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VGT와 EGR이 장착된 디젤엔진의 공기순환계 모델에 관한 연구
정동영(Dong-Young Jeong),정재우(Jae-Woo Chung),강정호(Chung-Ho Kang),김남호(Nam-Ho Kim),정진은(Jin-Eun Chung) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
The recent Diesel engine is to install VGT(variable geometry turbocharger) to increase the engine displacement per the power, to reduce the CO2 generation by increasing the BSFC and to minimize the turbo-reg at low speed-load points. And the EGR system is installing for reducing the NOx generation. The VGT and EGR were operated complexly in the engine intake and the exhaust system. Therefore, this study focuses to modify VGT dimensionless model using the flow, efficiency and power parameters which are temperature, pressure and mass flow. and this models were developed to predict the intake and the exhaust state in engine. In case of the Combination with the model which are turbocharger model, intercooler model, exhaust gas model, it is possible to predict intake and exhaust state which are boost temperature, pressure ratio, after intercooler gas temperature, before the turbine pressure and the turbine vane duty using just mass air flow rate within reasonable errors. And in case of introduce the another additional independent parameter, it is possible to increase the prediction accuracy.
유동 에너지 균형을 이용한 EGR 측정 기술 개발에 관한 연구
정동영(Dong-Young Jeong),정재우(Jae-Woo Chung),김남호(Nam-Ho Kim),강정호(Chung-Ho Kang),서영호(Young-Ho Seo),정수진(Soo-Jin Jeong) 한국자동차공학회 2009 한국자동차공학회 학술대회 및 전시회 Vol.2009 No.11
This study focuses the another measurement way of EGR rate without Horiba exhaust analyser. it uses the flow energy balance which is intercooler heat rate plus EGR gas heat rate equals intake manifold. The result of comparison of engine test, the heat transfer should be considered especially Hot HP EGR loop system because EGR gas temperature is higher than cooled HP EGR loop. The correction coefficient considering to heat transfer was fined by using heat rate error for NEDC mode test with 2000cc common rail DME engine. The result of mode test shows the validity of the measurement of EGR rate through the comparison of NOx.
포트폴리오 프로그램의 대안평가 활용에 대한 특수교육 교사의 인식
정소영 ( Dong Young Chung ),정동영 ( So Young Jeong ) 한국특수아동학회 2011 특수아동교육연구 Vol.13 No.3
본 연구는 포트폴리오 프로그램을 대안평가 도구로 활용하기 적절한지에 대한 특수교육 교사들의 인식을 알아보는데 목적을 두고, 초등학교 특수교육 교사 104명을 선정하여 근무기관과 담당학년별로 실험집단과 비교집단으로 구분하여 한 집단에 각각 13명씩 배정한 후 실험집단에만 ``포트폴리오 프로그램을 적용하고 적용 전후에 대안평가 인식검사를 실시하여 특수교육 교사들의 인식 변화를 비교하였다. 본 연구의 결과 포트폴리오 프로그램의 적용을 통해 특수학교 교사들은 특수학급 교사들보다 포트폴리오 프로그램을 타당하고 신뢰롭고 효율적인 대안평가 도구로 인식하게 되었으며, 저학년 담당 특수교육 교사들은 고학년 담당 특수교육 교사들보다 포트폴리오 프로그램을 효과적이고 효율적인 대안평가 도구로 인식하게 된 것으로 나타났다. 따라서 특수교육 교사들은 포트폴리오 프로그램의 적용을 통하여 포트폴리오 프로그램을 대안평가 도구로 활용하기에 신뢰성, 타당성, 효율성 및 효과성을 지닌 것으로 인식하게 되었다고 할 수 있다. The purpose of this study is to investigate the special education teachers` perception on the use of portfolio as an alternative assessment. Based on institution of employment and appointed grade, 104 elementary special education teachers were selected into experimental groups and comparative groups with 13 teachers respectively. First, the results showed that there were differences in the impact on special education teacher`s perception of alternative assessment depending on the institution of employment. In particular, the special school teachers` perception of reliability, validity, and efficiency increased significantly compared to that of special class teachers. Secondly, the results indicated that there were differences in the impact on the special education teacher`s perception of alternative assessment depending on the appointed grade level. In particular, the lower grade special class teachers` perception of efficiency and effectiveness significantly increased compared to that of higher grade special class teachers. As seen above, special education teachers improved their perception for alternative assessment by using portfolio assessment. Teachers who work at special education schools perceive portfolio assessment as a useful assessment tool ensured with reliability, validity, and efficiency. Teachers who work in lower grade classes perceive portfolio assessment as a useful assessment tool ensured with efficiency and effectiveness. Therefore, portfolio program should be presented to the students as an alternative assessment method ensured with reliability, validity, efficiency, and effectiveness.
