• 동력기계공학회지
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• 제10권4호
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• pp.38-42
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• 2006

Pressure drops and friction factors in square channels with twisted tape inserts plus axial interrupted ribs are investigated. Tests are performed for Reynolds numbers ranging from 8,900 to 29,000. The rib height-to-channel hydraulic diameter, $e/D_h$, is kept at 0.057 and test section length-to-hydraulic diameter, $L/D_h$ is 30. The pressure drops and friction factor values are enhanced with axial interrupted ribs and twisted tape inserts. Square channels with twisted tape inserts plus axial interrupted ribs show the greatest pressure loss penalty in the present work. Friction factor data obtained for the square channel with twisted tape inserts plus axial interrupted ribs are less than those in the past publications for circular tubes with axial interrupted ribs and twisted tape inserts.

• 설비공학논문집
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• 제19권3호
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• pp.220-227
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• 2007

Heat transfer and momentum transfer under conditions of both oscillating flow and oscillating pressure within pulse tubes show very different behavior from those for steady state conditions. The analytic solutions of axial velocity and temperature of the gas within pulse tubes were obtained by assuming that the variations in pressure and temperature were purely sinusoidal and small. The shear stress and the heat flux at the tube wall obtained from the solutions are expressed in terms of the cross-sectional averaged velocity, the difference between mean temperature and instantaneous cross-sectional averaged temperature and the difference between mean pressure and instantaneous pressure. It is shown that the complex shear factor, which has been applied to momentum transfer of incompressible oscillating flow, and the complex Nusselt number, which has been applied to either heat transfer with oscillating pressure only or heat transfer of incompressible oscillating flow, could also be used for momentum transfer and heat transfer subjected to both oscillating flow and oscillating pressure, respectively.

• 대한간호학회지
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• 제14권2호
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• pp.93-111
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• 1984

The main purpose of this study is to develop a ratio scale measuring level of pain using Korean pain terms. The specific purposes of this study are to identify the degree of pain of each pain term in each subclass: to classify each subclass in terms of dimensions of pain; and to analyze factors of the Korean pain ratio scale clustering together. One hundred an4 fifty eight pain terms which were originally identified as representative terms and their synonyms were used for data collection. Fifty eight nursing professors ana sixty one medical doctors who have contacted with patients having pain were asked to rate the weight of each pain term on a visual analogue scale. Subclasses in which ranks of pain terms were same f s findings in two previous studies were 1) thermal 3 am 2) cavity pressure, 3) single stimulating pain, 4) radiation pain. and 5) chemical pain. Subclasses in which ranks of pain terms were confused were 1) incisive pressure, and 2) cold pain. Subclasses in which one new pain term was added were 1) inflammatory-repeated pain, 2) punctuate pressure, 3) constrictive pressure, 4) fatigue-related pressure, and 5) suffering-relate4 pain. Subclasses in which two new pain terms were added were 1) traction pressure, 2) peripheral nerve pain, 3) dull pain, 4) pulsation-related pain, 5) digestion-related pain, 6) tract pain, and 7) punishment-related pain. Subclass in which 3 new pain terms were included was fear-related pain. Rating scores of 5 words in 4 subclasses were significantly different between the normal group and the extreme group of subjects in terms of subjective rating. Only one word among 6 words was that newly added to the scale. Rating scores of 12 words in 9 subclasses were significantly different between doctor group and nursing professor group. Among these 12 words, only 3 were those newly added to the scale. In comparison of these 12 words, mean scores of the nursing professors were always 7 to 16 points higher than those of the medical doctors. In the analysis of judgement of subjects in terms of dimensions of pain terms, subclasses of dull pain, cavity pressure, tract pain and cold pain were suggested to be included in the miscellaneous dimension. As a result of factor analysis of the ratings given to 96 pain words using principal components analysis without iteration and with varimax rotation limiting the number of factors to 4, factors of severe pain (factor I) mild-moderate pain (factor II) , causative pain (factor III) and temperature-related pain(factor IV) were extracted with the factor loading above 0.388. When the pain words were re-arranged on the bases of factor loading above 0.368, number of factors decreased to only first two factors. Maximum score of pain word in factor II was 46.17 and the minimum score of the factor I was 45.36. Further studies are needed to identify the validity, reliability, sensitivity and practicability of this ratio scale using patients having various sources of pain.

