• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.1
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• pp.165-172
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• 2002

Generally, the steel rigid frame has been analyzed using finite element analysis tools. While many efforts have been poured into the understanding and accurate prediction for the nonlinear behavior of the columns and beam-columns connections, the base of the columns are modeled as simply hinged or fixed. However, the base of the steel columns practically is neither fixed not hinged. It behaves as semi-rigid. In this paper, the supports of the columns we modeled as semi-rigid and the importance of such approach in moment-resisting columns is evaluated. Two typical buildings designed by the US specification are modeled and analyzed by the finite element based on stiffness method and flexibility method. The column bases of three-story buildings are modeled as rotational springs with a varying degree of stiffness and strength that simulates the semi-rigidity of the base. Depending on the degree of stiffness and strength, the semi-rigidity varies from the hinged to the fixed. Buildings with semi-rigid column bases behaves similarly to the building with fixed bases. It has been numerically observed through the pushover and nonlinear time history analyses that the decrease of the stiffness of the column base induces the rotational demand on the int air beams. an increase of rotation demands on the first store connections and lead to a soft-story mechanists Due often to the construction and environmental effects, undesired reduction of column base stiffness may cause an increase of rotation demands on the first store connections and lead to a soft-story mechanism.

• Geophysics and Geophysical Exploration
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• v.7 no.3
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• pp.207-212
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• 2004

This article reviews recent developments in three-dimensional (3-D) magntotelluric (MT) imaging. The inversion of MT data is fundamentally ill-posed, and therefore the resultant solution is non-unique. A regularizing scheme must be involved to reduce the non-uniqueness while retaining certain a priori information in the solution. The standard approach to nonlinear inversion in geophysis has been the Gauss-Newton method, which solves a sequence of linearized inverse problems. When running to convergence, the algorithm minimizes an objective function over the space of models and in the sense produces an optimal solution of the inverse problem. The general usefulness of iterative, linearized inversion algorithms, however is greatly limited in 3-D MT applications by the requirement of computing the Jacobian(partial derivative, sensitivity) matrix of the forward problem. The difficulty may be relaxed using conjugate gradients(CG) methods. A linear CG technique is used to solve each step of Gauss-Newton iterations incompletely, while the method of nonlinear CG is applied directly to the minimization of the objective function. These CG techniques replace computation of jacobian matrix and solution of a large linear system with computations equivalent to only three forward problems per inversion iteration. Consequently, the algorithms are efficient in computational speed and memory requirement, making 3-D inversion feasible.

• 한국환경농학회:학술대회논문집
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• 2009.07a
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• pp.3-18
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• 2009

It is difficult for consumers to satisfy high safety request with post-management method such as inspection and surveillance, as various changes in-and-out of the country associated with food safety. In terms of food safety problems related to foods, it is crucial to recognize public health and consumer protection and construct pre-preventive Food Control System. A joint committee, FAO/WHO made the following consultations to the National Food Safety System. ${\circ}$ Approach entirely from farm to table ${\circ}$ Get ready for Risk Analysis System ${\circ}$ Secure transparency ${\circ}$ Establish the optimal policy by evaluating the effect of regulation When it comes to summarizing the consultation, it would be accumulated as two key words; "Efficiency" and "Credibility". Whereas the problem of efficiency focuses on precaution rather than post-management, it requires policy option to maximize consumer's benefit by evaluating the cost for the Food Safety Management and its benefit. Also, analyzing risk's character and amount, demanding an optimal means, and introducing scientific analysis system put much value on the stakeholder's communications are procedure's security which can satisfy both "Efficiency" and "Credibility" simultaneously. Especially, it is emphasized here that Risk Assessment need to be separated from Risk Management. This action is a valid means of credibility security throughout improving transparency. A number of nations and organizations have reformed the method of food management passing through reflection and examination of the prior National Food Safety Management since BSE occurred in Britain, 1996. FSA; Food Standard Agency, AFFSA, EFSA, BfR, and FSC are Risk Assessment Organization functionally separated from Risk Management Organization, JECFA, JMCFA, JMPR, JEMRA in Codex charge Risk Assessment internationally. In case of advanced countries excluding several those such as The U.S. and so forth, though these Risk Assessment Organizations are either separated functionally within Risk Management Organization or operated as apart organ, common factors are in which it has independence as Science Base. While securing independence of Risk Assessment Function, it is a tendency Risk Management should be functionally unified into efficiency as well. Though Germany constructs integral Risk Management System of diverse ways according to social and political conditions of each country such as GFOCP, DVFA, SNFA, CFIS and AQIS, there is a key word in the center, "Securing efficiency of Food Safety Management". However our nation has a representative plural；diversified system with The U.S., we took a step forward for unification as empowering policy's generalization；adjustment and Risk Assessment Function by means of enacting the "Food Safety Fundamental Law" in 2008 and establishing the "Food Safety Policy Commission" with private and governmental sectors in the Prime Minister's office. Even though the unification of Risk Management hereby increased, there is the lack of strengthening function of Risk Assessment and securing independence. It needs to be required for the professional committee in Food Safety Policy Commission to develop as a exclusive office of Risk Assessment by separating from a policy decision. Administrative Branches should reinforce feeble functions such as fundamental investigation；research for carrying out Risk Assessment with securing efficiency throughout reassessment of prior Risk Management Means.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.19 no.4
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• pp.381-389
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• 2009

