• 한국산학기술학회:학술대회논문집
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• 한국산학기술학회 2010년도 춘계학술발표논문집 2부
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• pp.769-772
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• 2010

The objective of the current research work is to investigate the usage of biodiesel combined with the use of EGR in order to reduce the emission of all regulated pollutants from diesel engines. A single cylinder, air cooled, constant speed direct injection diesel engine was used for the experimental work and a cold EGR system was developed and fitted to the engine. Concentrations of HCs, NOx, and CO from the exhaust gas along with the smoke opacity were measured. Engine performance parameters such as the brake thermal efficiency (BTE) and the brake specific energy consumption (BSEC) were also calculated from the measured data. The results from the present investigation suggest that 25-30% EGR rate could give excellent NOx reduction without any significance penalty on smoke opacity or BSEC under the engine load of up to 40%. Under the full load condition, 15% EGR rate was found to be an option while higher EGR rate resulted in inferior performance and heavy smoke.

• Advances in Computational Design
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• 제4권4호
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• pp.367-379
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• 2019

Multiple Inputs and Multiple Outputs (MIMO) Fuzzy logic model is developed to predict the engine performance and emission characteristics of pongamia pinnata biodiesel with hydrogen injection. Engine performance and emission characteristics such as brake thermal efficiency (BTE), brake specific energy consumption (BSEC), hydrocarbon (HC), carbon monoxide (CO), carbon dioxide ($CO_2$) and nitrous oxides ($NO_X$) were considered. Experimental investigations were carried out by using four stroke single cylinder constant speed compression ignition engine with the rated power of 5.2 kW at variable load conditions. The performance and emission characteristics are measured using an Exhaust gas analyzer, smoke meter, piezoelectric pressure transducer and crank angle encoder for different fuel blends (Diesel, B10, B20 and B30) and engine load conditions. Fuzzy logic model uses triangular and trapezoidal membership function because of its higher predictive accuracy to predict the engine performance and emission characteristics. Computational results clearly demonstrate that, the proposed fuzzy model has produced fewer deviations and has exhibited higher predictive accuracy with acceptable determination correlation coefficients of 0.99136 to 1 with experimental values. The developed fuzzy logic model has produced good correlation between the fuzzy predicted and experimental values. So it is found to be useful for predicting the engine performance and emission characteristics with limited number of available data.

• 국제물리치료학회지
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• 제9권4호
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• pp.1602-1607
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• 2018

This study examined the correlation between power error (PE) and velocity error (VE) according to the condition and frequency of self-controlled feedback (SCF) during knee extension. One hundred participants were randomly assigned to 30% SCF, 70% SCF, 30% yoked feedback (YF), 70% YF and control group, respectively. The SCF group was provided with feedback when they requested it, whereas the YF group did not influence the feedback schedule. Participants in the control group were not given any visual feedback during the experiment. The isotonic, isometric, and isokinetic dynamometer (PRIMUS RS, BTE, USA) was used to measure the power and velocity error during knee extension. The collected data was analyzed using a Pearson test and SPSS 21.0. The correlation between PE and VE according to the condition and frequency of feedback on each phase during knee extension was significant. Both PE and VE were significantly higher when the feedback was provided with high frequency, passive, and no feedback. Our study suggests that application of SCF can help to improve the proprioception of the healthy person while reducing errors through low frequency and active feedback.

• PNF and Movement
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• 제12권2호
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• pp.63-69
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• 2014

Purpose: The purpose of this study was to investigate the effect that trunk stability exercises with stabilizing reversal and rhythmic stabilization of PNF have on trunk strength and balance ability in stroke patients. Methods: This study included 20 stroke patients who performed trunk stability exercises combined with stabilizing reversal and rhythmic stabilization of PNF. The exercise program consisted of 30-minute sessions per week for six weeks. Trunk strength (BTE, Primus RS) and balance ability (Berg Balance Scale) were evaluated before and after training. All data were analyzed using SPSS 18.0 software. Results: Significant differences were observed the both groups for truck strength and balance ability. The results of the study were as follows: trunk strength was significantly increased in both groups (p<.05) and it was also found to be significant between groups after the intervention (p<.05). Balance ability was significantly increased in both groups (p<.05) and it was also found to be significant between the groups after intervention (p<.05). Conclusion: Trunk stability exercises with stabilizing reversal and rhythmic stabilization of PNF are effective for improving trunk strength and balance ability in stroke patients. For stroke patients, trunk stability exercises with PNF are very useful and effective and they areeffectiveinclinicalpractice.

