승객보호장구 충돌성능 평가를 위한 6세 유아 인체모델 개발

김헌영(Heonyoung. Kim),김준식(Joonsik Kim),김상범(Sangbum Kim),이인혁(Inhyeok Lee),이진희(Jinhee Lee) 한국자동차공학회 2003 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

This study is focused on the development of the child model. 6-year old model is composed of skin, skeleton and joints. The dimension of child outer skin is refered to anthropometric data from KRISS (Korea Research Institute of Standards and Science). The positions of joint and mass properties of body segments are calculated from ARB(Ariticulated Rigid Body) program GEBOD. To verify the developed human model, ROM simulation and sled test is conducted. Developed human model can be effectively applied to the evaluation of human injury in crash situation and development of child restraind system.<br/>

가속도 신호를 이용한 실시간 연속체 구조물 변형 평가 기술 개발

김헌영(Heonyoung Kim),최현선(Hyunseon Choi),김형규(Hyeonggyu Kim),이진혁(Jinhyuk Lee),공원식(Wonsik Kong),김정석(Chungseok kim) 한국비파괴검사학회 2022 한국비파괴검사학회 춘계학술대회 초록집 Vol.2022 No.5

자동차 도어시일 신뢰도 평가 시스템 개발

김헌영(Heonyoung Kim),김형종(Hyungjong Kim),김호(Ho Kim),이종강(Jongkang Lee),김도형(Dohyung Kim) 한국자동차공학회 2004 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-

FEM analysis is commonly used in design process of automotive industry. In the area of rubber product, application of FEM tools is also authorized in their usefulness, but only with experimental method than any other material. The importance of comparing analysis and experimental result in design process has been grown because of so many existing variance of rubber. Door-Seal has no exception or has more connection with the comparing work on reaction force, contact time, contact area, deformed shape even though this work should be done by manually and takes some times. The Door-Seal evaluation system is developed by this requirement with image processing method and documentation.

Experimental investigation of long-term effects on temperature reliability of exothermic coating for smart railway structures with self-heating surfaces

Heonyoung Kim,Myeongcheol Kang,황문영,강래형,Chulmin Joo,Donghoon Kang 국제구조공학회 2021 Smart Structures and Systems, An International Jou Vol.27 No.1

Gravel scattering, which occurs from snow-ice that develops on trains during winter, is a major cause of damage to train parts. An exothermic technology that uses copper wires to solve the problem of gravel scattering is ineffective on the snow-ice produced on the surface of the trains. Therefore, studies have been conducted to overcome the weaknesses of the conventional methods and to develop a paint-type surface exothermic technology that can be efficiently applied to complicated structures. However, multi-layered paint-type coatings can lead to problems such as a delamination or exfoliation of the layers when used for a long period of time within an environment undergoing variations in temperature. Therefore, this study assesses the long-term effects of temperature on multi-layered exothermic coating technology based on nano-solutions for an application of self-heating function on railway infrastructures. To do so, we developed an exothermic coating test specimen using the paint applied to train cars and commercial nano-solutions. To conduct an experiment on accelerated aging, the specimen was subjected to regular changes in the temperature within a thermal chamber. The results revealed that there is a nonlinear decline in the performance as the specimen is worn out in comparison to the exothermic performance achieved during the early stages. Further, it is possible to identify the structural causes of the decline in performance from the specimen applied thermal load by analyzing the morphology. However, it is possible to observe a high stability from noninvasive overheating or short-circuits based on the structural changes to the coating, which are observed during the assessment of the exothermic uniformity. Therefore, it can be concluded that a multi-layer exothermic coating, which can be effectively applied as an exothermic technology based on self-heating surfaces, can be applied for a long period to prevent disasters from freezing or snow-ice in trains during winter.

