• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2000년도 가을 학술발표회 논문집
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• pp.201-208
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• 2000

In this study, the behavior of saturated sandy soils under dynamic loads - pore water pressure and effective stress - was investigated using Disturbed State Concept(DSC) model. The model parameters are evaluated from laboratory test data. During the process of loading and reverse loading, DSC model is utilized to trace strain-hardening and cyclic softening behavior. The procedure of back prediction proposed in this study are verified by comparing with laboratory test results. From the back prediction of pore water pressure and effective mean pressure under cyclic loading, excess pore water pressure increases up to initial effective confining pressure and effective mean pressure decrease close to zero in good greement with laboratory test results. Those results represent the liquefaction of saturated sandy soils under dynamic loads. The number of cycles at initial liquefaction using the model prediction is in good agreement with laboratory test results. Therefore, the results of this study state that the liquefaction of saturated sandy soils can be explained by the effective tress analysis.

• 소성∙가공
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• 제30권1호
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• pp.35-42
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• 2021

Magnesium alloys are used in electronic devices such as laptops due to their lightweight features as well as vibration absorption and electromagnetic shielding properties. However, the precision of electronics is limited by the large number of small and precise ribs, the cost-effective manufacture of which requires appropriate technology. Plate forging is an efficient manufacturing process that can address these challenges. In this study, plate forging of magnesium alloys was investigated specifically for the fabrication of laptop cover. The plate forging process with back-pressure was used for near-net shape formation. Finite element analysis was used to select appropriate variables for back-pressure formation to generate ribs of various sizes and shapes without defects. The reliability of the analysis was verified to manufacture the prototype. The effect of back-pressure can be verified via fabrication of prototypes as well as structure and forming analysis based on finite element method. The process design factor of back-pressure increases formability without defects of under-filling and flow-through. Moreover, the tensile strength was maintained even after high temperature plate forging at 370 ℃, and the elongation was improved.

• The Journal of Korean Physical Therapy
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• 제26권1호
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• pp.21-26
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• 2014

Purpose: This study examined the effect of trunk stabilization exercise upon the lumbar stabilization and foot pressure on an unstable surface with back pain. Methods: The subjects of the study were 10 patients who showed the symptom of back pain with excessive lumbar curve. This study was 4 weeks, 30 minutes per session, three times a week for a total of 12 times as a result of exercise radiation imaging device and foot pressure analyzer. Results: The sacrohorizontal angle was statistically significant(p<0.05). Comparison of the difference between static right and left foot pressure ratio analysis was statistically significant(p<0.05). Dynamic right and left foot pressure comparisons for the difference was statistically significant in the analysis (p<0.05). Conclusion: Trunk stabilization exercise and the reduction of the excessive sacrohorizontal angle, and static and dynamic foot pressure imbalance reduced left and right.

• Asian Pacific Journal of Cancer Prevention
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• 제16권18호
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• pp.8127-8133
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• 2016

Background: The objective of this study was to evaluate the effect of back massage on the anxiety state, cortisol level, systolic/diastolic blood pressure, pulse rate, and sleep quality in family caregivers of patients with cancer. Materials and Methods: Forty-four family caregivers were randomly assigned to either the experimental or control group (22 interventions, 22 controls) after they were matched on age and gender. The intervention consisted of back massage for 15 minutes per day for a week. Main research outcomes were measured at baseline (day I) and follow-up (day 7). Unpaired t-test, paired t test and chi-square test were used to analyse data. Results: The majority of the caregivers were women, married, secondary school educated and housewife. State anxiety (p<0.001), cortisol level (p<0.05), systolic/diastolic blood pressure (p<0.001, p<0.01 respectively), and pulse rate (p<0.01) were significantly decreased, and sleep quality (p<0.001) increased after back massage intervention. Conclusions: The study results show that family caregivers for patients with cancer can benefit from back massage to improve state anxiety, cortisol level, blood pressure and heart rate, and sleep quality. Oncology nurses can take advantage of back massage, which is non-pharmacologic and easily implemented method, as an independent nursing action to support caregivers for patients with cancer.

• 기본간호학회지
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• 제18권3호
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• pp.348-355
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• 2011

Purpose: This study was done to examine the effects of heat therapy on low back pain, blood pressure and pulse rate after percutaneous coronary intervention. Method: The participants in this study were 40 patients who were admitted after having percutaneous coronary intervention. The experimental group, 20 patients, had heat therapy and the control group, 20 patients, maintained a supine position for 12 hours after the intervention. Back pain (VAS), blood pressure and pulse rate were measured just after removal of the sheath, and at 2-hour intervals up to 6 hours. Data were analyzed using SPSS 15.0. Results: The experimental group had significantly lower VAS for low back pain (F=23.44, p=.001). However no significant differences were found between two groups for blood pressure and pulse rate. Conclusion: The findings indicate that heat therapy is effective in reducing low back pain in patients who have had percutaneous coronary intervention. Therefore, heat therapy could be used as nursing intervention percutaneous coronary intervention.

