• 한국자동차공학회논문집
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• 제16권4호
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• pp.151-158
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• 2008

Gasoline Homogeneous Charge Compression Ignition (HCCI) combustion is a new combustion concept. Unlike the conventional internal combustion engine, the premixed fuel mixture with high residual gas rate is auto-ignited and burned without flame propagation. There are several operating factors which affect HCCI combustion such as start of combustion (SOC), residual gas fraction, engine rpm, etc. Among these factors SOC is a critical factor in the combustion because it affects exhaust gas emissions, engine power, fuel economy and combustion characteristics. Therefore SOC of gasoline HCCI should be controlled precisely, and SOC detection should be preceded SOC control. This paper presents a control oriented SOC detection method using 50 percent normalized difference pressure. Normalized difference pressure is defined as the normalized value of difference pressure and difference pressure is difference between the in-cylinder firing pressure and the motoring pressure. These methods were verified through the HCCI combustion experiments. The SOC detection method using difference pressure provides a fast and precise SOC detection.

• 센서학회지
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• 제22권3호
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• pp.227-232
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• 2013

In this research, fiber-optic pressure sensors were fabricated with rugate-structured porous silicon (RPS) diaphragms coated with PMMA (Polymethyl-Methacrylate). The reflectance spectrum of the PMMA/RPS diaphragm was almost the same as that of uncoated RPS diaphragm. However the mechanical strength of the PMMA/RPS diaphragm increased more than that of the uncoated diaphragm. As a result, the fiber-optic sensor fabricated with PMMA/RPS diaphragm could successfully detect more high pressure difference without diaphragm damage than the highest detectable pressure difference of the sensor with normal RPS diaphragm. The response data of the fiber-optic sensor recorded as a function of pressure difference were fitted by theoretical curves. During this process, elastic moduli of the used PMMA/RPS diaphragms were obtained numerically. The dynamic response properties of the fiber-optic sensor were also investigated under continuous variation of the pressure difference conditions.

• 대한통합의학회지
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• 제1권2호
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• pp.37-46
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• 2013

Purpose : The purpose of the research was to analyze foot pressure, foot temperature, and correlation between foot pressure and foot temperature to grasp impact on foot pressure and body temperature distribution chart depending on functional difference of leg length. Method : After measuring leg length, put 15 students whose functional difference of leg length was over 10mm to difference group and 15 students whose functional difference of leg length was under 5mm to normal group and categorize soles of foot into 6 sections of hallux head, 1st metatarsal head, 2-4 metatarsal head, 5 metatarsal head, lateral heel, and then measure by foot pressure analyzer to analyze characteristic of pressure distribution and classify into front of the lower leg, back of the lower leg, soles of foot and measure by body temperature analyzer to analyze by checking body temperature. Result : Weight difference depending on foot pressure and body temperature was bigger when functional difference of leg length was bigger, and it could be confirmed that foot pressure and body temperature of short leg side were higher than those of short leg side. Thus, if difference exists in leg length, weight load on short leg side increases which results in higher foot pressure and body temperature, therefore enabling an assumption that mechanical problem will occur in short leg. Conclusion : When functional leg length inequality, weight bearing and pressure was getting high as a result, temperature was getting high in short leg.

• 한국수소및신에너지학회논문집
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• 제20권5호
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• pp.390-396
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• 2009

The flooding, especially in channel, is one of the critical issue to put proton exchange membrane fuel cell (PEMFC) to practical use. In this paper, channel flooding was investigated the pressure difference at cathode channel outlet. A ratio of pressure difference changes to 25, 50% as its variation rate. The pressure variable rate is reflected in dimensionless number FN. As a result, modified dimensionless number $FN^*$ correctly predicted the channel flooding. This study analyzes that a variety of pressure difference is how to affect flooding at the cathode of the PEMFC.

• 대한물리의학회지
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• 제6권2호
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• pp.199-205
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• 2011

Purpose: The purpose of this study was to investigate the effect of 0cm, 2.5cm, 5cm height increase elevator shoes insole on gait and foot pressure Methods: Fifteen young adult were recruited this study. Gait and foot was measured by Gait AnalyzerTM(Tech Storm Inc. korea). Statistical analysis was used one-way ANOVA to know difference between 0cm, 2.5cm insole and 5cm insole Results: There was no significantly difference on foot length, foot width, foot angle, step time during gait. But step length and step width was significantly difference during gait. There was no significantly difference on gait ratio during stance phase. There was significantly difference on forefoot pressure and rearfoot pressure ratio. Conclusion: These results indicate that height increase elevator shoes insole may be caused step length, step width decreaseed during gait. It caused forefoot pressure increased and rearfoot pressure decreased on foot.

• 대한정형도수물리치료학회지
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• 제24권1호
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• pp.67-75
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• 2018

Background: The purpose of this study was to investigate the effect of pressure distribution on the both foots with gluteus medius muscle intensive strengthening exercise in 4week. Methods: The purpose of this study was to investigate the effect of gluteus medius muscles strengthening exercise on the pressure distribution of the foot in 20 healthy adults. Four gluteus medius muscles strengthening exercise programs were conducted three times a week for four weeks. The pressure distribution changed of the right and left foot parts of the experimental group and the control group were measured and analyzed. Results: There was a significant difference in F1, F2, M1, M2, and H1 among the pressure distribution of the right foot of the experimental group (p<.05). There was a significant difference in F1, M1, M2, H1 and H2 among the pressure distributions of the left foot of the experimental group (p<.05). There was a significant difference in H1 among the pressure distribution of the right foot of the control group (p<.05). There was no significant difference in the pressure distribution of the left foot region of the control group (p>.05). There was a significant difference in H1 among the pressure distribution of the right foot between the group (p<.05). There was a significant difference in M2, H1 among the pressure distribution of the left foot between the group (p<.05). Conclusions: In the healthy adults, it was confirmed that the application of the gluteus medius muscles strengthening exercise had an effect on the weight shift during the walking due to the overall foot balance and the pressure distribution change of the foot part.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.111-112
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• 2020

