• 한국산학기술학회논문지
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• 제11권8호
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• pp.2750-2757
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• 2010

현재 전문대학의 자동차 학과에서 제공되는 교육이 이론교육에 치우쳐 실제 산업현장에서 적용과 응용능력에 문제점이 있다고 지적이 있어왔다. 이 연구는 창의적인 자동차설계 능력을 배양하기 위하여 A 대학의 모터스포츠 전공에서 차량 공기역학에 $CO_2$ 경주차 설계를 수행한 성공적인 수업내용의 사례를 살펴본다. $CO_2$ 모형 경주차 제작 규정, 제작 과정, 성능 시험 등시 제시 되었으며, $CO_2$ 모형 경주차의 속도 및 항력이 측정되었다. 공학설계가 학생들의 학습에 미친 영향을 알아보기 위하여 2008년 봄 학기에 설문조사를 실시하였다. 설문조사에 따른면 학생들의 공학설계 능력과 만족도에 높은 가치를 부여하였다.

• 항공우주기술
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• 제3권2호
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• pp.56-64
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• 2004

본 연구에서는 소형위성발사체의 고체모터 가동노즐용 추력벡터제어 구동장치를 제어하기 위한 컴퓨터 하드웨어 설계에 관한 내용을 기술하였다. 구동장치 제어 컴퓨터는 관성항법장치로부터 제어명령을 받아 작동기를 구동하는 장치로, 발사체 내외의 다른 장비들과 통신을 하는 기능도 갖추고 있다. 구동장치 제어 컴퓨터는 고속의 제어 알고리즘 연산에 적합하도록 디지털 시그널 프로세서를 주 프로세서로 채택하여 KSR-III의 아나로그 제어기와 비교할 때 안정성과 신뢰성, 유연성을 더 갖추도록 설계하였다. 설계된 제어 컴퓨터는 여기 프로그램 개발용 타겟 보드 제작을 거쳐 1차 시제품으로 개발되었다. 여기에서는 최상위단계의 설계 요구조건과 하드웨어 구성, 지상지원장비에 대해서도 기술하였다.

• 한국자동차공학회논문집
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• 제22권2호
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• pp.166-174
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• 2014

Fuel injection pressure has steadily increased in diesel engines for the purpose of improving fuel efficiency and cleaning exhaust gas, but it has now reached a point, where the cost for higher pressure does not warrant additional gains. Common rail systems on modern diesel engines have fuel pumps that are mechanically driven by crankshaft. The pumps actually house two pumping module inside: a low pressure pump component and a high pressure pump component. Part of the fuel compressed by the low pressure component returns to the tank in the process of maintaining the pressure in the common rail. Since the returning fuel represents pumping loss, fuel economy improves if the returned fuel can be eliminated by using a properly controled electrical fuel pump. As the first step in developing an electrical fuel pump the fuel supply system on a 6 liter diesel engine was modeled with AMESim to analyze the workload and the fuel feed rate of the injection pump, and the results served as basis for selecting a suitable servo motor and a reducer to drive the pump. A motor controller was built using a DSP and a program which controls the common rail pressure using a proportional control method based on the target fuel pressure information from the engine ECU. A test rig to evaluate performance of the fuel pump is implemented and used to show that the newly developed electrically driven fuel pump can satisfy the fuel flow demand of the engine under various operating conditions when the rotational speed of the pump is adequately controlled.

• Progress in Superconductivity
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• 제13권1호
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• pp.40-46
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• 2011

A superconductor flywheel energy storage system (SFES) is an electro-mechanical battery which transforms electrical energy into mechanical energy for storage, and vice versa. A 10 kWh class flywheel energy storage system (FESS) has been developed to evaluate the feasibility of a 35 kWh class SFES with a flywheel $I_p/I_t$ ratio larger than 1. The 10 kWh class FESS is composed of a main frame, a composite flywheel, active magnetic dampers (AMDs), a permanent magnet bearing, and a motor/generator. The flywheel of the FESS rotates at a very high speed to store energy, while being levitated by a permanent magnetic bearing and a pair of thrust AMDs. The 10 kWh class flywheel is mainly composed of a composite rotor assembly, where most of the energy is stored, two radial and two thrust AMD rotors, which dissipate vibration at critical speeds, a permanent magnet rotor, which supports most of the flywheel weight, a motor rotor, which spins the flywheel, and a central hollow shaft, where the parts are assembled and aligned to. The stators of each of the main components are assembled on to housings, which are assembled and aligned to the main frame. Many factors have been considered while designing each part of the flywheel, stator and frame. In this study, a 10 kWh class flywheel energy storage system has been designed and constructed for test operation.