• 한국의류학회지
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• 제27권5호
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• pp.485-495
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• 2003

This study was to compare and analyze the clothing pressure according to arms movements of 4 brands jacket for middle-aged women group by measuring clothing pressure of each brand. The results were as follows: 1. According to the analysis of jackets of 4 brands, in general, jacket C had the largest ease amount. while jacket A had a large ease amount in waist, hip areas compared with bust area. Also jacket B had a small ease amount in bust, waist areas and jacket D had a small ease amount in hip areas. Therefore the ease amount is different between each brand, each size even though jacket designs are similar. 2. It was found that clothing pressure was affected by arm movements than jackets. Since this study was limited to the arm movement for motion variation, it was recognized that a significant difference among each jacket and each movement at shoulder, waist parts existed with relation to this motion. 3. Parts showing a significant difference among each size were bust point, abdomen point, center back point of abdomen level, angulus superior scapulae point and center back point of waist level. Also clothing pressure of size B91 was bigger than size B88 except Center back point of waist level. 4. Clothing pressure in shoulder point, front armpit point, back armpit point, upper arm point areas increased as the angle of the arms movement increased. Also, individual variation of clothing pressure in front armpit point, back armpit point, armpit point and upper arm point was large, and clothing pressure in abdomen point was high in M5(sitting posture).

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.830-835
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• 2004

In railway systems, the performance of turnout is one of the most important factors to improve the train's speed. Standard turnout, in which one track is split in main track side and turnout side. Because the main track side remains linear, speed restriction can be alleviated while train pass the main track side. The factors of speed restriction in main track side are strength of crossing and tongue rail, wheel back side pressure of guard rail and wing rail. In this study, we measured wheel back side pressure of guard rail to compare improved turnout with present turnout. In result, the wheel back side pressure of improved turnout was lower than present turnout, so its performance was proved.

• 한국연소학회지
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• 제4권1호
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• pp.117-129
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• 1999

A method for the mixing augmentation of the transverse injection of fuel in a Scramjet combustor is suggested. Based on the fact that the main factor controlling the mixing characteristics in transverse injection is the effective back-pressure (the pressure around the injection hole) it is tried to make a flow expansion near the injection port in order to reduce effective back-pressure. A three dimensional Navier-Stokes code adopting the upwind method of Roe#s flux difference splitting scheme is used. The k-w SST turbulence model turbulence model is used to calculate the turbulent viscosity. It is shown that the reducing of the effective back-pressure make it possible to increase the penetration distance and to increase the mixing rate without excessive losses of stagnation pressure. Also, it is shown that the streamwise vorticity generated by baroclinic torque has great influences on the mixing process.

• 한국분무공학회지
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• 제3권2호
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• pp.24-33
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• 1998

The characteristics of liquefied butane spray are expected to be different from conventional diesel fuel spray, because a kind of flash boiling spray is expected when the back pressure is below the saturation vapor pressure of the butane(0.23MPa at $25^{\circ}C$). An accumulator type pintle injector and its fuel delivery system has been simulated in ruder to give injection pressure, needle lift and rate of fuel injected. The governing equation were solved by finite difference metho. The injection duration was controlled by solenoid valve. Spray behaviors such as a transient spray tip penetration, spray angle and SMD were calculated based on the empirical correlations in case that the back pressure is both above the vapor pressure of the butane and below that of butane. When the back preassure is below the vapor pressure of the fuel, conventional correlation is modified to represent the effect of flash boiling.

• 한국추진공학회지
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• 제19권5호
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• pp.31-36
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• 2015

이중 모드 스크램제트 엔진은 미래 가장 촉망받는 시스템 중 하나로, 많은 연구자들에게 각광받고 있다. 이중 모드 스크램제트 엔진 시스템에서 격리부와 관련된 유동 특징들은 중요한 역할을 한다. 본 연구에서 풍동을 가진 이중 모드 스크램제트 엔진을 조사하기 위해 2차원 수치해석을 수행하였다. 계산방법의 타당성을 검증하기 위하여 실험결과와 비교하였으며, 수치해석 결과는 실험값과 비교하여 전체적으로 압력 분포가 잘 일치하였다. 배압은 최대 압력 상승을 분석하기 위해 연구되었다. 그 결과 초음속 흡입구 영역의 압력 분포는 배압에 영향을 받지 않았으며, 배압이 증가함에 따라 Shock train은 상류 쪽으로 밀려나갔다. 격리부의 길이가 증가함에 따라 최대 배압값은 입구 불시동 없이 급격히 증가한 후 일정하게 유지되었으며, 격리부 영역의 최적 길이($L/H_{th}$)는 8.7이다.