염증성 치은조직에서 부착단백의 발현에 관한 연구

박경근,유형근,신형식 원광대학교 치의학연구소 1996 圓光齒醫學 Vol.6 No.3

The change in vascular adhesion molecule expression and number of infiltrating leukocytes were investigated immunohistochemically in clinically healthy and inflammed gingiva. Monoclonal antibodies to ICAM-1, VCAM-1 and E-cadherin were used to identify positive vessels and leukocyte within gingival biopsies. 10 healthy gingiva and 30 inflammed gingiva was resected by clinical crown lengthening and modified Widman flap operation, respectively. Leukocyte entry into tissues at sites of inflammation is controlled by the interaction between adhesion molecule and endothelium. Because of rapid and severe destructive periodontal disease that is remarkable leukocyte adhesion deficiency, it is very important to understand the mechanism of host defence against periodontal disease. The purpose of this investigation was the characterization of the presence and distri bution of the adhesion molecule( ICAM-1, VCAM-1 and E-cadherin ) in inflammatory gingival tissues compared to clinically healthy gingiva. The results were as followed; 1. ICAM-1 was distributed on basal layer, endothelium and mononuclear cells in healthy gingiva but inflammed gingiva was observed stronger stain than healthy gingiva. 2. Rare expression was observed in both group but few positive VCAM-l cells were investigated in inflammatory gingival tissues 3. E-cadherin was expressed in only epithelium and reduced expression was obse rved in inflammatory gingival tissues. ICAM-1, VCAM-l showed more expression in inflammatory tissues compared to healthy gingiva. Conversely, E-cadherin revealed a opposite result. These finding demonstrate a characteristic distribution and degree of adhesion molecule in healthy and inflammatory gingival tissues. But it is suggested that more detail study be progressive associated with leukocyte adhesion molecule to determine characterization of periodontal disease.

기체냉매의 PVT 거동을 나타내기 위한 상태방정식

박경근,Park, K.,Sonntag, R.E. 대한설비공학회 1995 설비공학 논문집 Vol.7 No.1

The objective of this work is to investigate the form of equations of state for specific refrigerants. In particular, equations of the extended van der Waals form have been studied. As a result, a new equation of state has been developed and tested over ranges of pressure and density up to 5 and 1.5 times critical, respectively. The equation of state separates the compressibility factor into two parts. One is the repulsive compressibility factor and the other is attractive. The former is in the same form of Carnahan-Starling's repulsive term with constant hard-sphere volume. The latter is based on a combination of two different functions linear to density. The equation of state developed here has 12 adjustable parameters and correlates PVT data successfully. All properties are in reduced forms.

냉매의 포화증기밀도 상관식 비교

박경근,강병하,장시열 대한설비공학회 2007 설비공학 논문집 Vol.19 No.6

순수물질 냉매에 대한 새로운 2변수 증기압 상관식의 개발

박경근 대한기계학회 2022 大韓機械學會論文集B Vol.46 No.8

A new two-parameter correlation equation is developed to calculate the refrigerant vapor pressure. Its performance is compared with that of the existing vapor pressure equations using data for 75 pure substances from the NIST Chemistry WebBook. The new equation yields an average absolute deviation of 0.304% that is compared with those of two-parameter Mejbri-Bellagi (0.478%), two-parameter Riedel (0.496%), RPME (0.669%), Antoine (1.43%), and Kirchhoff (2.94%). The new equation also correlates experimental data for 10 environment-friendly HFO/HCFO refrigerants with the average absolute deviation ranging from 0.063% to 0.371% depending on the accuracy of measurement, span of temperature measured, and degree of consistency among different data sets in the literature. 냉매의 포화 증기압을 계산하기 위한 새로운 2변수 상관식을 개발하였다. NIST Chemistry WebBook에서 취득한 75개 물질의 증기압 데이터를 이용하여 기존의 상관식과 성능을 비교하였다. 평균 절대편차를 기준으로, 새로운 상관식(0.304%)은 2변수 Mejbri-Bellagi(0.478%), 2변수 Riedel(0.496%), RPME(0.669%), Antoine(1.43%), Kirchhoff(2.94%) 등의 상관식보다 성능이 우수하다. 또한, 새로운 상관식을 이용하여 10개의 환경친화적 HFO/HCFO 계열 냉매의 실제 증기압 데이터를 곡선적합하였다. 평균절대편차는 0.063%에서 0.371%로 나타났으며, 이 값은 측정 정확도, 측정 온도 범위, 데이터 집합 간의 상호 일관성 정도 등에 의해 결정된다.

