Mo¨ssbauer 분광법을 이용한 10MnO_2-10Fe_2O_3-30Na_2O-50SiO_2 유리내의 Fe^3+ 이온에 관한 연구

洪致裕,朴冠鎬,白承道,洪性樂 동국대학교 1986 論文集 Vol.25 No.-

We have studied the Mo¨ssbauer parameters for Fe^(3+) ion in the quenched glass and heat treated glass and heat treated glasses. The Mo¨ssbauer spectra of the quenched glass were investigated at various temperatures from 60K to 300K. Using the center shift and kinetic temperature, the Debye and einstein temperatures were calculated. The quenched glass was heat-treated at various temperatures from 530℃ to 710℃ for five hours. Both the isomer shit and quadrupole splitting parameters decreased near 590℃. And regardless of heat treatment, the Fe^(3+) ion was predominantly octahedrally coordinated.

10MgO-10Fe_2O_3-30Na_2O-5OSiO_2 유리의 Mo¨ssbauer 효과 연구

홍치유,박관호,백승도,문찬호,조수열 동국대학교 1987 論文集 Vol.26 No.-

The Mo¨ssbauer effect studies of the quenched glass and heat-treated glasses were performed. The Debye and Einstien temperatures of the quenched glass, determined using the center shift and kinetic temperature, are 540K and 430K respectively. The X-ray diffraction pattern showed that the heat-treated glasses were crystallized. Form the isomer shift of the heat-treated glasses, it was concluded that the Fe^(3+) ion is predominantly octahedrally coordinated.

Mossbauer 분광법을 이용한 10MnO₂-10Fe₂O₃-30Na₂O-50SiO₂유리내의 Fe³+ 이온에 관한 연구

朴冠鎬,洪性樂,洪致裕,白承道 濟州大學校 基礎科學硏究所 1988 基礎科學硏究 Vol.1 No.1

We have studied the Mossbauer parameters for ?? ion in the quenched glass and heat treated glasses. The Mossbauer spectra of the quenched glass were investigated at various temperatures from 60K to 300K. Using the center shift and kinetic temperature, the Debye and Einstein temperatures were calculated. The quenched glass was heat-treated at various temperatures from 530℃ to 710℃ for five hours. Both the isomer shit and quadrupole splitting parameters decreased near 590℃. And regardless of heat treatment, the ?? ion was predominantly octahedrally coordinated.

알루미늄 롱넥 플랜지의 냉간 성형해석

허관도,여홍태 동의대학교 산업기술개발연구소 2001 産業技術硏究誌 Vol.15 No.-

This study is concerned with the analysis of deformation to make an aluminum long-neck flange by cold extrusion and upsetting processes. The process of deformation was analysed using DEFORM(a commercial rigid-plastic FEM code) to get informations such as distributions of effective strain, metal flow and the relationship between load and punch stroke on the variation of semi-extrusion angle. The diameter ratios of a prestressed die with one stress ring have been also considered to determine the dimension of each ring. In the results, it is found that the initial extrusion load as well as the final load increases according to the increase of semi-extrusion angle. Especially, at the final extrusion stage, the increase of semi-extrusion angle makes high the effective strain near the outer surface of workpiece along the longitudinal direction, but punch stroke is decreased. In flange forming by upsetting process, the variation of semi-extrusion angle does not affect much forming load, but the increase of semi-extrusion angle reduces the region of high deformation and punch stroke. It is also found that the maximum separated distance from mandrel to workpiece is linearly decreased by increasing semi-extrusion angle. Therefore, it is possible to control the parameters such as forming load, punch stroke, and effective strain, which have effect on the manufacturing process and product quality, by changing semi-extrusion angle.

통계적 기법을 이용한 마이크로 스피커 다이아프램의 최적형상설계에 관한 연구

안찬우,홍도관,최재기,박진우 東亞大學校附設 生産技術硏究所 2007 生産技術硏究所硏究論文集 Vol.12 No.-

This study uses response surface methodology to explain correlations between the objective function and design variables, fractional factorial design and central composite design were carried out. The change of shape of diaphragm, thickness of diaphragm and voice coil weight based on fractional factorial design and central composite design are made. Therefore this study carried to decide design variables for minimizing 1st natural frequency and maximizing 2nd natural frequency of diaphragm using response surface methodology and screening(fractional factorial design), we showed improved design variables.

진동억제용 다중동흡진기의 효과에 관한 연구

안찬우,김동영,홍도관 동아대학교 환경문제연구소 1998 硏究報告 Vol.21 No.2

In a number of cases it appears expedient to install several absorbers of smaller masses instead of one. This may be due to the need to distribute the absorber's response along the construction, restrictions on the absorber's installation and transportation and other reasons. The application of multimass absorbers is not limited to protection from harmonic actions. The complete optimization of the absorber's parameters reduces to resonance amplitude. So, we studied characteristic of main vibration system and multi dynamic absorber's system for the optimal natural frequency ratio and damping ratio of multi dynamic absorber. Also we obtain the optimization of the multi dynamic vibration absorber's parameters using computer simulation for the damped main vibration system. In designing multi dynamic vibration absorber, we are presented for the optimum values of the mass, spring constant and damping coefficient of multi dynamic vibration absorbers.

