• Korean System Dynamics Review
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• v.4 no.2
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• pp.153-171
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• 2003

In this study, we tried to build a model which can deal with the efficient and effective operation of electric power industry, especially focused on the nuclear industry. Here, SD(system Dynamics) approach is used to visualize the underlying phenomenon of the nuclear power industry. SD is a methodology for studying and managing complex feedback systems, such as one finds in business and other social systems, The span of SD applications has grown extensively and now encompasses work in corporate planning and policy design, public management and policy, biological and medical modeling, energy and the environment. Recently, according to the report from KEPCO(Korea Electric Power Corporation), they are considering delaying a new power plant construction. It may be based upon business fluctuation downsized from Korean economic crisis in 1997 and freezing of construction funds due to unstable foreign exchange rate. At this point, we need desperately a kind of strategic model that would contribute to cope with the current business situation, energy generation, Production, and resulting Pollution. Specifically, this model, using SD approach, starts with the detailed drawing of influence diagram, which describes those relevant key points on nuclear power generation systems in electric power industry of Korea. These include such (actors as the operation of nuclear industry and parameters related to the decision making for business policy. Based upon the above-mentioned influence diagram drawn, we developed SD simulation model to evaluate and analyze strategic management of KBPCO. Based on our analysis, we could demonstrate how simulation model can be applied to the real electric power generation in Korea.

• Journal of the Korean Operations Research and Management Science Society
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• v.26 no.2
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• pp.99-109
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• 2001

In this study, we tried to build a model which can deal with the efficient and effective operation of electric power industry, especially focused on the nuclear industry. Here, SD (System Dynamics) approach is used to visualize the underlying phenomenon of the nuclear power industry. SD is a methodology for studying and managing complex feedback systems, such as one finds in business and other social systems. The spend of SD applications has grown extensively and now encompasses work in corporate planning and policy design, public management and policy, biological and medical modeling, energy and the environment. Recently, according to the report from KEPCO (Korea Electric Power Corporation), they are considering delaying a new power plant construction. It may be based upon business fluctuation downsized from Korean economic crisis in 1997 and freezing of construction funds due to unstable foreign exchange rate. At this point, we need disparately a kind of strategic model that would contribute to cope with the current business situation, energy generation, production, and resulting pollution. Specifically, this model, using SD approach, starts with the detailed drawing of influence diagram, which describes those relevant key points on nuclear power generation systems in electric power industry of Korea. These include such factors as the operation of nuclear industry and parameters related to the decision making for business policy. Based upon the above-mentioned influence diagram drawn, we developed SD simulation model to evaluate and analyze strategic management of KEPCO. Based on our analysis, we could demonstrate how simulation model can be applied to the real electric power generation in Korea.

• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.813-825
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• 2019

This paper investigated the effects of a government production and shipment stabilization policy and the improvement plan for vegetables in Korea. In this study, a simulation focused on the changes in farm income for Chinese cabbages & radishes using scenarios. The result shows an increase in farm income according to the government policy. In the short-term, demand and supply are fixed, and the policy effect is positive due to the price support effect of the project. However, for mid- to long-term, the price decreases due to the expansion of supply by business beneficiaries, which is likely to be adversely affected by an unstable supply and demand. This increases the burden of government and local government subsidies. This phenomenon is expected to be amplified as the ratio of production and shipbuilding stabilization programs and items expand. When expanding items and adjusting and setting the percentage of participation in the project, it is desirable to set and operate the appropriate business ratio taking into consideration the demand. To improve the effectiveness of the policy, the following remedies were suggested. First, national supply and demand guidelines should be set up, and the autonomous supply and demand control of the producers should be guided by the different preservation according to the implementation of the supply and demand control obligation. As for detailed equipment, it is necessary to establish the reproduction price for each item, set the base price for each wholesale market, increase the incentive for the producers to participate, and fund a business budget to secure business stability.

