API 기준에 근거한 RBI 절차 개발 및 소프트웨어의 구현 (Ⅰ) : 정성적 접근법 Qualitative Approach

심상훈,송정수,김지윤,윤기봉 한국산업안전학회 2002 한국안전학회지 Vol.17 No.3

During the last ten years, effort has been made for reducing maintenance cost for aged equipments and ensuring safety, efficiency and profitability of petrochemical and refinery plants. Hence, it was required to develop advanced methods which meet this need. RBI(Risk Based Inspection) methodology is one of the most promising technology satisfying the requirements in the field of integrity management. In this study, a qualitative assessment algorithm for RBI based on the API 581 code was reconstructed for developing an RBI software. The user-friendly realRBU software is developed with a module for evaluation qualitative risk category using the potential consequence factor and the likelihood factor.

한국 비만 여성의 신체 계측에 의한 체지방 추정

심경원,김지연,서희선,이홍수,이상화,강지현 대한비만학회 2002 The Korean journal of obesity Vol.11 No.2

연구배경 : 국내 비만 여성을 대상으로 비용이 적게 들고 단순하면서도 보다 정확하게 체지방률을 추정할 수 있는 체지방률 추정식을 작성함으로써 쉽게 체지방률과 조절해야하는 지방의 양을 판단할 수 있도록 하고자 한다. 방법 : 이대목동병원 비만클리닉을 처음으로 내원한 19세 이상의 성인 여자 607명 중 체질량지수가 25 kg/㎡ 이상인 500명을 연구대상으로 하여 목, 가슴, 허리, 엉덩이, 대퇴, 하퇴, 발목, 상완, 전완, 손목의 10부위의 둘레와 생체전기저항분석법 (bioelectrical impedance analysis, BIA) 방식의 체성분 분석기를 이용하여 체지방률을 측정하였다. 체지방률 추정식을 구하기 위해 BIA에 의한 체지방률을 종속변수로 하고 , 신체 둘레 계측기 및 신장, 체중, 체질량지수, 연령을 독립변수로 하여 단계별 다중회귀분석 (multiple stepwise regression)을 시행하였다. 결과 : 신장과 체중, 연령, 체질량지수 및 신체 둘레 측정치 중 체지방률을 반영하는 지표는 체질량 지수, 전완둘레, 신장, 엉덩이 둘레, 하퇴둘레였고, 이 다섯가지 지표를 이용한 체지방률 추정식은 66.1%의 예측력과 2.86%의 측정 오차를 나타냈다 (R^2=0.661, SEE=2.86). 결론 : 비만한 성인 여성에서 신장과 체중, 연령 및 신체 둘레 계측치를 이용한 본 연구의 추정식은 체지방률(%)을 적은 오차범위로 비교적 정확하게 반영하였다. Background : This study was conducted to develop a regression equation that accurately estimates body fat percentage using relatively easy and inexpensive method in adult obese Korean women. Method : Data were collected among 500 obese Korean women visiting obesity clinic in Ewha woman's university Mokdong hospital, Seoul, Korea. Height, weight, and circumferences at ten body sites (neck, chest, waist, hip, thigh, calf, ankle, arm, forearm, wrist) were measured s well as total body bioelectrical impedance. Results : The full regression equation estimates body fat percentage included six variables : BMI, forearm circumference, height, hip circumference, thigh circumference. This equation accounted for 66.1% of the variance in body weight measured by bioelectrical impedance, and their standard error of estimate was 2.86%. Conclusion : For the obese Korean women in this study, circumference measurements provided a s relatively good estimation of body fat percentage.

동박적층판 구조에 대한 냉각효율의 예측

이지수,김지민,박주용,이성우,심재우 한국공업화학회 2004 응용화학 Vol.8 No.1

To produce high quality PCB (Printed Circuit Board). CCL (Copper Clad Laminate) that can result in uniform quality is very important. Research and studying the temperature distribution and stress analysis within CCL may not be sufficient. In this study, the temperature distribution of CCL with a separator construction was measured and it was compared with a simulation result. It was found that the separator thickness influenced temperature distribution within CCl. The application of separator was the most effective means of enhancing cooling performance and laminated in a copper-steel-copper separator was effective in uniform cooling.

균일 가열 수직 원형관에서의 일반화된 임계열유속 예측 상관식 개발

이성우,박주용,이지수,심재우 한국공업화학회 2004 응용화학 Vol.8 No.1

A new generalized CHF (Critical Heat Flux) correlation was suggested for water flow in uniformly heated vertical round tubes. The parametric ranges of experimental data were as follows : 0..101≤p (pressure) ≤ 20.679 MPa, 9.92 ≤ G (mass flux) ≤ 18,619.39 lg/㎡s, 0.00102 ≤ D (diameter) ≤ 0.04468 m, 0.03 ≤ L (length) ≤ 4.97 m, -609.33 ≤ Inlet subcooling ≤ 1,655.34 kJ/kg, 0.11 ≤ q_(c) (CHF) ≤ 21.41 MW/㎡, and -0.87 ≤ X_(e) (exit qualities) ≤ 1.58. The new correlation was based on the local condition hypothesis. The new correlation was compared with 4 existing CHF correlation from world literature that claimed to have comparatively good predictions. The results of this study showed that prediction of CHF by the new correlation was in very good agreement with 8,951 experimental CHF data points composed of 12 different sources[1]. The new correlation predicted CHF better than the other ones with average error of -1.34% and root mean square error of 13.44%.

