• 대한기계학회논문집B
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• 제24권3호
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• pp.363-372
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• 2000

An experiment was carried out to evaluate the heat transfer enhancement and the pressure drop characteristics for liquid nitrogen using wire-coil-insert technique under horizontal two-phase conditions. The tube inner diameters were 8 mm and 15 mm, respectively and the tube length was 4.7 m. The helix angle of the wire coil insert was $50^{\circ}$ and its length was 4.7 m. Heat transfer coefficients for both the plain and the enhanced test tubes were calculated from the measurements of temperatures, flow rates and pressure drops. A correlation in a power-law relationship of the Nusselt number, Reynolds number and Prandtl number for the heat transfer was proposed which can be available for design of cryogenic heat exchangers. The correlation showed that heat transfer coefficients for the wire-coil inserts were much higher than those for plain tubes, increased by more than $1.8{\sim}2.0$ times depending upon the range of the equivalent Reynolds number. The correlation was compared with other various correlations in the turbulent flow conditions.

• 한국통신학회논문지
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• 제27권7A호
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• pp.695-704
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• 2002

멀티미디어에 삽입된 워터마크의 검출은 저작권 보호 및 인증 분야에서 매우 중요한 역할을 한다. 최근 워터마크의 검출에 많이 사용되는 유사도 기반 알고리즘은 대상 영상의 분포 특성을 이용하지 않기 때문에 검출 성능이 떨어지는 단점을 가진다. 따라서 본 논문에서는 웨이블릿 변환 영역에서 상승적 방법에 의하여 삽입된 워터마크에 대한 효율적인 검출 알고리즘을 제안하였다. 제안한 워터마크 검출 알고리즘은 통계적 판단 이론에 따라 Bayes 판단 이론, 웨이블릿 계수들의 확률 분포 모델, 및 Neyman-Pearson 정의에 기반을 둔다. 따라서 제안한 검출 알고리즘에서는 주어진 오류 검출 확률에 대하여 간과 검출 확률을 최소화할 수 있는 장점이 있다. 제안한 검출 알고리즘의 성능 평가는 견고성 측면에서 수행되었고, 실험 결과로부터 제안한 알고리즘이 유사도 기반 알고리즘에 비하여 우수한 성능을 나타냄을 확인하였다.

• 한국안광학회지
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• 제4권1호
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• pp.7-14
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• 1999

본 논문에서는 한국인 17세에서 30세사이의 38명을 대상으로 Vision Tester로 자각적 굴절이상을 측정하고, 난시가 있는 사람은 등가구면도수틀 취했다. 각막 굴절력과 곡율반경은 Baush & Lomb사 Keratometer로 측정했으며 전방의 깊이, 수정체의 두께, 초자체의 깊이, 안축의 길이 등은 A-mode Ultrasonography로 측정 했고, 각막 두께는 Phakometry로 측정했다. 굴절이상과 안광학요소의 상관계수를 구한 결과 안축의 길이, 초자체의 깊이, AL/CR 비와는 각각 0.95, 0.96, 0.95로 아주 높은 상관관계가 있었고, 각막곡율반경, 굴절력, 수정체의 두께와는 각각 0.60, 0.66, 0.67로 나타났으며, 각막의 두께와는 괄목할 만한 상관관계가 없었다.

• Journal of Preventive Medicine and Public Health
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• 제56권4호
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• pp.377-383
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• 2023

Objectives: Korea and Japan have managed the spread of coronavirus disease 2019 (COVID-19) using markedly different policies, referred to as the "3T" and "3C" strategies, respectively. This study examined these differences to assess the roles of active testing and contact tracing as non-pharmaceutical interventions (NPIs). We compared the proportion of unlinked cases (UCs) and test positivity rate (TPR) as indicators of tracing and testing capacities. Methods: We outlined the evolution of NPI policies and investigated temporal trends in their correlations with UCs, confirmed cases, and TPR prior to the Omicron peak. Spearman correlation coefficients were reported between the proportion of UCs, confirmed cases, and TPR. The Fisher r-to-z transformation was employed to examine the significance of differences between correlation coefficients. Results: The proportion of UCs was significantly correlated with confirmed cases (r=0.995, p<0.001) and TPR (r=0.659, p<0.001) in Korea and with confirmed cases (r=0.437, p<0.001) and TPR (r=0.429, p<0.001) in Japan. The Fisher r-to-z test revealed significant differences in correlation coefficients between the proportion of UCs and confirmed cases (z=16.07, p<0.001) and between the proportion of UCs and TPR (z=2.12, p=0.034) in Korea and Japan. Conclusions: Higher UCs were associated with increases in confirmed cases and TPR, indicating the importance of combining testing and contact tracing in controlling COVID-19. The implementation of stricter policies led to stronger correlations between these indicators. The proportion of UCs and TPR effectively indicated the effectiveness of NPIs. If the proportion of UCs shows an upward trend, more testing and contact tracing may be required.

