• Journal of Chest Surgery
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• 제17권3호
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• pp.339-345
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• 1984

Thirty four patients with a ventricular septal defect, aged 2 months to 24 years [median 2.33 years], had lung biopsies during open heart procedures to assess the degree of pulmonary vascular disease. The patients were divided into two groups according to their age; group 1 - under 2 years of age [15 patients], and group 2- over 2 years of age [19 patients]. The, pathologic change of the pulmonary arterioles was correlated with pre-operative hemodynamic data in 34 patients. There was no significant correlation between the severity of pulmonary vascular disease according to Heath-Edwards classification and the patients age [X2=1.8381, P=0.1751 ]. There was a significant correlation between degree of medial wall thickness and arteriolar diameter and the level of preoperative peak pulmonary artery pressure and peak systemic artery pressure [Pp/Ps]. Also, there was a good correlation between the preoperative pulmonary vascular resistance and systemic vascular resistance [Rp/Rs]. There was no significant correlation between wall thickness and Pp/Ps, and Rp/Rs below the age of 2 years. We conclude that, in patients over 2 years of age, there was a significant correlation between the medial wall thickness of the pulmonary arteriole and elevation of Pp/Ps and Rp/Rs. This is not true in patients under 2 years of age.

• Wind and Structures
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• 제21권2호
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• pp.119-158
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• 2015

The characteristics of the coherence functions of X axial, Y axial, and RZ axial (i.e., body axis) wind forces on the Shanghai World Trade Centre - a 492 m super-tall building with section varying along height are studied via a synchronous multi-pressure measurement of the rigid model in wind tunnel simulating of the turbulent, and the corresponding mathematical expressions are proposed there from. The investigations show that the mathematical expressions of coherence functions in across-wind and torsional-wind directions can be constructed by superimposition of a modified exponential decay function and a peak function caused by turbulent flow and vortex shedding respectively, while that in along-wind direction need only be constructed by the former, similar to that of wind speed. Moreover, an inductive analysis method is proposed to summarize the fitted parameters of the wind force coherence functions of every two measurement levels of altitudes. The comparisons of the first three order generalized force spectra show that the proposed mathematical expressions accord with the experimental results well. Later, the influences of coherence functions on wind-induced dynamic responses are analyzed in detail based on the proposed mathematical expressions and the frequency-domain method of random vibration theory.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 F
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• pp.2780-2782
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• 1999

Many electronic ballasts for low pressure discharge lamps as fluorescent lamps are produced and commercialized. However, the electronic ballasts for high pressure lamps are now in progress to because of poor reliability and high cost of production. To obtain the confidence of electronic ballasts, it is necessary to prolong the life time of output switches. A variable frequency driver for inverter switches that can control the magnitude of output current with temperature of switches was designed and simulated. A conditions for circuit design are 22kHz : standard frequency, $100^{\circ}C$: standard temperature, $I_{peak}$ : 0.76A, and $V_{peak}$ : 184V, respectively. By simulation, as the temperature exceed a standard temperature, the frequency was increased up to 40kHz. However, the current and voltage that flow through switchs were decreased to 0.507A and 121V at $150^{\circ}C$, respectively.

• 설비공학논문집
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• 제21권8호
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• pp.448-455
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• 2009

A performance analysis of the regenerative gas turbine system with afterfogging is carried out. Because of the high temperature at the outlet of air compressor, afterfogging has a potential of improved recuperation of exhaust heat than inlet fogging. Thermodynamic analysis model of the gas turbine system is developed by using an ideal gas assumption. Using the model, the effects of pressure ratio, water injection ratio, and ambient temperature are investigated parametrically on thermal efficiency and specific power of the cycle. The dependency of pressure ratio giving peak thermal efficiency is also investigated. The results of numerical computation for the typical cases show that the regenerative gas turbine system with afterfogging can make a notable enhancement of thermal efficiency and specific power. In addition, the peak thermal efficiency is shown to decrease almost linearly with ambient temperature.

• 한국소음진동공학회논문집
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• 제24권3호
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• pp.205-212
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• 2014

이 연구에서 현대자동차의 단순실험모델(HSM)에 대한 썬루프 버페팅에 대한 수치해석이 수행되었다. 검증을 위하여 HSM 목부위의 경계층에 대한 속도분포 해석결과를 실험결과와 비교하였다. 썬루프 해석은 두 단계로 이루어졌다. 첫 번째로 난류 RANS 모델을 이용하여 정상상태 해석이 수행되었으며, 해석결과는 CAA++의 입력값으로 사용된다. 두 번째 단계는 유동속도에 대한 1차 최대 압력피크와 버페팅 주파수 해석을 위한 비정상상태 해석이 CAA++에서 이루어졌다. 주파수와 음향압력의 수치해석 결과는 타당한 물리적 현상을 보여주고 있으며, 현대 자동차의 실험결과와 잘 일치하는 결과를 보여주었다.

