems in inverter-fed motor drives without the need for an encoder and any additional hardware. In order to confirm validity of the developed algorithms, various experiments for rotor faults are tested and the line current spectrum of each faulty situation using Park transformation and speed estimation method are compared with the results obtained from fast Fourier transforms.

Additive Manufacturing toward Industrial Production: The Additive Manufacturing Convergence Technology Center at UNIST

Namhun Kim(김남훈) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.5

Polymer bulk heterojunction solar cells with PEDOT:PSS bilayer structure as hole extraction layer.

Kim, Wanjung,Kim, Namhun,Kim, Jung Kyu,Park, Insun,Choi, Yeong Suk,Wang, Dong Hwan,Chae, Heeyeop,Park, Jong Hyeok Wiley-VCH 2013 ChemSusChem Vol.6 No.6

<P>A high current density obtained in a limited, nanometer-thick region is important for high efficiency polymer solar cells (PSCs). The conversion of incident photons to charge carriers only occurs in confined active layers; therefore, charge-carrier extraction from the active layer within the device by using solar light has an important impact on the current density and the related to power conversion efficiency. In this study, we observed a surprising result, that is, extracting the charge carrier generated in the active layer of a PSC device, with a thickness-controlled PEDOT:PSS bilayer that acted as a hole extraction layer (HEL), yielded a dramatically improved power conversion efficiency in two different model systems (P3HT:PC??BM and PCDTBT:PC??BM). To understand this phenomenon, we conducted optical strength simulation, photocurrent-voltage measurements, incident photon to charge carrier efficiency measurements, ultraviolet photoelectron spectroscopy, and AFM studies. The results revealed that approximately 60 nm was the optimum PEDOT:PSS bilayer HEL thickness in PSCs for producing the maximum power conversion efficiency.</P>

Perception-based analytical technique of evacuation behavior under radiological emergency: An illustration of the Kori area

Kim, Jeongsik,Kim, Byoung-Jik,Kim, Namhun Korean Nuclear Society 2021 Nuclear Engineering and Technology Vol.53 No.3

A simulation-based approach is proposed to study the protective actions taken by residents during nuclear emergencies using cognitive findings. Human perception-based behaviors are not heavily incorporated in the evacuation study for nuclear emergencies despite their known importance. This study proposes a generic framework of perception-based behavior simulation, in accordance with the ecological concept of affordance theory and a formal representation of affordance-based finite state automata. Based on the generic framework, a simulation model is developed to allow an evacuee to perceive available actions and execute one of them according to Newton's laws of motion. The case of a shadow evacuation under nuclear emergency is utilized to demonstrate the applicability of the proposed framework. The illustrated planning algorithm enables residents to compute not only prior knowledge of the environmental map, but also the perception of dynamic surroundings, using widely observed heuristics. The simulation results show that the temporal and spatial dynamics of the evacuation behaviors can be analyzed based on individual perception of circumstances, while utilizing the findings in cognitive science under unavoidable data restriction of nuclear emergencies. The perception-based analysis of the proposed framework is expected to enhance nuclear safety technology by complementing macroscopic analyses for advanced protective measures.

Modified Direct Torque Control System of Five Phase Induction Motor

Namhun Kim,Minhuei Kim 대한전기학회 2009 Journal of Electrical Engineering & Technology Vol.4 No.2

In this paper, improved direct torque control(DTC) of five-phase induction motor(IM) is proposed. Due to the additional degrees of freedom, five-phase IM drives present unique characteristics. One of them is the ability of enhancing the torque producing capability of the motor. Also fivephase motor drives possess many others advantage compared with the traditional three-phase motor drives. Such as, reducing the amplitude and increasing of frequency of torque pulsation, reducing amplitude of current per phase without increasing the voltage per phase and increasing the reliability. The direct torque control method is advantageous when it is applied to the five-phase IM. Because the fivephase inverter provides 32 space vectors in comparison to 8 space voltage vectors by the three-phase inverter. The 32 space voltage vectors are divided into three groups according to their magnitudes. The characteristics and dynamic performance of traditional five-phase DTC are analyzed and new DTC for five-phase IM is proposed. Therefore, a more precise flux and torque control algorithm for the fivephase IM drives can be suggested and explained. For presenting the superior performance of the proposed direct torque control, experimental results is presented using a 32 bit fixed point TMS320F2812 digital signal processor