• 한국축산식품학회지
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• 제43권4호
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• pp.553-562
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• 2023

With an increase in meat consumption, the need to measure the weight of each primal cut of pork has increased. Recently, automation devices have been used to measure the weight of each primal cut of pork. The objective of this study was to investigate the accuracy of VCS2000, one of the non-invasive pig carcass analyzers. Production levels of 7 primal cuts of 50 pigs were measured with VCS2000. Average error rates between dissected value for each primal cut and VCS2000 measurement values of ham, shoulder picnic, belly, loin, and shoulder blade were around 5%. Average error rates for spare rib and tenderloin were about 10%. Correlation coefficients between the dissected value and the VCS2000 measured value for ham, shoulder picnic, loin, belly, and shoulder blade were high at 0.66-0.83. Correlation coefficients of spare rib and tenderloin were low at 0.35 and 0.47. Coefficient of determination of the VCS2000 measured value for each primal cut by regression analysis was 0.77 or more for ham, shoulder picnic, loin, and shoulder blade and 0.63 for belly. Coefficients of determination for spare rib and tenderloin were low at 0.40 and 0.27. In addition, the coefficient of determination of VCS2000 for each primal cut was higher than that of the dissected value for all primal cuts. In conclusion, pig carcass analysis using the VCS2000 has a high reliability for pork cuts with high production levels, but a relatively low reliability for pork cuts with low production levels and high fat levels.

• 한국환경보건학회지
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• 제25권3호
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• pp.51-57
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• 1999

This study was carried out to investigate the concentrations of Ni, Cr and Cu, to analyze the correlations among those, and between concentrations and traffic volumes by type of car in roadside ambient air at Chongro-, Chungkechon- and Kangnam terminal- area in Seoul from October 1st to October 31st in 1997. The results were as follows ; 1. The means of concentrations of Ni in roadside ambient air were 34.1, 25.1 and 23.6 ng/m$^3$ at Chungkechon, Kangnam terminal and Chongro area, respectively. The highest concentrations of Ni by time were 26.8 in the evening, 45.5 in the evening and 49.4 ng/m$^3$ in the forenoon at Chongro, Chungkechon and Kangnam terminal area, respectively. 2. The means of concentrations of Cr in road side ambient air were 97.7, 80.1 and 70.9 ng/m$^3$ at Chong, Chungkechon and Kangnam terminal area, respectively. The highest concentrations of Cu by time were 205.3 in the evening, 114.4 in the evening and 92.3 ng/m$^3$ in the forenoon at Chongro, Chungkechon and Kangnam terminal area, respectively. 4. The tendencies of concentrations of Ni and Cr by time were similar to each other. Especially, at Kangnam terminal area, correlation coefficients between concentrations of Ni and Cr and the traffic volume of bus were high(r=0.997,0.975). 5. The tendency of concentration of Cu and the traffic volume of passenger car at each area were high(r=0.832, 0.968) 6. Correlation coefficients between Cu and Zn, and between Ni and Cr were 0.762 and 0.842, respectively. This means that the possibility of co-existence of Cu-Zn or Ni-Cr is very high.

• 한국작물학회지
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• 제45권4호
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• pp.245-250
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• 2000

This study was conducted to analyze the responses of some agronomic traits to the different cultural environments and relations among the agronomic traits for selecting sesame varieties with higher cultural stabilities. The indexes for stability parameters measured were coefficient of variability, heritabilities, genetic correlations and path coefficients of agronomic traits according to locations and years in Korea. The heritabilities of agronomic traits showed different by locations and years. Number of seeds per capsule and 1000 seeds weight showed higher heritabilities, but stem length and seed weight per plant showed relatively lower heritabilities. Average heritabilities of some agronomic traits in 1998 were comparatively higher than those of 1999. Of six areas, Jinju area showed biggest coefficient of yield variability in 1998-1999. Iksan and Taegu areas showed higher heritabilities in 1998, but Iksan and Jinju areas showed lower heritabilities in 1999. Genetic correlations were slightly higher than corresponding phenotypic correlations. Stem length showed positive genetic correlation with the number of capsules per plant, and seed weight per plant and the number of capsule per plant showed positive genetic correlation with seed weight per plant. On the analysis of path coefficients, stem length and number of capsules effected highly on grain yield. Great regional variations were observed on the effects of agronomic traits on grain yield. Higher direct effects of stem length on grain yield were observed at Suwon, Chungwon, Taegu, Jinju and Naju areas, but in Iksan area was observed higher direct effect of the number of capsules per plant on grain yield in 1998. In 1999, higher direct effect of stem length on grain yield was observed at Chungwon and Suwon areas. Iksan and Taegu areas were also observed higher direct effect of the number of capsule per plant on grain yield.