• 한국철도학회논문집
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• 제18권2호
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• pp.87-93
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• 2015

선형동기전동기(이하 LSM)를 기반으로 하는 자기부상열차의 경우 부상전자석의 대응면이 LSM의 고정자로 요철 형상을 가지고 있기 때문에 주행 시 부상력이 급변동하는 특징이 있다. 특히, LSM을 이용하는 초고속 자기부상열차의 경우, 고속주행을 위해 부상전자석을 대차에 직접 채결하는 방식을 채택하는데 이러한 체결방식 때문에 인접한 부상전자석들간의 운동 간섭이 심하여 대차에 피치운동이 심하게 발생한다. 이러한 문제들을 해소하기 위해 본 논문에서는 피치운동을 반영한 자기부상제어를 소개한다. 제안하는 부상제어는 개별 부상 전자석의 부상공극을 일정하게 유지시켜 줄 뿐만 아니라 인접한 부상전자석들간의 상대운동을 저감하는데 큰 효과가 있다. 제안한 개념을 시험용 자기부상열차에 적용하여 그 효용성을 검증한다.

• Journal of Power Electronics
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• 제15권1호
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• pp.146-159
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• 2015

Since the power capacity needed for the propulsion of large ships is very large, a multiphase AC induction propulsion mode is generally adopted to meet the higher requirements of reliability, redundancy and maintainability. This paper gives a detailed description of the development of a 20MW fifteen-phase PWM driver for advanced fifteen-phase propulsion induction motors with a special third-harmonic injection in terms of the main circuit hardware, control system design, experiments, etc. The adoption of the modular design method for the main circuit hardware design can make the enclosed mechanical structure simple and maintainable. It can also avoid the larger switch stresses caused by the multiple turn on of the IGBTs in conventional large-capacity converter systems. The use of the distributed controller design method based on a high-speed fiber-optic ring net for the control system can overcome such disadvantages as the poor reliability and long maintenance times arising from the conventional centralized controller which is designed according to point-to-point communication. Finally, the performance of the 20MW PWM driver is verified by experimentation on a new fifteen-phase induction propulsion motor.

• 융합신호처리학회논문지
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• 제10권4호
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• pp.262-266
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• 2009

산업 현장에서 요구하는 위치제어계는 고속, 고정밀의 제어를 만족하여야 하므로, 취급과 제어가 용이하고 응답특성이 우수한 직류 서보 전동기를 많이 이용하고 있다. 위치제어계에서 제어 성능을 개선시키기 위해서 많은 위치제어기법들이 제안되어져 왔다. 본 논문에서는 I-PD 위치제어계에서 PD제어기를 설계할 수 있는 설계법을 제안하였다. 제안한 설계법은 계의 전달함수를 정규화하여 제어계에서 제어기의 계수들이 결정되도록 하였다. 그리고 계의 안정조건과 근의 조건을 수학적으로 유도하였다. 이 방법을 I-PD제어계에 적용하여 PD제어기의 비례 및 미분 계수를 결정하였다. 그리고 이 제어기법을 적용한 I-PD 제어계를 시뮬레이션하여 계단 입력신호 및 외란 인가 시 계의 응답을 고찰하여 제안한 제어기법의 유효성을 검토하였다.