Confined spaces are inherently dangerous workplace and many fatal and nonfatal accidents have been reported. Even though these accidents occur in various kinds of confined spaces, there has rarely been reported on the health hazard agent, i.e., the types of gases and their concentration ranges. Therefore in this study, we evaluated several toxic and asphyxiating gas concentrations in various confined spaces. We surveyed 57 manholes, 3 sewage treatment plants, 2 yellow radish manufacturing companies and 7 barges to measure the concentrations of oxygen($O_2$), hydrogen sulfide($H_2S$), carbon monoxide(CO), ammonia($NH_3$). Lower Explosion Limits(LEL) and Volatile Organic Compounds (VOCs). Those four types of confined spaces occupies 56% of accidents during last 9 years in Korea. In 57 manholes, the concentration varied according to the types of manholes; rainfall and sewage, and by location; residential and industrial areas. Sewage manhole in industrial area was evaluated as the most hazardous than other types of manhole like rainfall manholes, residential sewage manholes. The highest $H_2S$ concentration and the lowest $O_2$ concentration at sewage manhole in industrial area were 300 ppm, 8.7% respectively. In 3 sewage treatment plants, $H_2S$ and $NH_3$ concentrations were reached up to the 500 ppm and 200 ppm respectively. Two yellow radish manufacturing companies showed the concentrations of 316 ppm, 505.2 ppm, 90 ppm and 15.7% for $H_2S$, CO, VOCs and $O_2$, respectively. Seven barges showed 15.9%~20.9% oxygen concentration. Gas species and concentration ranges varied by the types and location of confined spaces; CO, $H_2S$, $O_2$ could be hazardous in manhole, especially manhole connected to sewage plants. CO, $H_2S$, LEL, $O_2$, $NH_3$ should be controlled in sludge silo and sluge pumping confined spaces in sewage treatment plant. The activity of lifting out radish from the storage tank was evaluated more hazardous rather than the other activities in yellow radish manufacturing industry. The employers must conduct the survey to identify all possible confined spaces in their local workplace prior to performing the tasks. At the national level to reduce the accidents in the confined spaces, we suggest that systemic approach and active education program including possible hazards, standard operation procedures, ventilation plan, and personal protective equipment in confined spaces should be implemented.

• Journal of the Korean Association of Geographic Information Studies
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• v.5 no.4
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• pp.106-118
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• 2002

In recent years, synthetic and systematic management with conservation-oriented strategy for Baekdu-daegan, which is the greatest chine as well as the major ecological axis of the Korean Peninsula, is being required to cope adequately with the various kinds of developmental urge. For this, spatially definite zoning for the managerial area on Baekdu-daegan has to be completed first. This study is to take into consideration the traditional concepts of stream and watershed as well as the actual disturbance on Daegan area, and to propose the process for reasonably establishing the managerial boundary adjacent to the Ridges. The case site with topographically diverse characteristics was selected, and the analyses on watershed, road network and land use were carried out using the digital maps and Landsat TM images. Based on these analyses results, the managerial boundaries as alternatives from the Ridges were produced by watershed expansion process, and used for tracing the changes of road occupancy rate and the areal ratio of various land use types to the relevant watersheds to search out the adequate managerial boundary. The results show that watershed expansion process could be effective tool for establishing the managerial boundary, and the fourth expanded watershed would be included for the adequate managerial boundary of the case site.

• Journal of Forest and Environmental Science
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• v.11 no.1
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• pp.81-101
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• 1995

Random amplified polymorphic DNA (RAPD) technology, a recent approach in molecular genetics, is much usable to select the elite trees and to maximize the genetic gain in forest tree breeding program, providing a clue to determine the genetic marker-trait correlation. This review intorduces research on bark thickness and breeding strategy in Pinus elliottii, Pinus caribaea and their hybrid by Queensland Forest Service and ForBio Research Pty Ltd, University of Queensland, which employ RAPD technology. Genetic linkage map of $F_1$ hybrids includes 186 RAPD markers and 16 linkage groups (1641 cM long in total) and 6 quantitative trait loci are located putatively for bark thickness. Following recent research results and experiences in pine breeding programs, the forseeable stages in the application and development are proposed for marker assisted selectin; stage 1-determination of species specific markers for genes controlling traits of commercial interest, and stage 2-determination of marker-allele association for specific allelic variants within pure species. As pines inherit their megagametophytes from the seed parent and zygotic embryos from both male and female parents, the determination of marker-trait correlation is possible even in embryo stage, eventually making ways for the early selection of elite individuals.

