• 응용통계연구
• /
• 제21권4호
• /
• pp.615-620
• /
• 2008

공업실험에서는 주효과의 검정력을 높일 목적으로 교호작용효과에 대한 예비검정의 결과가 유의하지 않은 경우에, 이 효과를 오차항으로 풀링한 후에 주효과의 유의성을 검정하는 때때로 풀링 (Sometimes pooling)의 분석 방법을 사용한다. 이 소고에서는 때때로 풀링의 규칙에 관한 참고문헌의 내용을 정리하고, 블록효과가 오차항으로 풀링되었다는 사실이 알려 졌을 때에 독립표본에 의한 모평균의 차이에 대한 95% 신뢰구간의 길이가 쌍체비교에 의한 신뢰구간의 길이보다 짧을 확률을 다양한 예비검정의 유의수준 ${\alpha}_1$값과 충분한 검정력이 보장되지 않은 블록의 크기인 $2{\leq}n{\leq}13$ 범위에서 살펴보았는데, 그 결과는 풀링한 경우에 주효과에 대한 검정력이 높아진다는 사실을 뒷받침하고 있다.

• International Journal of Air-Conditioning and Refrigeration
• /
• 제12권1호
• /
• pp.37-49
• /
• 2004

Four different data reduction methods for the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two heat and mass transfer models and two fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the reduced heat transfer coefficients revealed that the single potential heat and mass transfer model yielded the humidity-independent heat transfer coefficients. Two fin efficiency models-enthalpy model and humidity model-yielded approximately the same fin efficiencies, and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

• 한국대기환경학회지
• /
• 제15권2호
• /
• pp.121-138
• /
• 1999

This study was carried out to evaluate the performance of a sampling and analytical methodology for the measurement of selected volatile organic compounds (VOCs) in the ambient air. VOCs were determined by the adsorbent tube sampling and automatic thermal desorption coupled with GC/FID and GC/MSD analysis. Target analytes were aromatic VOCs, including BTEX, 1,3,5-and 1,2,4,-trimethylbenzenes(TMBs), and naphthalene. The methodology was investigatedwith a wide range of performance criteria such as repeatability, linearity, lower detection limits, collection efficiency, thermal conditioning, breakthrough volume and calibration methods using internal and external standards. standards. Stability of samples collected on adsorbent tubes during storage was also investigated. In addition, the sampling and analytical method developed during this study was applied to real samples duplicately collected in various indoor and outdoor environments. Precisions for the duplicate samples and distributed volume samples appeared to be well comparable with the performance criteria recommended by USEPA TO-17. The audit accuracy was estimated by inter-lab comparison of both duplicate samples and standard materials between the two independent labs. The overall precision and accuracy of the method were estimated to be within 30% for major aromatic VOCs such as BTEX. This study demonstrated that the adsorbent sampling and thermal desorption method can be reliably applied for the measurement of BTEX in ppb levels frequently occurred in common indoor and ambient environments.

• 한국정보과학회논문지:데이타베이스
• /
• 제34권1호
• /
• pp.46-58
• /
• 2007

마이크로어레이 데이타는 동시에 수 만개 유전자의 발현 값을 포함하고 있기 때문에 질병의 발현 형질 분류에 매우 유용하게 쓰인다. 그러나 동일한 생물학적 주제라 할지라도 여러 독립된 연구 집단에서 생성된 마이크로어레이의 분석결과는 서로 다르게 나타날 수 있다. 이에 대한 주된 이유는 하나의 마이크로어레이 실험에 참여한 샘플의 수가 제한적이기 때문이다. 따라서 개별적으로 수행된 마이크로어레이 데이타를 통합하여 샘플의 수를 늘리는 것은, 보다 정확한 분석을 하는데 있어 매우 중요하다. 본 연구에서는 이에 대한 해결 방안으로 두 단계 접근방법을 제안한다. 제 1 단계에서는 개별적으로 생성된 동일주제의 마이크로어레이 데이타를 통합한 후 인포머티브(Informative) 유전자를 추출하고 제 2 단계에서는 인포머티브 유전자만을 이용하여 클래스 분류(Classification) 과정 후 분류자를 추출한다. 이 분류자를 다른 테스트 샘플 데이타에 적용한 실험결과를 보면 마이크로어레이 데이타를 통합하여 샘플의 수를 증가시킬수록, 비교 방법에 비해 정확도가 최대 24.19% 높은 분류자를 만들어 내는 것을 알 수 있다.

• 설비공학논문집
• /
• 제15권1호
• /
• pp.73-85
• /
• 2003

Four different methods of reducing the heat transfer coefficients from experimental data under dehumidifying conditions are compared. The four methods consist of two different heat and mass transfer models and two different fin efficiency models. Data are obtained from two heat exchanger samples having plain fins or wave fins. Comparison of the data with the reduction methods revealed that the single potential heat and mass transfer model yielded the humidity independent heat transfer coefficients. Two different fin efficiency models - enthalpy model and humidity model - yielded approximately the same fin efficiencies and accordingly approximately the same heat transfer coefficients. The heat transfer coefficients under wet conditions were approximately the same as those of the dry conditions for the plain fin configuration. For the wave fin configuration, however, wet surface heat transfer coefficients were approximately 12% higher. The pressure drops of the wet surface were 10% to 45% larger than those of the dry surface.