A SATURATED LIQUID DENSITY CORRELATION FOR PURE REFRIGERANTS AND OTHER SUBSTANCES

박경근 대한설비공학회 2012 International Journal Of Air-Conditioning and Refr Vol.20 No.2

A modification is proposed of the Chouaieb-Ghazouani-Bellagi (CGB) correlation for the saturated liquid density. After we examined the values of the critical exponent, which is a nonlinear parameter for the CGB correlation, we assumed that the exponent deviates by a small amount from the theoretical value of 0.325. Then, a Taylor-series expansion was conducted for the CGB correlation in order to develop a new correlation with two linear adjustable parameters. Data on the saturated liquid density for 70 pure fluids including 43 refrigerants from the NIST Chemistry WebBook in the whole vapor-liquid saturation range were fitted to the new and existing correlations. The results show that the new correlation yields better performance for substances of which reduced triple point temperature is higher than 0.4. Excellent performance (i.e., AAD < 0.1%) can be achieved with the modified CGB for 14 fluids but only for four fluids with the modified Guggenheim model.

췌장의 낭성종양 2예

박경근,이옥찬,함준수,이민호,이동후,기춘석,박경남 大韓消化器病學會 1994 大韓消化器病學會誌 Vol.26 No.4

순수물질 냉매에 대한 증발 엔탈피 상관식의 성능비교 연구

박경근 대한설비공학회 2003 설비공학 논문집 Vol.15 No.8

A few commonly used correlation equations of the enthalpy of vaporization are reviewed and a new three-parameter correlation equation is proposed. Performance of the proposed equation is examined using the data listed in the ASHRAE table for 22 pure substance refrigerants. The new equation yields an average absolute deviation of 0.14% for 22 refrigerants, which is better than those of other equations, such as Xiang (0.18%), Major-Svoboda-Pick (0.18%), and Somayajulu equation (0.23%).

R-22 대체 상황

박경근 대한설비공학회 2005 설비저널 Vol.34 No.1

Clausius 부등식의 입증과 비교에 관한 연구

박경근,Park, Kyoung-Kuhn 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.2

One Clausius inequality based on an apparatus with a single thermal reservoir is reviewed. Some intricate issues regarding the apparatus are brought up and therefore a preferred way to interpret the Kelvin-Planck statement is suggested. Then it is shown that another Clausius inequality can be established from a direct application of the proposition regarding the efficiency of a Carnot cycle. The establishment is based on an apparatus with two reservoirs, and the resultant inequality involves the temperature of external reservoir. Finally, a different apparatus which also has two thermal reservoirs is utilized to compare the cyclic integral of the former inequality with the one of the latter resulting in the proof of the former inequality which involves the temperature at the system boundary. The applications and limitations of these two Clausius inequalities are discussed.

냉매에 대한 새로운 유형의 포화증기밀도 상관식

박경근 대한설비공학회 1998 설비공학 논문집 Vol.10 No.5

The saturated vapor density correlation proposed here relates logarithmic density to the inverse of temperature. Its performance is examined correlating the date listed in the ASHTAE tables for 40 refrigerants. The correlation equation is valid over the entire range where data point exist and gives better results than a conventional equation with the same number of adjustable coefficients. Number of terms in the equation is a variable so that great flexibility can be given to the representation of data.