• Geomechanics and Engineering
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• 제6권1호
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• pp.17-31
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• 2014

This paper investigates the development of failure surfaces induced by an embankment on soft marine clay deposits and the characteristics of such surfaces through numerical simulations and its comparative study with monitoring results. It is well known that the factor of safety of embankment slopes is closely related to the vertical loading, including the height of the embankment. That is, an increase in the embankment height reduces the factor of safety. However, few studies have examined the relationship between the lateral movement of soft soil beneath the embankment and the factor of safety. In addition, no study has investigated the distribution of the pore pressure coefficient B value along the failure surface. This paper conducts a continuum analysis using finite difference methods to characterize the development of failure surfaces during embankment construction on soft marine clay deposits. The results of the continuum analysis for failure surfaces, stress, displacement, and the factor of safety can be used for the management of embankment construction. In failure mechanism, it has been validated that a large shear displacement causes change of stress and pore pressure along the failure surface. In addition, the pore pressure coefficient B value decreases along the failure surface as the embankment height increases. This means that the rate of change in stress is higher than that in pore pressure.

• 한국환경생태학회지
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• 제29권2호
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• pp.236-249
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• 2015

The master plan of forest land management proposes forest watershed management that considers regional characteristics in order to overcome the problem of uniform forest land management. In order to manage the forest watersheds in Gyeonggi-do, this study classified 1,823 forest watersheds in Gyeonggi-do and attempted to understand their characteristics. It conducted a factor analysis and cluster analysis from the perspective of conservation value and development pressure using forest land indicators. In terms of conservation value, three factors were drawn: the topography factor, vegetation factor and public service factor, while in terms of development pressure, three factors were drawn: the easiness of development factor, economic benefits factor and development activity factor. Using these factors, forest watersheds were divided into three clusters in terms of conservation value while they were divided into three clusters in terms of development pressure. Using the results of the cluster analysis from a conservation-development perspective, the forest watersheds were classified into nine different types, and the characteristics were identified by each type. It is judged that the factors and clusters drawn as a result of the research accurately reflect the present conditions of Gyeonggi-do, and the nine types of forest watersheds have clear characteristics according to each type, which are judged to be utilized in forest management in the future.

• 대한기계학회논문집
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• 제18권6호
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• pp.1439-1447
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• 1994

Test results of friction-factor for the flow of air in a narrow channel lined with various honeycomb geometries show that, generally, the friction-factor is nearly constant or slightly decreases as the Reynolds number(or Mach number) increases, a characteristic common to turbulent flow in pipes. However, in some test geometries this trend is remarkably different. The friction factor dramatically drops and then rises as the Mach number increases. This phenomenon can be characterized as a "friction-factor jump." Further investigations of the acoustic spectrum indicate that the "friction-factor jump" phenomenon is accompanied by an onset of a normal mode resonance excited coherent flow fluctuation structure, which occurs at Reynolds number of the order of $10^4$. New empirical friction-factor model for "friction-factor jump" cases is developed as a function of Mach number and local pressure.ach number and local pressure.

• Journal of Preventive Medicine and Public Health
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• 제21권1호
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• pp.99-112
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• 1988

1개 의과대학 본과 제 1,2,3학년 279명을 대상으로 1987년 3월중순부터 4월초순에 걸쳐 프레밍헴 A형행동양상척도(FTA)의 신뢰도와 타당도 그리고 사회심리학적인 변수와 혈압과의 관계를 조사해서 다음의 결과를 얻었다. SCL-90-R과 FTA의 신뢰도는 $0.57{\sim}0.91$의 범위였고 FTA의 요인분석에서 정열적경쟁요인(hard-driving competitiveness factor)과 조급요인(impatience factor)이 추출되었다. FTA의 총점은 비교체중이 클수록, 농촌출신이면 높은 경향을 보였으나 유의성은 없었고 SCL90-R과는 우울, 불안, 적대감, 편집증, 정신증하위척도와 비교적 낮은 유의한 정상관관계를 보였다. 혈압과의 단일 변수 분석에서 수축기혈압은 남자에서 비교체중과 가족력이 유의했고 남녀 공히 경제상태에 따른 차이가 있었다. 확장기혈압은 남자에서 비교체중과 음주량이 유의했고 여자에서는 비교체중이 유의한 상관관계를 보였다. 비교 체중의 영향을 제거하고서는 남자에서 음주량이 확장기혈압과 경제상태가 수축기혈압과 유의한 관계를 보였다. 단계적추가분석법에 의한 중회귀분석 결과 남자에서는 수축기혈압에서 비교체중과 경제상태가 중요변수로 선정되었고 확장기혈압에서는 비교체중과 음주량이 선정되었다. Alpha가 0.1수준에서는 수축기혈압에 SCL-90-R의 우울증 하위척도가 추가 선정되었다. 여자에서 수축기혈압은 경제상태와 비교체중이 선정되었고 확장기혈압에서도 비교체중이 선정되었으나 대상자 수가 적어서 불안정했다. FTA와 혈압과는 남녀 공히 관련이 없었다.