• 한국미생물·생명공학회지
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• 제27권1호
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• pp.54-61
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• 1999

Measurement of inhibition of bioluminescence in Photobacterium phosphoreum has been porposed as a sensitive and rapid procedure to monitor toxic substances. However, at first, $EC_{50}$ which shows degree of toxicity to each toxic substances must be calculated. QSAR (Quantitative Structure Activity Relationship) model can be used to estimate $EC_{50}$ to save time and endeavor. Moderately high correlation coefficients ($r^2{\geq}$ 0.97) were calculated from the linear correlation between $EC_{50}$ and molecular connectivity indices of CAHs (chlorinated aliphatic hydrocarbons)such as $^0X$, $^0X^V$, $^1X$, $^2X$ and $^3X^v_c$ and quadratic correlation between $EC_{50}$ and $^0X$, $^0X^V$, $^2X^V$, $^3X_c$, $^3X^V_c$ and P. It shows that the molecular connection indices in carbon structure is contributed to biological characters with linear relation and that in the other one with quadratic relation. The $EC_{50}$ of chlorophenol derivatives had quadratic relation with the value of octanol/water prtition coefficients ($r^2$=0.99) and linear and quadratic relation with the number of chlorine compound (($r^2{\geq}$0.94). This confirms the already known trend of increasing toxicity with increasing ability of a compound to diffuse through cell membrane and number of chlorine substitution.

• Journal of the Korean Data and Information Science Society
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• 제23권3호
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• pp.457-465
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• 2012

본 연구의 목적은 한국대학교육협의회 대학정보공시센터의 '대학알리미'에서 주요 대학지표들을 분석하고, 지표들 간의 연관성과 통계적 모형을 추정하는데 있다. 먼저 상관계수에 대한 통계적 검정을 이용하여 변수들 간의 통계적으로 유의한 상관성을 추정하고, 이들 주요 지표들의 모형을 추정하기 위해서 회귀분석 방법의 변수선택 방법을 이용하여 회귀 방정식을 추정하여 변수들 간의 연관성을 조사하였다. 변수선택의 판정기준에 따른 방법으로 전진선택법과 후진제거법, 단계별 회귀방법을 사용하였다.

• 한국환경과학회지
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• 제23권3호
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• pp.399-407
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• 2014

In this study, before and after sunset carbon dioxide concentration and air temperature were observed in two points of atmosphere (lower observation point of the GL + 0.1 m, the upper observation point of GL + 1.0 m) on the foreshore at located in Suncheon Bay and their variations were analyzed. Observation was performed on the foreshore on 2~4 August 2010. Instrument (VAISALA, GMP343) was set two hours before sunset and then observation was made continuously for six hours. In three days, observed carbon dioxide concentration was 375~419 ppm, and the air temperature was in the range of $28.7{\sim}32.5^{\circ}C$. The average concentration of carbon dioxide was 388~399 ppm in the upper observation point and 386~396 ppm in the lower observation point. It was higher in the upper observation point and its fluctuations were similar in two observation points. Correlation coefficients between carbon dioxide concentration and air temperature in the upper observation point were in the range of -0.64~-0.88, and were calculated -0.65 to -0.90 in the lower observation point. For the carbon dioxide concentration, correlation coefficients between the upper part and the lower part were very high as 0.98 in three times. For the air temperature, correlation coefficients between the upper part and the lower part were very high as 0.97 and 0.99. In the same observation time, the slope of the linear regression function as carbon dioxide concentration in the lower observation point for the upper observation point was in the range of 0.97~1.01. Carbon dioxide concentration was slightly higher in the upper observation point. Because carbon dioxide in the lower observation point was closer on the surface of the foreshore and absorbed from atmosphere to the foreshore. In this study, it was showed that the vertical variation of carbon dioxide concentration was insignificant in the several meter scale of atmosphere on the surface of the foreshore.