Nondestructive evaluation on dispersion of steel fibers in UHPC using THz electromagnetic waves

Kim, Heonyoung,Kang, Donghoon,Oh, Seung Jae,Joo, Chulmin Elsevier 2018 Construction and Building Materials Vol.172 No.-

<P><B>Abstract</B></P> <P>Ultra-high performance concrete (UHPC), which has better mechanical properties and durability than reinforced concrete, can greatly reduce the weight of structures due to its high strength and reliability. So, it is very effective for the construction of high-rise buildings and long-span bridges. The mix design for UHPC is not only composed of traditional materials (i.e. cement, sand, and aggregate) but also includes binder and admixture. Moreover, steel fiber is necessary to improve ductility. Since the tensile strength of UHPC depends greatly on the direction of the steel fiber, it is important to confirm the dispersibility and orientation of the steel fiber. However, verification of the dispersibility of the steel fiber after curing is indirectly performed through destructive methods like strength tests through coring. Thus, for a better method of dispersibility confirmation, a more effective dispersion analysis technique is required. In this study, the dispersibility of steel fiber in UHPC was evaluated through tomography of UHPC using THz electromagnetic waves. These waves have both infrared straightness and microwave penetrability. Three UHPC specimens were fabricated with steel fiber and were tested with THz electromagnetic wave spectroscopy by experimentally scanning the specimen. From the experimental results, it was possible to obtain a 3D image of the steel fiber arrangement inside the specimen through scanning of the specimen. Also, through image analysis, the dispersibility of the steel fiber in each specimen was numerically derived. For the future, it is expected that the dispersion analysis technology proposed in this study will be applied as an automated nondestructive testing method for enhanced quality control.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Dispersibility of the steel fiber in UHPC is destructively evaluated like coring. </LI> <LI> THz waves can be used as a new test method for detecting steel fiber in UHPC. </LI> <LI> Dispersibility of steel fiber is quantitatively evaluated using THz 3D images. </LI> <LI> This technology can be used as automated NDT method for enhanced quality control. </LI> </UL> </P>

Reliable Detection of Rotor Faults Under the Influence of Low-Frequency Load Torque Oscillations for Applications With Speed Reduction Couplings

Heonyoung Kim,Sang Bin Lee,Sungbong Park,Kia, Shahin Hedayati,Capolino, Gerard-Andre IEEE 2016 IEEE transactions on industry applications Vol.52 No.2

<P>Low-frequency torque oscillations in the load can induce frequency components in the vicinity of that of rotor faults (RFs) resulting in false alarms when applying motor current signature analysis (MCSA). False RF indications due to load oscillations (LO) are most common in applications that employ speed reduction couplings for high torque, low-speed operation. Recently, ideas for separating RF and LO have been proposed in the literature; however, the case where two components overlap at the same frequency has not been investigated. Several cases where RF- and LO-induced components are identical have been observed in the field by the authors with commercial MCSA equipment. It is shown in this paper that overlap between the two components can produce a false positive or false negative indication because they can add or cancel depending on the relative phase between the components. Alternative options for reliable RF testing among existing test methods are evaluated and verified in this paper for cases where the two components overlap and produce false indications.</P>

Development of exothermic system based on internet of things for preventing damages in winter season and evaluation of applicability to railway vehicles

Heonyoung Kim,Donghoon Kang,주철민 국제구조공학회 2022 Smart Structures and Systems, An International Jou Vol.29 No.5

Gravel scattering that is generated during operation of high-speed railway vehicle is cause to damage of vehicle such as windows, axle protector and so on. Especially, those are frequently occurred in winter season when snow ice is generated easily. Above all, damage of vehicle windows has not only caused maintenance cost but also increased psychological anxiety of passengers. Various methods such as heating system using copper wire, heating jacket and heating air are applied to remove snow ice generated on the under-body of vehicle. However, the methods require much run-time and man power which can be low effectiveness of work. Therefore, this paper shows that large-area heating system was developed based on heating coat in order to fundamentally prevent snow ice damage on high-speed railway vehicle in the winter season. This system gives users high convenience because that can remotely control the heating system using IoT-based wireless communication. For evaluating the applicability to railroad sites, a field test on an actual high-speed railroad operation was conducted by applying these techniques to the brake cylinder of a high-speed railroad vehicle. From the results, it evaluated how input voltage and electric power per unit area of the heating specimen influences exothermic performance to draw the permit power condition for icing. In the future, if the system developed in the study is applied at the railroad site, it may be used as a technique for preventing all types of damages occurring due to snow ice in winter.