• Computational Structural Engineering
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• v.8 no.2
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• pp.153-161
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• 1995

The dynamic instability for snapping phenomena has been studied by many researchers. There is few paper which deal with the dynamic buckling under the load with periodic characteristics, and the behavior under periodic excitation is expected the different behavior against step excitation. In this study, the dynamic direct snapping of shallow elliptic paraboloidal shells is investigated under not only step excitation but also sinusoidal and seismic excitations, applied in the up-and-down direction. The dynamic nonlinear responses are obtained by the numerical integration of the geometrically nonlinear equations of motion, and examined by the Fourier spectral analysis in order to get the frequency-dependent characteristics of the dynamic instability for various load levels. The results show that the dynamic instability phenomenon carried out from stable to unstable region reveals considerably different mechanism depending on the characteristics of excitations.

• Geomechanics and Engineering
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• v.12 no.3
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• pp.523-539
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• 2017

Clay soils are typical for their swelling properties upon absorption of water during rains and development of cracks during summer time owing to the profile desorption of water through the inter-connected soil pores by water vapour diffusion leading to evaporation. This type of unstable soil phenomenon by and large poses a serious threat to the strength and stability of structures when rest on such type of soils. Even as lime and cement are extensively used for stabilization of clay soils it has become imperative to find relatively cheaper alternative materials to bring out the desired properties within the clay soil domain. In the present era of catastrophic environmental degradation as a side effect to modernized manufacturing processes, industrialization and urbanization the creative idea would be treating the waste products in a beneficial way for reuse and recycling. Bottom ash and ecosand are construed as a waste product from cement industry. An optimal combination of bottom ash-eco sand can be thought of as a viable alternative to stabilize the clay soils by means of an effective dispersion dynamics associated with the inter connected network of pore spaces. A CATIA model was created and imported to ANSYS Fluent to study the dispersion dynamics. Ion migration from the bottom ash-ecosand pile was facilitated through natural formation of cracks in clay soil subjected to atmospheric conditions. Treated samples collected at different curing days from inner and outer zones at different depths were tested for, plasticity index, Unconfined Compressive Strength (UCS), free swell index, water content, Cation Exchange Capacity (CEC), pH and ion concentration to show the effectiveness of the method in improving the clay soil.

• Journal of Korean Association for Spatial Structures
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• v.12 no.4
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• pp.109-118
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• 2012

The large-space single-layer lattice dome is relatively simpler in terms of the arrangement of the various framework members and of the design of the junction than the multi-layered lattice dome, can reduce the numbers and quantity of the framework members, and has the merit of exposing the beauty of the framework as it stands. The single-layer lattice dome, however, requires a stability investigation of the whole structure itself, along with an analysis of the stress of the framework members, because an unstable phenomenon called "buckling" occurs when its weight reaches critical levels. Many researchers have systematically conducted researches on the stability evaluation of the single-layer lattice dome. No construction case of a single-layer lattice dome with a 300-m-long span, however, has yet been reported anywhere in the world. The large-space dome structure is difficult to erect due to the gigantic span and higher ceiling compared with other common buildings, and its construction cost is generally huge. The method of erecting a structure causes major differences in the construction cost and period. Therefore, many researchers have been conducting various researches on the method of erecting such structure. The step-up method developed by these authors can reduce the construction cost and period to a great extent compared with the other general methods, but the application of this method inevitably requires the development of system supports in the center section as well as pre-existing supports in the boundary sections. In this research, the safety during the construction of a single-layer lattice dome with 300-m-long span using pre-existing materials was examined in the aspect of structural strength, and the basic data required for manufacturing the supports in the application of the step-up method developed by these authors during the erection of the roof structure were obtained.