• 한국농공학회지
• /
• 제39권1호
• /
• pp.93-101
• /
• 1997

This paper presents yield surfaces and hardening laws for describing the state of an unsaturated soil under isotropic compression and suction changes. The yield surface is formulated within the framework of hardening plasticity using two independent sets of stress variables : the excess of total stress over air pressure and the suction. And the application of the yield surfaces and hardening laws are confirmed from the result of the experiment. To this end a series of suction-controlled isotropic tests are conducted on clayey soils. Matric suction is controlled by the axis translation technique using high air entry ceramic disk. The specimens are compacted using a half of Proctor compaction energy with 5 % lower of water content than the optimum moisture contents. From test results, existence of the yield surfaces and an application of hardening laws to samples are confirmed by comparison between test and predicted results. And it is confirmed that LC yield locus is extened with the total plastic deformations induced by suction or stress changes, however, SI yield locus is only extended with the plastic deformations by induced suction changes.

• The Journal of Asian Finance, Economics and Business
• /
• 제6권4호
• /
• pp.65-74
• /
• 2019

This study has two main purposes; first, it examines the effect of capital structure on profitability of Islamic and conventional banks; second, it determines that whether the capital structure of Islamic and conventional banks is same or not. A sample of ten banks was taken over the period 2006-2016. Independent samples T-test was used for finding the comparison between the capital structure of Islamic and conventional banks while for assessing the impact of capital structure on profitability, regression analysis (Fixed effects model) was used. Results showed that the capital structure of both types of banks was similar except for bank size which differed significantly. Moreover, ROA was negatively correlated to the capital structure of both conventional and Islamic banks. In contrast, ROE was positively correlated to the capital structure of both conventional and Islamic banks. In addition to that, two explanatory variables were positively correlated while two were negatively correlated to EPS for both Islamic and conventional banks. This study proves the existence of prominent theories of capital structure (pecking order theory and trade-off theory) for both conventional and Islamic banks in Pakistan and also validates the economies of scale.

• 대한치과기공학회지
• /
• 제36권1호
• /
• pp.17-23
• /
• 2014

Purpose: The purpose of this study was to analyze and compare the relative accuracy of digitized stone models of lower full arch, using two different scanning system. Methods: Replica stone models(N=20) were produced from lower arch acrylic model. Twenty digital models were made with the white light and blue LED($Medit^{(R)}$, Korea) scanner. Two-dimensional distance between the landmarks were measured on the Delcam $CopyCAD^{(R)}$(Delcam plc, UK). Independent samples t-test was applied for comparison of the groups. All statistical analyses were performed using the SPSS software package(Statistical Package for Social Sciences for Windows, version 12.0). Results: The absolute disagreement between measurements made directly on the two different scanner-based dental digital models was 0.02~0.04mm, and was not statistically significant(P>0.05). Conclusion: The precision of the blue LED optical scanner was comparable with the digitization device, and relative accuracy was similar. However, there still is room for improvement and further standardization of dental CAD technologies.

• 한국의류산업학회지
• /
• 제14권3호
• /
• pp.448-453
• /
• 2012

This study aims to categorize age groups for shoes manufacturing including shoes size and boot tree development for Koreans. In order to carry out the research, the characteristics of different parts of foot in relation to size are analyzed according to age and sex, making use of human body measurement database. As a result of statistical analysis, it was found that the measurement items such as foot length, metatarsal tibiale, foot breadth and instep circumference of a person reached the range of standard deviation and average numerical figures of an adult group (18-24) from the age of 14 in men's case, and from 12 for women's case, which indicates the time of completion of their foot growth. Based on these findings where males of 14 years old and females of 12 are within similar measurement range to adults, it is necessary to categorize the age groups for shoe sizing system into the following four groups: males 13 years old or under, males 14 years old or over, females 11 years or under, and females 12 years or over. The proportional measurement produced by dividing each measurement item of foot parts by foot length was compared in an independent samples t-test, and there were meaningful differences according to different foot shapes of the two age groups of males 13 or under - males 14 or over, and females 11 or under - females 12 or over. Also, the independent samples t-test for the age groups of males 13 or under - females 11 or under, and males 14 or over - female 12 or over, showed similar meaningful differences, which indicates the differences in foot shapes of male and female during the period of growth.

• 한국의류학회지
• /
• 제34권6호
• /
• pp.902-912
• /
• 2010

This study compares and contrasts the consumer decision-making styles (CDMS) of South Korean and American Generation Y females. A total of 117 American female and 206 Korean female consumers completed self-report survey questionnaires to assess their consumer decision making styles. Exploratory principal components factor analysis using varimax rotation was used to categorize the items into an underlying set of American and Korean decision-making characteristics. Two-tailed independent t-tests were conducted to examine the differences between the two groups when items appeared to have common factors. Factor analysis identified five common factors between the two samples (i.e., enjoyment, shopping aversion, price consciousness, brand consciousness, and quality consciousness). The t-test results report significant differences in the items reported in each factor between American and Korean females. Some of the factors are more indicative of American female Generation Y consumers than Korean female Generation Y consumers. For example, the American female sample seemed to enjoy shopping and prefer brand names more than the female Korean sample. Koreans females seem to have a higher aversion to shopping than Americans; in addition, Koreans females seem to be more accepting of discount and outlet stores, will wait until the price is low before buying a product, and prefer sales when shopping. Based on the findings, the instrument identified varying CDMS between the two samples used. Previous studies using the Sproles and Kendall (1986) instrument experienced the same issue (Bakewell & Mitchell, 2004, 2006; Bauer et al., 2006; Durvasula et al., 1996; Fan & Xiao, 1998; Hanzaee & Aghasibeig, 2008; Mitchell & Walsh, 2004; Siu et al., 2001; Walsh et al., 2001). The results support the idea that no single instrument can be used to examine CDMS in different cultures. This suggests that each country has a CDMS with internal characteristics. Limitations and research for future studies are also discusse.