The Influence of the LC with Clamping Diodes dv/dt Filter on Current Control of PMSM Drives in Case of Inverter Output Current Sensing and Its Compensation

Heonyoung Kim,Byeong-Heon Kim,Subhashish Bhattacharya 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

This paper presents effect of LC with clamping diodes dv/dt filter on current-controlled PMSM drives in case where 3-phase inverter output currents are measured and used in the digital control loop. In particular, this case can be reported in some cases. Firstly, power devices are equipped with integrated pilot current sensors. Secondly, PCB technology based Rogowski coils are installed in inverter leg with analog circuit to feed a signal to microcontroller. Thirdly, hall type current sensors are packaged in inverter output terminal through a bus bar. In those cases, it is inevitable to measure inverter currents because it is hard to move the location of current sensor. In this manner, the effect of filter resonance should be considered properly to control the motor current accurately because the measured inverter output current includes both motor and filter resonant current. If the resonant current of the filter is not compensated properly, it causes the DC offset of motor current which bring about the torque ripples. In order to compensate the offset, inserting a two stage Discrete Fourier Transform (DFT) is used and the calculated offset is subtracted from the sampled current. Judging by simulation and experimental results, it is confirmed that the compensation method eliminates the offset of the motor current effectively, and thereby reducing the torque ripple as well.

Improved EEMF-Based Position Sensorless Control for Non-sinusoidal Back-EMF PMSMs

Kim Heonyoung,Lee Kibok,Bhattacharya Subhashish 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.2

A restricted number of the stator and rotor slots in PMSMs distorts the air-gap fl ux distribution and eff ective air-gap length. Such distortions result in varying machine parameters with rotor position. In particular, the rotor fl ux linkage harmonics cause a non-sinusoidal back-EMF, which introduces machine harmonic currents if PI current controllers are employed. As a result, it deteriorates the rotor position estimation performance in extended EMF (EEMF)-based sensorless control. This is because both sinusoidal machine current and back-EMF are assumed for the rotor position estimation. Such degradation of the angle estimation performance can result in controller trips due to overcurrent, especially in the case of step load changes. This paper presents a detailed modeling of the harmonic rotor fl ux linkage and voltage, and introduces virtual rotor fl ux linkage terms in the synchronous reference frame to simplify the harmonic voltage terms. From the harmonic voltage model, a harmonic voltage injection method is proposed in addition to conventional EEMF-based sensorless control. The proposed scheme can provide sinusoidal motor current control for entire operating conditions. Additionally, experimental results confi rm that the proposed control method can achieve the improved performance of the EEMF-based sensorless control

THz 전자기파를 이용한 나노시멘트 광학물성 측정

김헌영(Heonyoung Kim),강동훈(Donghoon Kang),오승재(Seung Jae Oh),주철민(Chulmin Joo) 한국비파괴검사학회 2016 한국비파괴검사학회지 Vol.36 No.5

탄소나노튜브와 그래핀 등으로 대표되는 탄소 동소체기반 나노재료의 우수한 기계적 특성을 이용해 콘크리트의 압축강도를 증가시키기 위한 연구가 활발히 진행되고 있다. 일반적으로, 나노재료 적용을 통한 강도 향상을 위해서는 콘크리트 내 나노재료의 분산성이 높아야 하며, 이를 검증하기 위해 외부에서 비파괴적으로 확인할 수 있는 검사 기술이 요구된다. 본 연구에서는, 적외선의 직진성과 마이크로파의 투과성을 동시에 갖고 있는 THz 전자기파를 이용하여 MWCNT 및 GO가 포함된 두 종류의 나노시멘트 모르타르 시편을 제작하여 굴절률 및 흡수율과 같은 기초 광학물성 측정 시험을 수행하였다. 시험을 통해 일반 시멘트 모르타르에 비해 나노재료가 포함된 시편에서 굴절률은 평균 1.0~2.5%, 흡수율은 평균 –14~28% 차이로 측정됨을 확인하였다. 이를 통해, 비파괴적으로 콘크리트 내부에 포함된 나노재료의 분포도를 영상화할 수 있는 기술의 실현 가능성을 확인하였다. Enhancing mechanical strength of concrete has been fascinated using carbon-based nanomaterials such as CNT and graphene. The key to improving strength is a dispersion of nanomaterials. A novel method is required to investigate the dispersion inner concrete nondestructively. In this study, the optical optical properties such as refractive index and absorption coefficient are measured in nano-cement mortar specimens containing MWCNT and GO using THz electro-magnetic waves. From the results, the properties of nano-cement mortar are confirmed to be 1.0% to 2.5% higher in refractive index, and –14% to 28% higher in absorption coefficient than those of cement mortar at the average values. Using these characteristics, visualizing the dispersion of nano-concrete structures seems possible in future.