• 한국대기환경학회지
• /
• 제23권3호
• /
• pp.364-372
• /
• 2007

The ozone concentration is one of the important environmental issue for measurement of the atmospheric condition of the country. In this article, two time series ARE models, the direct ARE model and applied ARE model have been considered for analyzing the ozone data at southern part of the Gyeonggi-Do, Pyeongtaek, Osan and Suwon monitoring sites in Korea. The result shows that the direct ARE model is better suited for describing the ozone concentration in all three sites. In both of the ARE models, eight meteorological variables and four pollution variables are used as the explanatory variables. Also the high level of ozone data (over 80 ppb) have been analyzed at the Pyeongtaek, Osan and Suwon monitoring sites.

• 산업기술연구
• /
• 제36권
• /
• pp.23-31
• /
• 2016

This paper presents EMQ models in which some proportion of defective items are produced and some of them are converted to good items through rework process and items not converted are disposed. Numerical models are developed for three cases of disposal and optimal solution of each model is derived. In the first model, if a defective item is found during the production process, only re-workable items are stored and reworked after normal production is finished. Not re-workable items are disposed immediately during normal production. The second model deals with the case where all defective items are stored and items to be disposed are determined in rework process. In the third model, an additional inspection process exists before rework to determine rework or disposal. Numerical examples are presented to validate the proposed models.

• 품질경영학회지
• /
• 제32권3호
• /
• pp.62-67
• /
• 2004

This paper presents and compares two block replacement policies under random use durations. The units are put in service altogether and then idle for some time. The time durations during which units are put in service are random variables. Two block replacement policies, called N-policy and T-policy, are presented. Under N-policy, units are replaced altogether after the Nth use. Under T-policy, units are replaced altogether at the end of the use after cumulative use time T elapses. The failures during use durations are replaced by new ones individually. The cost rate expressions under the policies are derived for exponential use durations. Numerical examples are presented to compare the performances of the two policies.

• 한국농공학회지
• /
• 제29권3호
• /
• pp.145-152
• /
• 1987

This paper suggests a method for the analysis of box girders which are subject to the membrane and the plate bending actions, Moreover, the method is applied to the box girders under distributed loads which have various geometrical types of cross sections and are made out of different materials. The approach is based on the finite element technique in which the structure is considered to be a spatial assemblage of flat plate elements and the deformations of the plates are to be approximated with 9-noded parabolic isoparametric elements. The results are summarized as follows. 1.In all models, the larger the widths of top flange inside of web are, the larger the vertical deflections are. 2.The maximum transverse and longitudinal moments in the composite box girders are judged to be larger than those in the RC box girders. 3.The transverse and the longitudinal moments in top flange of composite box. girders are larger than those in that of the RC box girders. 4.The transverse and longitudinal moments in web and bottom flange of the composite box girders are estimated to be very small in compare to those in web and bottom flange of the RC box girders.

• Journal of Plant Biology
• /
• 제32권3호
• /
• pp.151-162
• /
• 1989

Secretory ducts in the stem of Panax ginseng seedlings are observed with light and electron microscopes to clarify development of the epithelial cells of secretory ducts. Secretory duct initial cell is developed from procambial cell which originated from initial cell is differentiated into ipithelial cell ofsecretory ducts. Intercellular space between the epithelial cells are gradually expanded and differentiated into duct lumen. Disintegrations of epithelial cells occur throughout all the stages of development. The cytoplasm of epithelial cells darken and the epithelial cell wall are lysed, preceding their disintegraton. In the epithelial cell organelles are scattered in the cytoplasm. Development of vcuoles are sparse at the early stage. Starch grains decreased gradually, while lipid droplets increased. Free ribosomes are distributed throughout the cytoplasm and secretory vesicles which originated from rough endoplasmic reticulum and Golgi complex are fused with the plasmalemma. These suggest that the cellular metabolism is active. Microtubules and plasmodesmata are typically observed in the thickened epithelial cell wall. Secretions are accumulated in duct lumen.