KISE-BAAT(수학)의 신뢰도와 타당도에 관한 연구
박경숙 ( Kyung Sook Park ),정동영 ( Dong Young Chung ),정인숙 ( In Suk Jeong ),송영준 ( Young Jun Song ),김계옥 ( Kye Ok Kim ) 한국특수아동학회 2005 특수아동교육연구 Vol.7 No.3
본 연구는 국립특수교육원(Korea Institute for Special Education)의 수학 기초학력검사(Basic Academic Achievement Test: Math)인 KISE-BAAT(수학)의 신뢰도와 타당도를 확인하는데 목적을 두고 있다. 본 연구는 목적을 달성하기 위하여 전국의 유·초·중학교에 재학 중인 만 5~14세의 아동 2,000명을 대상으로 KISE-BAAT(수학)를 실시하였다. 연구의 결과 KISE-BAAT(수학)의 동형검사 신뢰도는 전체적으로 .89이고, 영역별로 .36에서 .97의 범위에 분포하고 있는 것으로 나타났으며, 반분신뢰도는 전체적으로 가형과 나형 공히 .98이고, 학년별·영역별로 가형은 .39에서 .96을, 나형은 .28에서 .95를 범위로 하고 있는 것으로 나타났다. 문항반응이론 신뢰도는 전체적으로 가형 .97, 나형 .99이고, 학년별·영역별로 가형은 .69에서 .97를, 나형은 .77에서 .95를 범위로 하고 있는 것으로 나타났으며, 측정의 표준오차는 전체적으로 가형 2.11, 나형 2.32이고, 학년별·영역별로 가형은 0.7에서 1.54를, 나형은 .07에서 1.79를 범위하고 있는 것으로 나타났다. 재검사신뢰도는 전체적으로 가형과 나형 공히 .98이고, 영역별로는 가형과 나형 공히 .88에서 .97을 범위로 하고 있는 것으로 나타났으며, 문항 내적 일치도는 전체적으로 가형과 나형 공히 .99이고, 영역별로 가형은 .25에서 .96을, 나형은 .37에서 .97을 범위로 하고 있는 것으로 나타났다. 그리고 KISE-BAAT(수학)와 KEDI-기초학습기능검사와의 상관계수는 전체적으로 가형 .70, 나형 .75이고, 가형 시간과 화폐와 .62, 나형 암산과 .66으로 나타났다. 따라서 KISE-BAAT(수학)는 신뢰도와 타당도에서 비교적 양호한 수학 기초학력 검사도구라 할 수 있다. The purpose of this study is to investigate validity and reliability of KISE-BAAT(Math). KISE-BAAT(Math) test was administered 2,000 students from kindergarten, elementary and middle school level. The results of the study presented that overall alternate-form reliability coefficient is .89 and by subtest it ranges from .36 and .97. Split-half reliability coefficient of each alternate form shows high level of reliability of .98. By grade and subtest it ranges from .39 through .96 for Form A and .28 through .95 for Form B. The overall item response theory reliability coefficient of each alternate form also presents high level of .97 and .99. By grade and subtest it ranges from .69 through .97 for Form A and .77 through .95 for Form B. The overall standard error of measurement of each alternate form presents 2.11 and 2.32 respectively. By grade and subtest it ranges from 0.7 through 1.54 for Form A and .07 through 1.79 for Form B. The overall test-retest reliability coefficient of each alternate form presents .98. By grade and subtest it ranges from .88 through .97 for both forms. Cronbach``s coefficient alpha of each alternate form presents high level of reliability of .99. By grade and subtest it ranges from .25 through .96 for Form A and .37 through .97 for Form B. As for the ontent validity related expert team worked from the stage of setting up standards of achievement, developing test items. The item tryout was administered to select and arrange test items. The criterion -related validity in terms of the relationship with KEDI-Basic Academic Ability Test was examined. The validity coefficient of each alternate form and KEDI-Basic Academic Ability Test showed .70 and .75 respectively. As for intercorrelation coefficient between subtests range from .81 to .95. The results demonstrate that KISE-BAAT(Math) is relatively reliable and valid test instrument.
정진은(Jin-Eun Chung),정동영(Dong-young Jeong),정재우(Jae-Woo Chung),강우(Woo Kang) 한국자동차공학회 2008 한국자동차공학회 춘 추계 학술대회 논문집 Vol.- No.-
Today, tight and contradictory demands concerning the performance, the exhaust quality and higher milage require the complex system in the engine, such as the combinations of turbochargers. In this engine the control becomes more difficult, Therefore the simple and accurate model for the turbocharger is necessary. This paper deals with the prediction of the compressor performance. The universal curve for flow map and Jenson-Kristensen method for the efficiency map are used. To verify these maps, some measurements were carrying out on the test bench and compared with the results of simulation. As a result of comparison, we can show that the error is inside 5% and it is possible to make 2nd equation compressor performance. Also model using AMESim & IFP engine library is similar to predicted values using universal curve and Jenson-Kristensen method.