• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.29 no.5
• /
• pp.50-56
• /
• 2015

As rotor position is a reference of coordinate in vector control of PMSM, the information of exact rotor position is required. To measure the position of motors, hall-effect sensors, encoders, resolvers, etc. are used. Among these sensors, resolvers have good endurance in the variation of circumstance and can be used in a wide range of temperature, but resolvers are less exact than encoders. In addition, resolvers have a drawback that the output signal contains periodic error components. Thus, this paper proposes a compensation method for the unique position error in resolvers using Kalman filter to achieve high performance control of PMSM. The validity of the proposed scheme is demonstrated through simulation studies.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.06a
• /
• pp.360-366
• /
• 2001

This paper show the designing, manufacturing and performance test procedure of a high speed, fixed ratio planetary roller type traction drive as a speed reducer. The arrangement and size design for sun roller, planetary rollers and ring roller are carried out and a proper pre-load mechanism are adopted. To improve transmitting power capacity and endurance limit, nitro-carburized bearing steel and a synthetic traction oil are used. The manufactured and assembled traction drive operated successfully under unloaded conditions. Further tests for various load and speed conditions are executing now to improve the performance of the traction drive.

• Journal of Nutrition and Health
• /
• v.15 no.3
• /
• pp.194-201
• /
• 1982

The objective of this research was to examine the relationship between food habits and personality. Two kinds of questionaries were distributed to 130 American college students. The data showed high relationship between personality and food habits. Poor diet group showed lower personality scores in personal adjustment, Affiliation, and nurturance while the scores in lability and succorance were higher than better diet group. A Considerable correalationship between eating preferences and personality was found. Vegetarian had higher scores in self - confidence, achievement, endurance, and autonomy while meat group were more dominant more aggressive and more changeable. Most of sweet food group were obese and had higher personality scores in abasement and deference.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2008.03a
• /
• pp.579-582
• /
• 2008

PEM Fuel cell system was designed and constructed to use as a power source of unmanned aerial vehicles(UAV) in the present study. Sodium borohydride was selected as a hydrogen source and was decomposed by catalytic hydrolysis reaction. Fuel cell system consists of a fuel cell stack, a hydrogen generation system(HGS), and power management system(PMS). HGS was composed of a catalytic reactor, micropump, fuel cartridge, and separator. Hybrid power system between lithium-polymer battery and fuel cell was developed. The fuel cell system was integrated and packaged into a blended wing-body UAV. Energy density of the total system was 1,000 $W{\cdot}hr/kg$ and high endurance more than 5 hours was accomplished in the ground tests.

• Animal cells and systems
• /
• v.7 no.1
• /
• pp.69-73
• /
• 2003

Serum lipid and lipoprotein levels are influenced by genetic factors, and exorcise increases the concentrations of cardio-protective parameters such as high-density lipoprotein cholesterol (HDL-cholesterol) and apolipoproteinAI (apoAI) in human serum. In the present study, we tested the effect of adaptation to endurance exercise on the association of a genetic polymorphism (Pst 1 RFLP) in the apoAI gene with these biochemical parameters. The genotype and allele frequencies for the Pst 1 RFLP were not significantly different between the elite athletes and sedentary controls (P>0.05). There were also no significant associations between the Pst 1 RFLP of the apoAI gene and the biochemical parameters in elite athletic group. Thus, our results suggest that the Pst 1 RFLP of the apoAI gene was not significantly associated with the serum apoAI and HDL-cholesterol concentrations as well as athletic performance in Koreans.

• Journal of the Korean Society for Aviation and Aeronautics
• /
• v.27 no.1
• /
• pp.51-56
• /
• 2019

To reduce the structural weight, thin-walled circular composite tube has been used as a main spar of high altitude-long endurance unmanned air vehicle(HALE UAV). Predicting the torsional response of stiffened circular spar is complex due to the inhomogeneous nature of section properties, which are dependent on fiber architecture and constituent material properties. The stiffener were placed in the top and bottom sectors of a tube to increase the torsional capabilities such as the rigidity and buckling strength. Numerical simulations were performed to estimate the effect of the stiffener on the torsional capacities. A static experimental test was performed on a stiffened tube, and the test results were compared with a numerical model. The numerical models showed good correlation and demonstrated the ability to predict the torsional capacity. Results presented herein will exhibit the effectiveness of stiffener on torsional strength and stiffness.