• Structural Engineering and Mechanics
• /
• 제7권1호
• /
• pp.53-67
• /
• 1999

The natural frequencies and modes of free vibration of specially orthotropic elliptic and circular plates are analysed using the Rayleigh-Ritz method. The assumed functions used are two-dimensional boundary characteristic orthogonal polynomials which are generated using the Gram-Schmidt orthogonalization procedure. The first five natural frequencies are reported here for various values of aspect ratio of the ellipse. Results are given for various boundary conditions at the edges i.e., the boundary may be any of clamped, simply-supported or fret. Numerical results are presented here for several orthotropic material properties. For rectilinear orthotropic circular plates, a few results are available in the existing literature, which are compared with the present results and are found to be in good agreement.

• 농업과학연구
• /
• 제15권2호
• /
• pp.181-191
• /
• 1988

This paper aims to identify the farmers decision making under uncertainty. Qiuite a few studies have been done on the farmers decision making without uncertainty, but few studies have been made to see farmers decision making under uncertainty in Korea. There are many ways to avoid risks or uncertainty, Wald, Savage, Hurwicz, Laplace, Agrawl-Heady etc. are studied in this field. Fourty farmers were selected as samples. Among those half are the suburbs, and the other half are rural farmers. The results of this study are summarized as follows; First, the suburb farmers are more profit pursuit farmers. Second, not only the rural farmers but the suburb farmers are concerned more safety rather than output maximization. Third, the subsistence farmers and semi-commercial farmers are decided by Wald criterion, but the commercial farmers are decided by Savage or Laplace criterion. Fourth, information is very important in farmers decision making, but the creditability is far from satisfactory to the farmers.

• Journal of the Korean Statistical Society
• /
• 제33권1호
• /
• pp.107-128
• /
• 2004

Bivariate Laplace distributions for which both marginal distributions and Laplace are discussed. Three kinds of bivariate Laplace distributions which are extended bivariate exponential distributions of Gumbel (1960) are introduced in this paper. These symmetrical distributions are compared with asymmetrical distributions of Kotz et al. (2000). Their probability density functions, cumulative distribution functions are derived. Conditional skewnesses and kurtoses are also defined. Their correlation coefficients are calculated and compared with others. We proposed bivariate random vector generating methods whose distributions are bivariate Laplace. With sample means and medians obtained from generated random vectors, variance and covariance matrices of means and medians are calculated and discussed with those of bivariate normal distribution.

• 기술혁신연구
• /
• 제6권2호
• /
• pp.101-121
• /
• 1998

Recent entrepreneurship studies emphasize the importance of entrepreneurial activities of entrepreneurs. This study focuses entrepreneurial behaviors, especially entrepreneurial networking activities of Korean high-tech ventures. Networking activities can utilize external resources which are critical to success, with less resource commitment. This study examines the relationship between characteristics of entrepreneurial networking and performance, and analyses influencing factors of entrepreneurial networking activities. Based on the data from 55 new high-tech ventures in Korea, hypotheses that the characteristics of entrepreneurial networking are related to the performance of new high-tech ventures are tested using regression analysis and t-test. Major findings of this study are as follows: (1) entrepreneurial networking are related to the performance of new high-tech ventures, (2) significant differences are found in the characteristics of entrepreneurial networking between high- and low-performance firms, (3) characteristics of entrepreneurs and firm' technological capabilities are related to the degree of entrepreneurial networking activities. Finally, managerial and policy implications of the study are presented and future research directions are also suggested.

• 한국실내디자인학회논문집
• /
• 제16권6호
• /
• pp.65-76
• /
• 2007

This research is progressed on the premise that there is a basic rule to organize a space in form generation process. In this study first, antecedent researches are inquired, and formal vocabularies related with form generation in space design are founded. Generally in the organizing process of spatial form designer could have selectively combined formal vocabularies consciously or unconsciously, and these formal vocabularies related with form generation are classified with 'formal elements' and 'spatial relationships'. First, as formal elements '2-dimensional line elements(rectilinear, oblique-linear, curvilinear)' are chosen. Second, formal vocabularies of 'spatial relationships' are 37 extracted from literatures related with architectural language or spatial language. Among them there are several vocabularies with similar or same meaning, they are unitized to representative one. Thereupon 20 vocabularies are finally selected as the formal vocabularies of 'spatial relationships', they are addition, subtraction, intersection, superimposition, juxtaposition, shifting, rotation, reflection, scaling, stretching, shear, bending, folding, distortion, articulation, deconstruction, symmetry, repetition, proportion, and asymmetry.