• Journal of Environmental Policy
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• v.7 no.3
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• pp.41-61
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• 2008

Although the size of the organic food market in Korea has increased significantly, its further development is hampered by the information asymmetry between the producers and consumers of organic food. It isn't just about revitalizing the market; it's also about Korean farmers surviving an era of trade liberalization. In order to produce more value-added products, the information asymmetry issue has to be resolved regarding the organic food market and other agricultural credence goods such as Han-woo(Korean beef). Therefore, measuring information asymmetry has become a central issue. One way to measure asymmetry is to use Game Theory. However, in practice, estimating payoffs at the industry level is hard to accomplish, and even when it is possible, the reliability of the estimated payoffs is not guaranteed. As an alternative, the concept of Information Entropy(disorder level of information), developed by Shannon(1948), was used in this study. It is proposed that this measure should be used when assessing the level of information asymmetry in the Korean organic food market. Using recent data, it was found that information entropy in the Korean organic food market has been decreasing constantly since 2003. Therefore, it was proposed that measures should be adopted by the government to improve the certification system of organic food.

• Journal of the Korean Geotechnical Society
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• v.28 no.10
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• pp.5-16
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• 2012

Geotechnical buried structures with relatively light weight have been suffering from uplift damage due to liquefaction in the past earthquakes. The factor of safety approach by Koseki et al. (1997a), which is widely used in seismic design, predicts the triggering of uplift. However, a method for "quantitative" estimates of the uplift displacement has yet to be established. Estimation of the uplift displacement may be an important factor to be considered for designing underground structures under the framework of performance-based design (ISO23469, 2005). Therefore, evaluation of the uplift displacement of buried structure in liquefied ground during earthquakes is needed for a performance-based design as a practical application. In order to predict the uplift displacement quantitatively, a simplified method is derived based on the equilibrium of vertical forces acting on buried structures in backfill during earthquakes (Tobita et al., 2012). The method is verified through comparisons with results of centrifuge model tests and damaged sewerage systems after the 2004 Niigata-ken Chuetsu, Japan, earthquake. The proposed flow diagram for performance-based design includes estimation of the uplift displacement as well as liquefaction limit of backfill.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.1
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• pp.109-117
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• 2015

Background: Follow-up clinical consultations could improve overall health status as well provide knowledge and education for cancer prevention. Materials and Methods: This is the cross-sectional study using the Korean Community Health Survey (KCHS) 6th edition for 2012, with 115,083 respondents who underwent cancer checkups selected as subjects. Associations between the presence of consultation and the socioeconomic status were determined using statistical methods with the SAS 9.3 statistical package (Cary, NC, USA). Findings: Among the recipients, 32,179 (28.0%) received clinical consultations after cancer screenings. Those in rural areas (odds ratio, OR=0.71, 95% confidence interval (CI), 0.69-0.73) visited follow-up clinics less frequently than did those in urban areas. Starting at the elementary school level, as the education level increased to middle school (OR=1.26, 95% CI: 1.19-1.34), high school (OR=1.29, 95% CI: 1.23-1.36) or college (OR=1.76, 95% CI: 1.65-1.89), the participation rates also increased. When compared with the lowest quartile group, the quartile income level showed a statistical trend and difference as follows: second lowest quartile (OR=1.11, 95% CI: 1.07-1.16), third lowest (OR=1.12, 95% CI: 1.07-1.17) and highest quartile income (OR=1.29, 95% CI: 1.23-1.35). In addition, the people with economic activities (OR=0.87, 95% CI: 0.84-0.90) visited follow-up clinics less frequently than did the others. Current smokers (OR=0.93, 95% CI: 0.89-0.98) and inveterate drinkers (OR=0.88, 95% CI: 0.85-0.94) had a tendency to visit less often than did non-smokers and other drinkers with all cancers combined. Interpretation: We suggest primary prevention through lifestyle modifications including smoking and drinking, and environmental interventions may offer the most cost-effective approach to reduce the cancer burden.

• Journal of Bio-Environment Control
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• v.22 no.2
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• pp.123-130
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• 2013

$CO_2$ enrichment systems have been recently used to shorten the growth period of plants and the improvement of harvest and its quality. To accomplish these goals, manifold should be designed to supply the same amount of $CO_2$. In this study, CFD approach has been used to understand the effects of geometric parameters, such as tube and hole diameters. An optimized geometry has been derived through pipe and tube part, respectively. As a result, the deviation of flow rate less than 0.1 g/s was expected at all holes of the $CO_2$ enrichment system.