• Proceedings of the KIPE Conference
• /
• 2020.08a
• /
• pp.253-254
• /
• 2020

High Voltage Direct Current (HVDC) 시스템은 고압 직류송전을 위한 시스템이다. 고압 직류 송전을 위해서는 전력변환기가 교류전력을 직류전력으로 변환해주어야 하는데, 최근에는 모듈형 멀티레벨 컨버터(Modular Multilevel Converter, MMC)가 많이 적용되고 있다. MMC는 다수의 서브모듈이 직렬로 구성되어 있으며 DC-link단에 대용량 커패시터가 없다. MMC의 심각한 사고 중에 하나는 DC측 전력케이블의 단락사고로 시스템에 따라서 수십 kA 정도의 사고전류가 AC측 CB(Circuit Breaker)가 열리기 전까지 수십 ms에서 수백 ms동안 흐른다. 만약 하프브릿지 회로의 서브모듈로 구성된 컨버터에 별도 보호장치가 없으면 단락전류는 서브모듈의 하단 다이오드를 통해서 흐르게 되어 소손되게 된다. 이를 방지하기 위해 단락전류를 바이패스(by-pass) 시키기 위한 별도의 사이리스터를 추가하는데 이 기기의 사양은 DC 단락 전류를 충분히 견딜 수 있어야 한다. 본 논문에서는 사이리스터의 서지 전류 내력을 평가하기 위해 사양을 분석하고 시뮬레이션과 실험을 통해서 검증하였다.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2023.05a
• /
• pp.245-246
• /
• 2023

The unit curtain wall is an exterior finish currently used on the exterior walls of high-rise buildings. Curtain walls used as non-endurance walls are largely classified into stick curtain walls and unit curtain walls, and their use has recently been on the rise to reduce risks at construction sites through factory manufacturing. Accordingly, this study attempted to examine the insulation performance according to the shape of the unit curtain wall profile through insulation simulation.

• Transactions on Electrical and Electronic Materials
• /
• v.11 no.4
• /
• pp.155-165
• /
• 2010

As a promising candidate to replace the conventional floating gate flash memories, polysilicon-oxide-nitride-oxidesilicon (SONOS)-type nonvolatile semiconductor memories have been investigated widely in the past several years. SONOS-type memories have some advantages over the conventional floating gate flash memories, such as lower operating voltage, excellent endurance and compatibility with standard complementary metal-oxide-semiconductor (CMOS) technology. However, their operating speed and date retention characteristics are still the bottlenecks to limit the applications of SONOS-type memories. Recently, various approaches have been used to make a trade-off between the operating speed and the date retention characteristics. Application of high-k dielectrics to SONOS-type memories is a predominant route. This article provides the state-of-the-art research progress of high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories. It begins with a short description of working mechanism of SONOS-type memories, and then deals with the materials' requirements of high-k dielectrics used for SONOS-type memories. In the following section, the microstructures of high-k dielectrics used as tunneling layers, charge trapping layers and blocking layers in SONOS-type memories, and their impacts on the memory behaviors are critically reviewed. The improvement of the memory characteristics by using multilayered structures, including multilayered tunneling layer or multilayered charge trapping layer are also discussed. Finally, this review is concluded with our perspectives towards the future researches on the high-k dielectrics applicable to SONOS-type nonvolatile semiconductor memories.

• The Korean journal of sports medicine
• /
• v.36 no.4
• /
• pp.189-196
• /
• 2018

Purpose: The purpose of this study was to compare the difference of body mass index (BMI) to smart phone proficiency in men and women over the age of 60. Methods: Patients were divided into three groups with high (n=33), average (n=34), and low (n=33) smart phone proficiency. Fitness characteristics related to smart phone usage were evaluated by measuring cardiorespiratory endurance, grip strength, eye-hand coordination. As well, smart phone proficiency was evaluated by a self-reported questionnaire and a smart phone usability task that was composed of two categories: usage of the smartphone device itself and usage of phone applications. The differences in BMI of the subjects was analyzed by analysis of covariance adjusting for independent variables including age, smartphone usage period, eye-hand coordination, education and income. Results: There was a significant difference in BMI among the three groups after adjustment of age, eye-hand coordination, smartphone usage period, education and income. The results showed that the self-reported questionnaire showed a significant difference in BMI between high proficiency and low proficiency groups (high $24.88{\pm}2.46$, low $23.37{\pm}2.56$; p=0.037). Smart phone usability test results also showed a significant difference in BMI among the three groups (high $25.18{\pm}2.58$, low $23.15{\pm}2.6$; p=0.000 and high $25.18{\pm}2.58$, middle $23.57.7{\pm}1.69$; p=0.010). Conclusion: Our results suggest that high smart phone proficiency shows increased BMI in the elderly. This study suggests that people over the age of 60 who have high smartphone proficiency should be cautious of an increased BMI score.