• 지역사회간호학회지
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• 제19권1호
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• pp.46-56
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• 2008

Purpose: The purpose of this study was to identify the effects of pelvic floor muscle exercise on reducing the symptoms of stress urinary incontinence and improving attitude toward exercise and quality of life. Method: The research adopted was a nonequivalent control group pretest posttest design. The subjects were 55 persons who were surveyed using a structured questionnaire, and 23 persons in the experimental group among the total sample were measured for the peak pressure and the duration of PMC and trained correct pelvic floor muscle contraction using peritron in the first week. Then, pelvic floor muscle exercise was implemented for 6 weeks. The data was analyzed by $\chi^2$-test and t-test with the SPSS 10.0 program. Results: 1) The degree of stress urinary incontinence, frequency of urination, nocturia, urgency, noctural incontinence, the frequency and quantity of incontinence, outer clothing change and incomplete emptying decreased significantly more in the experimental group than in the control group. 2) Attitude toward pelvic floor muscle exercise and the qualify of life were improved significantly more in the experimental group than in the control group. 3) The peak pressure and duration of PMC increased significantly more in the posttest. Conclusion: Based on the results above, it is judged that pelvic floor muscle exercise is an effective nursing intervention in order to care for stress urinary incontinence.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 춘계 학술대회논문집
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• pp.1-14
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• 1998

Underwater explosion properties for TNT, an ideal explosive, and DXD-04, a nonideal explosive, were numerically modeled with a one-dimensional Lagrangian hydrodynamic code. The equation of state parameters for detonation products for TNT and DXD-04 were obtained from the BKW code, assuming complete reaction. Burn of TNT was modeled by using the Chapman-Jouguet(CJ) volume burn technique, a programmed-burn technique, assuming instantaneous detonation reaction. Burn of DXD-04 was modeled by using the same technique and by using the reaction rate calibrated from two-dimensional steady-state detonation experiments. The calculations for TNT reproduced the experimental peak pressure of the shock wave propagating through water with an error of $3.0\%$ and the experimental oscillation period of the bubble formed of detonation products with an error of $2.3\%$. For DXD-04, the CJ volume burn technique could not reproduce the experimental observations. When the reaction rate calibrated from two-dimensional steady-state detonation experimental data, the calculated peak pressure was slightly higher by $7.3\%$ than the experimental data, but the calculated shock profile was in good agreement. The bubble period was reproduced with an error of $1.8\%$. These results demonstrated that underwater explosion properties for an ideal explosive can be predicted by using a programmed burn technique, and that, however, those for a nonideal explosive can be predicted only when a well-calibrated reaction rate is used.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1998년도 추계학술대회
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• pp.125-126
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• 1998

Pulse conduction velocity is determined by areterial compliance, which is changed by lateral pressure of arterial wall. Hydrostatic pressure of the limb vessel is changed by body position, especially in elevated arm. The arterial pulse in the finger causes the blood volume to change, changing the optical density of the blood. Photoplethysmograph of index finger was obtained by LED and phototransistor. Pulse transmission time(PTT) was measured by the interval between the peak of ECG R wave and the peak of the finger plethysmogram. PTT was increased by upward position of arm, and decreased by downward position of the arm compared to horizontal position. This result suggests that relationship between finger plethysmography and postural change could be applied to evaluate clinical cardiovascular status.

• Korea-Australia Rheology Journal
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• 제20권4호
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• pp.253-260
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• 2008

A method based on transient shear flow dynamics of red cell aggregates was developed to investigate reversible re-aggregation processes with decreasing shear flow. In the microchannel-flow aggregometry, the aggregated red blood cells that are subjected to continuously decreasing shear stress in microchannel flow were measured with the use of a laser-scattering technique. Both the laser-backscattered intensity and pressure were simultaneously measured with respect to time, resulting in shear stress ranging from $0{\sim}35\;Pa$ for a time period of less than 30 seconds. The time dependent recording of the backscattered light intensity (syllectogram) yielded an upward convex curve with a peak point, which reflected the transition threshold of aggregation in the RBC suspensions. Critical-time and critical-shear stress corresponding to the peak point were examined by varying the initial pressure-differential and the micro channel depth, and these results showed good potential for being used as new aggregation indices. In the present study, these newly proposed indices were also validated by differentiating the effect of fibrinogen on RBC aggregation and then these indices were compared to the conventional indices that were measured by a rotational aggregometer.

• 한국의류산업학회지
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• 제2권5호
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• pp.398-404
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• 2000

We examined the effect of individual sweating responses on thermoregulatory responses induced by heat of sorption, immediately after the onset of sweating. The present study consists of two experiments. In experiment 1, made of 100% cotton (C) and 100% polyester (P) clothing were exposed in the chamber at ambient temperature (Ta) of $27.2^{\circ}C$ and relative humidity (rh) raised from 50% to 95% at five different increase rates of environmental vapor pressure (VP). The increase rate of clothing surface temperature (Tcs), peak Tcs and peak time showed significant correlation with the increase rate of environmental VP in C-clothing (p<0.05). In experiment 2, seven female subjects were studied during leg water immersion ($35-41^{\circ}C$) for 70min in Ta of 27.2 and 50%rh. There were significant positive correlations in the increase rate of clothing microclimate VP vs. changes in Tcs, skin blood flow, mean skin temperature and mean body temperature (p<0.05). The present results showed that individual clothing microclimate VP had significant effects on thermoregulatory responses induced by heat of sorption wearing C ensembles.