• Applied Biological Chemistry
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• v.26 no.1
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• pp.28-34
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• 1983

The change of lactate dehydrogenase(LDH) activity and the possibility of the existence of LDH. isozyme were examined with different parts of soybean sprout. The enzyme activity was little changed in cotyledons throughout the early stagy of germination. However, hypocotyls and roots showed the continuous decline of the enzyme activity since the radicle emerged from seeds. It was found that LDH from hypocotyls. and roots was unstable as compared with LDH from cotyledons, even at low temperature. The enzyme from hypocotyls and roots was not purified with a good yield when the purification procedure developed for LDH from cotyledons. was employed. LDH from hypocotyls and roots has the Rm value of 0.29, and 0.25 from cotyledons. The apparent Km value for LDH from cotyledons was 0.45mM with sodium pyruvate, while crude homogenate of hypocotyls or roots showed biphasic phenomenon with two Km values 0.014 and 0.45mM. The results indicate the possibility that crude homogenate of hypocotyls or roots may contain a different LDH isozyme from the LDH of soybean reported previously.

• Korean Journal of Food Science and Technology
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• v.54 no.3
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• pp.272-279
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• 2022

Polyphenols are chemically unstable, and their bioactivities are reduced through oxidation. Photosensitizers (PS) induce photo-oxidation in various food systems. In this study, effects of dietary PS such as riboflavin (Rb), erythrosin B (EB), and zinc protoporphyrin on the auto-oxidation of polyphenols, gallic acid (GA) and tannic acid (TA) were evaluated under a fluorescent light. The formation of oxidation products from GA and TA increased in a PS concentration- and irradiation time-dependent manner. In addition, Rb and EB induced significant reduction in the polyphenols contents and ABTS radical scavenging activity of GA and TA under light. PS significantly enhanced the amount of reactive oxygen species generated from GA and TA. Therefore, the interaction of polyphenols with PS under light results in acceleration of polyphenol oxidation. This phenomenon should be carefully considered during food processing and storage.

• The Journal of the Korea Contents Association
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• v.21 no.11
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• pp.657-679
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• 2021

This study aimed to explore the experience and nature of emotional care for elderly parent living alone for middle-aged adult who formed initial insecure attachment with his or her parent. To this end, 12 middle-aged people aged 45 to 60 (3 males and 9 females) were recruited as subjects of the study, interviewed in-depth, and analyzed using Colaizzi's phenomenological research method. As a result of the study, 60 constitutive meanings, 18 themes, and 4 thematic groups were derived for the experience of middle-aged adult who experienced insecure attachment to his or her parent and caring for the emotional needs of elderly parent living alone. Thematic groups included "negative experiences that caused emotional exhaustion," "emotional driving force in emotional care," "the role of helper in parental care," and "economic and physical content in emotional care". This study is meaningful in that it revealed the phenomenon of experiences of emotional care for parent living alone by middle-aged adult who had an initial unstable attachment with his or her parent to understand them and contributed to the provision of counseling data.

• Journal of English Language & Literature
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• v.53 no.2
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• pp.307-333
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• 2007

When W. E. B. Du Bois says that "the problem of the twentieth century is the problem of the color line," such a statement clearly recognizes the significance of the issue of racial identity, a cultural phenomenon called 'passing.' Both Johnson in The Autobiography of an Ex-Colored Man and Larsen in Passing confront this issue. Both novels, using the metaphor of passing, not only trace the racial anxiety and race politics of the time but also expose the unstable landscape of the established social and cultural boundaries of racial identity. Mapping out multiple meanings and various dimensions of passing, this paper argues how Johnson's and Larsen's narratives display the ambivalence of color line while they at the same time complicate, problematize, and destabilize the mainstream racial boundaries and differences. It furthers to delineate how the two writers, with difference, deal with the problem of passing, the significance of racial identity, and black middle class values along with its intraracial differences. Rather than draw a clear definition of and a definitive closure on passing narrative, this paper focuses on its complexities and undecidability, challenging every dimension of its established significations. It also explores the complex dynamic between passing act and individual identity, for passing here is not just a racially signified term but extends its significance to the other factors of identity, such as class and even sexuality. Johnson and Larsen open up a site for a newly emergent, modern racial identity for black middle class in the twentieth century American urban spaces. Both writers, illuminating the subversive and slippery nature of language in their passing narrative, clearly herald new, different forms of Afro-American writings and themes for the different century they face.