As buildings in South Korea become more skyscrapers, the risk of fire is also emerging. Thus, regulations, regulations, and guidelines are being improved to prevent the spread of smoke in the event of a fire in high-rise buildings, but research on smoke flow and pressure distribution in vertical spaces is insufficient. Therefore, in this study, the temperature of each floor in the vertical space according to the size of the fire is measured through the miniature model experiment, and the pressure difference is calculated to establish the basic data for the improvement of the performance of domestic air supply facilities in the future. Thus, a scale model of one-sixth the size of the actual building was produced to measure the temperature, and the pressure difference was derived by substituting the value for the expression. The pressure difference varies depending on the size of the cause of the fire, and it is believed that the differential pressure and conditions of the building should be taken into account before calculating the supply volume for the analysis of the pressure difference according to the size of the cause of the fire in the event of fire.

• 대한기계학회논문집B
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• 제36권9호
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• pp.915-921
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• 2012

이 연구에서는 실린더 압력과 모터링 압력의 차이인 차이 압력(difference pressure)을 이용하여 IMEP를 추정하는 방법을 제안하고, 추정된 IMEP를 $IMEP_{diff}$로 정의하였다. $IMEP_{diff}$는 차이 압력이 연소 시작 시점에서 연소 종료 시점까지만 존재하는 압력이라는 사실에 기반하여 이론적인 IMEP 계산식의 연산 구간을 최적화한 것으로 IMEP와 비교 시 $R^2$ 0.9955의 높은 선형관계를 보였다. 또한 이론적인 IMEP 계산 방법과 비교하여 21 %의 실린더 압력 데이터 및 31 %의 계산량만으로 IMEP 획득이 가능하여 실시간 제어에 용이하다. $IMEP_{diff}$ 추정 및 제어 성능은 엔진 실험을 통하여 검증하였으며, $IMEP_{diff}$ 제어를 통하여 실린더 간 토크 편차 감소를 확인하였다.

• Korean Journal of Acupuncture
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• 제27권4호
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• pp.59-72
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• 2010

Objectives : In the study on the waveform analysis of radial artery pulse diagnosis, we need to establish fundaments of contemporary pulse diagnosis research, and to find the change of pulse waveform parameter with applied variation pf pressure. Methods : As we will to do experimental research on the difference of pulse waveform on the radial artery with applied variations of pressure(5 stage-pressure) and measuring position(left KWAN). In this research, we analyzed the change of the waveform according to five stage pressure. Results : The results were as follows; When we analyzed the change of the waveform according to pressure in the left KWAN, E, hl, h2 and A were the difference between 8ths pressure grades in 95% trust section. And t2, t4 were the difference between 8ths pressure grades in 95% trust section. W was the difference between 8ths pressure grades in 95% trust section. And h2/h1 was the difference between 6ths pressure grades in 95% trust section. There is the difference between 1st and 2nd grade & between 2nd and 5th grade in the case of t4/t2 in 95% trust section. And there is the difference between 1st and 5th grade, between 3rd and 4th grade, between 3rd and 5th grade & between 4th and 5th grade in the case of W/A in 95% trust section. And there is the difference between 1st and 2nd grade, between 2nd and 3rd grade, between 2nd and 4th grade, between 3rd and 4th grade, between 3rd and 5th grade & between 4th and 5th grade in the case of A/E in 95% trust section. Conclusions : We found the statistically resonable differences between each pulse depending on the applied pressure. And Analysing the radial pulse(left KWAN) at 5 applied pressure levels may be useful to study on the pulse waveform diagnosis.

• PNF and Movement
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• 제19권3호
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• pp.375-382
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• 2021

Purpose: The objectives of the present study were to investigate the disadvantages of tire pressure asymmetry of a wheelchair tire and recommend the criterion for appropriate tire pressure without generating negative changes in the musculoskeletal system in asymptomatic participants. Methods: Fourteen asymptomatic participants were asked to sit in pressure-controlled wheelchairs and perform desk work for 20 minutes in each tire condition. The asymmetry of the tire conditions was set as 0% difference, 25% difference, and 50% difference from the recommended pressure. The pelvic alignment and muscular recruitment represented as a flexion-relaxation ratio (FRR) were measured at pre-test, and after each condition of desk work. The displacement of the center of pressure (COP) was measured during the desk work. Results: The tire air pressure condition significantly affected the FRR and COP (P < 0.05). Both sides of the FRR values were significantly higher under the symmetrical tire conditions (0% difference) and pre-test, compared with the asymmetrical tire condition of 50% difference (P < 0.05). The mediolateral COP displacement of the asymmetrical tire conditions (25% and 50% difference) was significantly higher than that of the symmetrical tire conditions (0%) (P < 0.05). Conclusion: Asymmetrical tire conditions could cause changes in the muscle recruitment pattern of the erector spine and mediolateral COP displacement. Tire pressure asymmetry higher than 50% could be a risk factor for prevalence of back pain, so this level of asymmetry in tire pressures should be cautioned against for wheelchair users.