• 한국분무공학회지
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• 제28권2호
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• pp.55-61
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• 2023

Natural gas is a high-octane fuel that is effective in controlling knocking combustion. In addition, as a low-carbon fuel with a high hydrogen-carbon ratio, it emits less carbon dioxide and almost no particulate matter compared to conventional fossil fuels. Stoichiometric combustion engines equipped with a three-way catalyst are useful in various fields such as transportation and power generation because of their excellent exhaust emission reduction performance. However, stoichiometric combustion engines have a disadvantage of lower thermal efficiency compared to lean combustion engines. In this study, a combination of high compression ratio and Atkinson cycle was implemented in a 11 liter, 6-cylinder, spark-ignition engine to improve the thermal efficiency of the stoichiometric engine. As a result, pumping and friction losses were reduced and the operating range was extended with optimized Atkinson camshaft. Based on the exhaust gas limit temperature of 730℃, the maximum load and thermal efficiency were improved to BMEP 0.66 MPa and BTE 35.7% respectively.

• International Journal of Automotive Technology
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• 제6권1호
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• pp.15-21
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• 2005

The purpose of this paper is to experimentally investigate the engine pollutant emissions and combustion characteristics of diesel engine fueled with ethanol-diesel blended fuel (bio-diesohol). The experiments were performed on a single-cylinder DI diesel engine. Two blend fuels were consisted of $15\%$ ethanol, $83.5\%$ diesel and $1.5\%$ solublizer (by volume) were evaluated: one without cetane improver (E15-D) and one with a cetane improver (E15-D+CN improver). The engine performance parameters and emissions including fuel consumption, exhaust temperature, lubricating oil temperature, Bosch smoke number, CO, NOx, and THC were measured, and compared to the baseline diesel fuel. In order to gain insight into the combustion characteristics of bio-diesohol blends, the engine combustion processes for blended fuels and diesel fuel were observed using an Engine Video System (AVL 513). The results showed that the brake specific fuel consumption (BSFC) increased at overall engine operating conditions, but it is worth noting that the brake thermal efficiency (BTE) increased by up to $1-2.3\%$ with two blends when compared to diesel fuel. It is found that the engine fueled with ethanol-diesel blend fuels has higher emissions of THC, lower emissions of CO, NOx, and smoke. And the results also indicated that the cetane improver has positive effects on CO and NOx emissions, but negative effect on THC emission. Based on engine combustion visualization, it is found that ignition delay increased, combustion duration and the luminosity of flame decreased for the diesohol blends. The combustion is improved when the CN improver was added to the blend fuel.

• 한국자동차공학회논문집
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• 제22권5호
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• pp.59-65
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• 2014

Diesel engines have the superior combustion efficiency and fuel economy that they are widely used for industry, heavyduty vehicles, etc. However, its exhaust emissions have become the major concerns due to their environmental impacts. Moreover, the depletion of fossil fuels is the main issue. Therefore, it is important to look for alternative sources of energy. Bio-diesel is one of the ideal energy which has proved to be ecofriendly for more than fossil fuels. The experimental tests analysed the engine performance and emission characteristics of a diesel engine using diesel and biodiesel blended of BD25, BD45 and BD65, in order to study the use of clean fuel to meet the increasingly stringent emission regulations. The engine performance was examined by using engine dynamometer while an exhaust gas analyzer was used to examine the emission characteristics. The effect of biodiesel on engine performance were lower to diesel through comparing their HP and torque but fuel consumption was slightly increased because of biodiesel has lower heating value and higher density than diesel. However, due to the better lubricity, the brake thermal efficiency of biodiesel was higher than diesel. The emission characteristics were strongly affected by the blending ratio of diesel and biodiesel. The results showed that the smoke opacity, hydrocarbons (HC) and carbon monoxide (CO) emissions decreased while the nitrogen oxides (NOX) slightly increased.