국부가설을 적용한 불균일 가열 수직 원형관에서의 임계열유속 예측

이지수,이성우,김준연,심재우 한국공업화학회 2004 응용화학 Vol.8 No.2

임계열유속 현상이 국부조건변수로 정확히 예측될 수 있다는 가설에 따라 증기 생성률 방정식을 이용해 실제증기건도를 관의 길이에 따라 계산하였으며, 그에 따라 관의 길이에 따른 국부 임계열유속 크기를 계산할 수 있었다. 관에 적용된 열유속분포의 형태와 국부 임계열유속 크기를 감안하여 두 곡선이 전하는 부분을 계산함으로써 임계열유속예측상관식을 개발하였다. 임계열유속 data는 6종, 총 305개를 사용하였으며, 예측 결과는 평균오차 1%, RMS 오차 17%로 분석되었다.

균일 가열 수직 원형관에서의 R-12 임계열유속 예측 상관식 개발을 위한 파라미터의 경향성 분석

이지수,이성우,박주용,김준연,심재우 한국공업화학회 2004 응용화학 Vol.8 No.2

The important parameters that have significant effects on the prediction of CHF (Critical Heat Flux) for R-12 (Dichlorodifluoromethane) were investigated. This was a preliminary study for a R-12 CHF correlation in uniformly heated vertical round tubes. Experimental data of Celata [1], Green and Stevens [2], Groenveld [3], Ilic [4], Katto [5], Merilo and Ahmad [6] and Stevens and Miles [7] were used for this analysis. Four representative CHF data sets at pressure condition of 9, 15, 19, and 27 bar were selected, analyzed, and compared to evaluate the effects other than the system pressure on the CHF were tube diameter (D), mass flux of water (G), and local true mass fraction of vapor (X_(t)). The results of this study have reaffirmed the feasibility that an advanced R-12 CHF correlation for uniformly heated vertical round tubes can be found.

인쇄회로기판 제조 공정에 대한 냉각판 구조의 영향

이지수,김지민,박주용,이성우,심재우 한국공업화학회 2004 응용화학 Vol.8 No.1

Because of strong demand of compacted consumer electronics and rapid improvements in the miniaturization of electronic devices, compact or high density multi-layered PCBs (Printed Circuit Board) production facility with high productivity is being actively sought out. In the cooling process of lamination, it is very important to diminish the temperature deviation within the epoxy resin with respect to the position of press. In this study, we measured the temperature distribution of cooling process for CCL (Copper Clad Laminate) manufacturing. As the result, temperature change in the first plate was bigger than the one in the sixth plate. Much higher efficiency of cooling was observed when copper separator was used compared to the cooling at the natural convection state. In addition, when cooled by the copper plate, the temperature deviation between plates in CCL went up to maximum of 9 degrees.

코크스 오븐에서 에너지 효율 향상을 위한 통합연소진단시스템 개발

이지수,이용국,이성우,심재우 한국공업화학회 2004 응용화학 Vol.8 No.1

In making coke through carbonization process, it is possible to produce the required high quality coke in blast furnace and reduce the cost of energy as well as increase the life of coke oven if we maintain the desired coke oven temperature by means of optimal combustion management (CM). In this study, hybrid combustion diagnostic expert system (HCDES) was developed through analyzing the trend and temperature distribution of flues in the oven and combining the domain expert's knowledge. The model also considered and incorporated the characteristics and the structure of the oven. In developing the diagnostic system, a general and accessible expert language, CLIPS (C Language Integrated Production System) was used.

균일 가열 수직 원형관에서의 전영역 임계열유속 예측 상관식 개발을 위한 파라미터의 경향성 분석

이지수,이성우,김지민,박주용,심재우 한국공업화학회 2002 응용화학 Vol.6 No.2

The important parameters that have significant effects on the prediction of CHF(Critical Heat Flux) were investigated. This was the preliminary study for ageneralized CHF correlation in uniformly heated vertical round tubes. DKU-PDL CHFdatabase[1] was used for this analysis. Four representative CHF data sets at pressureconditions of 1.01, 70, 140, and 200 bar were selected, analyzed and compared toevaluate the effects other than the system pressure on the CHF It has revealed thatthe major variables which inflenced the CHF other than the system pressure (P),were tube diameter (D), mass flux of water (G) and local true mass fraction ofvapor (Xt). The parameters, square root of GXt and square root of D, were alsodetermined to be significant in the parametric trends of the data sets. The results ofthis study have reaffirmed the fesaibility this an advanced generalized CHFcorrelation for uniformly heated vertical round tubes can be found.

실제 증기 건도 예측 모델의 비교

김지민,박주용,이지수,이성우,심재우 한국공업화학회 2003 응용화학 Vol.7 No.1

Three representative models for the reediction of true mass fraction of steam were compared and analyzed to determine most appropriate model that can used to predict the Critical Heat Flux (CHF) for flow of wate in uniformly heated vertical tubes, The models studied were Kroeger & Zuber's [1]. Levy's[2] and Jafri et al.'s[3]. for the comparison. 188 data points from Becker et al.[4] (10 MP a data) were selected as a representative sample from the CHF database that contains a total of 8.912 data points. In case of Kroeger & Zuber vs. Jafri et al., the average error was 0.33% and the root mean square error was 2.47%. In case of Levy vs. Jafri et al., the average and root mean square errors were 1.66%, 2.67% respectively. Jafri et al.'s model can be applied to both uniform and non-uniform heated tubes because it is in a from of rate equation that can easily be used for calculating the true fraction of steam along the length of tube.