야뇨증 환아들의 심리사회적 특성에 대한 다기관 연구 : 행동 및 정서 문제를 중심으로

조수철,김재원,신민섭,황준원,한상원,박관현,이상돈,김경도,김건석,서홍진,이유식,정재용,김영균,문두건,남궁미경,한창희,조원열,김영식,배기수,이종국,정우영,신의진 大韓神經精神醫學會 2005 신경정신의학 Vol.44 No.6

Objectives : The aim of this study was to examine the behavioral and emotional problems associated with nocturnal enuresis in Korean children. Methods : Three hundred eighteen children with nocturnal enuresis, together with their parents, completed the Child Behavior Checklist (CBCL), Disruptive Behavior Disorder Scale according to DSM-IV (DBDS), Children's Depression Inventory (CDI), State-Trait Anxiety Inventory for Children (STAIC), and Piers-Harris Children's Self-Concept Scale (PHCSC). Ninety-three normal students were selected as the control group. Results : Compared to the normal control group, the mean scores with regard to the withdrawn, social problems, attention problems, delinquent behavior, aggressive behavior, externalizing problems and total problems profiles were significantly higher in the nocturnal enuresis group according to the CBCL results. The nocturnal enuresis group also scored significantly higher in the ADHD and ODD profiles of the DBDS. The nocturnal enuresis group was more depressed and anxious than the control group according to the results of the CDI and STAI. The mean score of the PHCSC was significantly lower in the nocturnal enuresis group when compared to the normal control group. Conclusion : The results of this study suggest that children with nocturnal enuresis in Korea have clinically relevant behavioral and emotional problems. The findings support the link between nocturnal enuresis and psychopathology in Korean children.

Development of an Ultra High Speed Permanent Magnet Synchronous Motor

Hong, Do-Kwan,Woo, Byung-Chul,Jeong, Yeon-Ho,Koo, Dae-Hyun,Ahn, Chan-Woo Korean Society for Precision Engineering 2013 International Journal of Precision Engineering and Vol.14 No.3

To accomplish the research of a PM synchronous motor driven by 15 kW at a rated speed of 120 krpm. This paper represents an approach to minimize the eddy current losses that occur frequently at high speeds. Various simulation and testing techniques are applied to grasp the physical phenomena. Here, sleeve thickness is proposed parameter for analysis. Finally, this paper studies the developed model which represents a tendency for minimizing eddy current loss, von-Mises stress, unbalance vibration response and maximizing critical speed. It comes to the conclusion that sleeve thickness should be chosen after considering the function of mechanical stress, critical speed and unbalance vibration response of the rotor. The design efficiency is well suited to the efficiency test, having a maximum error of 2.7%.

Design and Experimental Validation of a High-Speed Electric Turbocharger Motor Considering Variation of the <tex> ${\boldsymbol{L}}/{\boldsymbol{D}}$</tex> Ratio

Hong, Do-Kwan,Lee, Tae-Woo,Jeong, Yeon-Ho IEEE 2018 IEEE transactions on magnetics Vol.54 No.11

<P>The commercialized electric turbocharger (ETC) made by Valeo includes a high-speed switched reluctance motor (SRM), ball bearings, impeller, and controller. SRMs are generally very noisy and have low efficiency (70%) at high speed. No ETC has yet been commercialized that includes a permanent magnet (PM) motor. The Korea Electrotechnology Research Institute, Changwon, South Korea, is developing a high-speed surface PM type of synchronous motor and a pulse width modulation-driven inverter. This system operates at a power density of 3 kW/kg at 100000 r/min and is intended to fit 1600 cc diesel vehicles to reduce turbolag to within 0.5 s. The design and analysis of the PM synchronous motor (PMSM) for the ETC have been successful by considering the electric and mechanical performance using multiphysics analysis. Validation by experiment was performed and matched within 1% error in terms of the efficiency. Design, analysis, and experiments with the PMSM for ETC applications were conducted successfully by utilizing an action–reaction torque sensor and the resistance load test method.</P>

Optimum Design of Transverse Flux Linear Motor for Weight Reduction and Improvement Thrust Force Using Response Surface Methodology

Do-Kwan Hong,Byung-Chul Woo,Dae-Hyun Koo,Do-Hyun Kang IEEE 2008 IEEE transactions on magnetics Vol.44 No.11

<P>Permanent magnet (PM)-type transverse flux linear motors (TFLMs) are electromagnetic devices which can develop directly powerful linear motion. The unique configuration makes power of output higher than longitudinal motors, but also it makes characteristic analysis difficulties. This paper deals with an effective analysis of PM-type TFLM by 3-D equivalent magnetic circuit network method (EMCNM). This paper presents optimum design of PM-type TFLM to reduce the weight of the machine with the constraints of thrust and detent force using response surface methodology (RSM). RSM was well adapted to make the analytical model of the minimum weight with constraints of thrust and detent forces and enable the objective function to be easily created and a great deal of the time in computation to be saved. Therefore, it is expected that the proposed optimization procedure using RSM can be easily utilized to solve the optimization problem of electric machines.</P>