• 대한물리의학회지
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• 제12권4호
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• pp.83-92
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• 2017

PURPOSE: The purpose of this study was to investigate the effect of the elastic band and stretching exercise program on ankle joint maximal voluntary isometric contraction (MVIC) and plantar pressure in high-heel wearing women in their 20s. METHODS: Twenty women in their twenties were randomly assigned to the experimental group (n=10) and the control group (n=10). The experimental group (n=10) performed the elastic band exercise program, while the control group (n=10) performed the stretching exercise program. Both exercise programs were performed three times a week for a total of four weeks. The BTE Primus RS was used in order to measure the ankle joint MVIC during dorsiflexion, plantar flexion, inversion, and eversion. Maximum pressure ($N/cm^2$), average pressure ($N/cm^2$) were measured using the Pedoscan. SPSS v. 21.0 software was used for all statistical analyses in this study. RESULTS: The measurement of the ankle joint's MVIC revealed that in inversion, a significant change in both feet was seen in both the experimental and control groups. In eversion, there was a significant change in both feet only in the experimental group. In terms of the rest of the results, no significant changes were visible. With regard to the plantar pressure, no significant results were seen for either foot in the comparison between or within the groups. CONCLUSION: Exercise program using elastic band and exercise program using stretching were effective on MVIC of ankle joint muscles, although it had no effect on changes of plantar pressure.

• 한국멀티미디어학회논문지
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• 제10권4호
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• pp.450-461
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• 2007

본 논문에서는 묵음 억제 기술이 지원되는 VoIP 트래픽에 비 실시간 트래픽을 위한 전원 절약 모드와 실시간 트래픽을 위한 전원 절약 모드를 동시에 적용하는 혼합 전원 절약 모드를 제안한다. 제안한 방법은 사용자들이 통화를 하고 있는 구간에서는 제 2종 전원 절약 모드를 적용하고 상호 침묵 구간에서는 BTE(binary truncated exponent) 알고리즘 혹은 PSID (probabilistic sleep interval decision) 알고리즘을 적용하여 휴지 구간 (sleep interval)의 길이와 위치를 결정한다. 제안한 알고리즘의 성능을 평가하기 위하여 평균 버퍼링 지연 시간, 단말의 에너지 소비 효율, VoIP 패킷의 손실률 등을 고려한다. 시뮬레이션 결과로부터 혼합전원 절약 모드는 VoIP서비스의 최대 허용 패킷 손실률을 만족시키면서 단말의 에너지 소비를 제 2종 전원 절약 모드보다 25%까지 낮출 수 있다는 것을 보여준다.

• 한국컴퓨터정보학회논문지
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• 제14권10호
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• pp.1-10
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• 2009

현대의 프로세서 아키텍처에서 정확한 분기 예측은 시스템의 성능에 지대한 영향을 끼친다. 최근의 연구들은 예측 정확도뿐만 아니라, 예측 지연시간 또한 성능에 막대한 영향을 끼친다는 것을 보여준다. 하지만, 예측 지연시간은 간과되는 경향이 있다. 본 논문에서는 분기 예측지연시간을 극복하기 위한 분기 선예측 기법을 제안한다. 이 기법은 분기장치를 인출 단계에서 분리함으로써, 분기 예측기가 명령어 인출 장치로부터의 아무런 정보도 없이 스스로 분기 예측을 진행 가능하게 한다. 또한, 제안된 기법을 지원하기 위해, BTB의 구조를 새롭게 개선하였다. 실험 결과는 제안된 기법이 동일한수준의 분기 예측정확도를 유지하면서, 대부분의 예측지연시간을 은폐한다는 것을 보여준다. 더욱이 제안된 기법은 항상 1 싸이클의 예측 지연시간을 가지는 이상적인 분기 예측기를 사용한 경우보다도 더 나은 성능을 보여준다. 본 논문의 실험 결과에 따르면, 기존의 방식과 비교했을 때, 최대 11.92% 평균 5.15%의 IPC 향상을 가져온다.