• 한국한의학연구원논문집
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• 제16권1호
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• pp.119-134
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• 2010

Objectives & Method：Based on the statistic from January 2008 to December 2008 include 66-year-old 375 people (159 men, 216 women) who got examined in National Health Insurance Corporation, this study set a goal to establish a new health index by analyzing the relation between the cardio-cerebra vascular disease and risk factor such as obesity, smoking, exercise, alcohol consumption, blood pressure, blood sugar and cholesterol. Results：1) Examine results, health status according to gender；People who are diagnosed as abnormal health status have higher risk for both men and women. As for the detailed diseases, high blood pressure was highest followed by hyperlipidemia and obesity. In case of the women, 96.3% in bone mineral density was highest. 2) Correlation of disease and health risk factors based on gender；Correlation of disease according to gender in the obesity(p<0.001), lipid abnormalities(p<0.001), kidney diseases(p<0.001), chest diseases(p<0.05), osteoporosis(p<0.001) showed a statistically significant difference. The analysis showed that the men have more obesity and lipid abnormalities as well as thoracic disease than the women, but the women have more kidney disease than the men. As for the osteoporosis examine which is conducted only for the women, most of the women were abnormal even though it cannot compare the result according to gender. Obesity(p<0.001), alcohol(p<0.001), smoking(p<0.001) and LDLcholesterol(p<0.001) showed statistical correlation between gender and health risk factor. And only high blood pressure(p<0.001) showed a statistical correlation between gender and risk of cardio-cerebra vascular disease. 3) Risk of cardio-cerebra vascular disease related to health risk factor characteristic；Obesity assessment(p<0.001), alcohol(p<0.05), smoking(p<0.05), blood pressure(p<0.001), glucose(p<0.001) showed correlation between health risk factor and stroke. Drinking(p<0.001), smoking(p<0.05), exercise(p<0.001), blood pressure(p<0.001), LDL cholesterol(p<0.001) showed health risk factor and myocardial infarction. Obesity assessment(p<0.001), smoking(p<0.05), blood pressure(p<0.001), glucose(p<0.001) and showed correlation between health risk factor and diabetes. Obesity assessment(p<0.001), blood pressure(p<0.001) showed correlation between health risk factor and high blood pressure. Conclusion：Therefore, we have to take one step farther after the health examination. In order to prevent and reduce the risk of disease, people have to understand their health status exactly first, and correct their habit with recognizing the amount of risk related to cardio-cerebra vascular disease.

• 한국산업보건학회지
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• 제10권1호
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• pp.170-178
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• 2000

Most of manufacturers try to produce the most efficient filter for respirators with the lowest breathing resistance. Filter performance depends on low penetration, i.e., high efficiency (%), and low pressure drop ($mmH_2O$). This study was performed to evaluate performance of respirator filters by quality factor ($q_F$) and suggest the direction for improvement of respirator filters of good quality in Korea. Two mechanical filters, S and K made in Korea, three filtering facepieces, S made in China, C made in Korea and M made in USA, which were widely used in the workplace, were selected and tested efficiency and pressure drop in accordance with flow rate, using with Automated Filter Tester Model 8110 (TSI, USA). The best quality factor within the same respirator filter categories was $0.0672cm^{-1}\;H_2O$ for mechanical filter S, $0.0698cm^{-1}\;H_2O$ for filtering facepiece M at flow rate of 32Lpm. Mechanical filter S would be the best suitable during heavy work since qulity factors decrease less sharply than any others as increased flow rates. It was necessary for mechanical filter S to lower pressure drop without increasing efficiency, but mechanical filter K should be increased efficiency and decreased pressure drop. While filtering facepiece M had the best quality performance of three ones, Sand C should get much higher efficiency and lower pressure for better performance.

• 대한기계학회논문집B
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• 제26권8호
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• pp.1095-1101
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• 2002

An experimental apparatus was prepared to investigate thermal and hydrodynamic characteristics of regenerator at cryogenic temperature under pulsating pressure condition. The regenerator was pressurized and depressurized by a compressor with various operating frequencies. Cold end of the regenerator was maintained around 100 K by means of a liquid nitrogen heat exchanger. Instantaneous gas temperature and mass flow rate were measured at both ends of the regenerator during the whole pressure cycle. Pulsating pressure drop across the regenerator was also measured to see if it could be predicted by a friction factor at steady flow condition. The operating frequency of pressure cycle was varied between 3 and 60 Hz, which are typical operating frequencies of Gifford-McMahon, pulse tube, and Stilting cryocoolers. First, the measured friction factor for typical wire screen mesh regenerator was nearly same as steady flow friction factor for maximum oscillating Reynolds number up to 100 at less than 9 Hz. For 60 Hz operations, however, the discrepancy between oscillating flow friction factor and steady flow one was noticeable if Reynolds number was higher than 50. Second, the ineffectiveness of regenerator was directly calculated from experimental data when the cold-end was maintained around 100 K and the warm-end around 293 K, which simulates an actual operating condition of cryogenic regenerator. Influence of the operating frequency on ineffectiveness was discussed at low frequency range.