• 대한통합의학회지
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• 제8권4호
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• pp.107-115
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• 2020

Purpose: This study aims to systematically review the dual-task evaluation applied to the screening of mild cognitive impairment. It also aims to present various evaluation items and results analysis methods for dual tasks applied to patients with mild cognitive impairment. Methods: We conducted a systematic search of published studies in PubMed databases and KISS from January 2000 to August 2020 using the main keywords such as "Dual task," "Mild Cognitive impairment," "Elderly," and "Screening." We selected a total of 10 studies for the analysis from 1314 searched articles. Results: We analyzed the qualitative level of 10 studies that were nonrandomized two-group studies with evidence level II (100.0%). These results suggest that the evidence level of the studies was high. We analyzed 10 studies and identified 12 motor tasks and 19 cognitive tasks. Walking was the most commonly used evaluation motor task and counting backward by ones and naming animals were the most commonly used evaluation cognitive tasks. Moreover, the velocity speed was the most used result analysis method. The results indicate that there were significant differences in dual-task performance between patients with normal and mild cognitive impairment. Conclusion: The results of this study can be used as a basis for the selection of dual-task evaluation items and methods of analyzing the results for screening mild cognitive impairment. Furthermore, they are expected to be used for research on the development of dual-task evaluation tools. It is necessary to compare and analyze the usage trends of dual-task evaluation by cultural differences in future studies.

• 대한의용생체공학회:의공학회지
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• 제43권1호
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• pp.27-34
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• 2022

Drunk driving defines a driver as unable to drive a vehicle safely due to drinking. To crack down on drunk driving, alcohol concentration evaluates through breathing and crack down on drinking using S-shaped courses. A method for assessing drunk driving without using BAC or BrAC is measurement via biosignal. Depending on the individual specificity of drinking, alcohol evaluation studies through various biosignals need to be conducted. In this study, we measure biosignals that are related to alcohol concentration, predict BrAC through SVM, and verify the effectiveness of the S-shaped course. Participants were 8 men who have a driving license. Subjects conducted a d2 test and a scenario evaluation of driving an S-shaped course when they attained BrAC's certain criteria. We utilized SVR to predict BrAC via biosignals. Statistical analysis used a one-way Anova test. Depending on the amount of drinking, there was a tendency to increase pupil size, HR, normLF, skin conductivity, body temperature, SE, and speed, while normHF tended to decrease. There was no apparent change in the respiratory rate and TN-E. The result of the D2 test tended to increase from 0.03% and decrease from 0.08%. Measured biosignals have enabled BrAC predictions using SVR models to obtain high Figs in primary and secondary cross-validations. In this study, we were able to predict BrAC through changes in biosignals and SVMs depending on alcohol concentration and verified the effectiveness of the S-shaped course drinking control method.

• 대한통합의학회지
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• 제11권3호
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• pp.49-57
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• 2023

Purpose : This study aimed to systematically review the correlation between hand dexterity and cognitive function in the elderly, and summarize various evaluation tests and results analysis methods for manual dexterity tests applied to this population. Methods : We searched published studies in the Korean Studies Information Service System and PubMed databases from January 2013 to March 2023. The main keywords used were "dexterity," "fine motor," "elderly," "cognitive function," and "correlation." A total of 10 studies were selected for analysis from the 1,524 searched articles. The included studies consisted of a cohort study, a longitudinal study, and eight cross-sectional studies which were analyzed for patients, intervention, comparison, and outcomes. Results : Analyzing the qualitative level of 10 studies, 8 articles (80%) were non-randomized two-group studies that provided level II evidence whereas the remaining 2 studies (20%) were non-randomized single-group studies (level III evidence). Therefore, these results indicated that the level of evidence in this field is generally high. The Purdue pegboard test was the most commonly used evaluation test for manual dexterity, and velocity speed was the most frequently employed analysis method. Results indicated that there were significant differences in manual dexterity test between the normal elderly, those with mild cognitive impairment, or dementia. Conclusions : These results can be used as a basis for selecting dexterity test evaluation items and methods to analyze it in the elderly while screening for cognitive impairment. In addition, this study highlights potential areas for future research on the development of manual dexterity evaluation tools and techniques for analysis and the need for more reliable and valid methods for assessing cognitive function in the elderly.