• Journal of Preventive Medicine and Public Health
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• v.36 no.4
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• pp.303-313
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• 2003

General information is summarized, that is necessary to introduce a scientific assessment of the human health and exposure issue concerning dioxin and dioxin-like compound. Scientific literatures were reviewed to assess the background exposures to the dioxin-like compounds for normal residents. Epidemiologic studies were also reviewed to assess malignant and nonmalignant sweets of dioxins. In 1997, the International Agency for Research on Cancer classified 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) as a human carcinogen, primarily based on occupational cohort studies. The US Environmental Protection Agency made the same decision in it's Draft Dioxin Reassessment. Epidemiologic evidences point to a generalized excess of all cancers, without any pronounced excess at specific sites. Reported non-cancer effects included a range of conditions affecting most systems. Among them, chloracne, elevation in gamma glutamyl transferase(GGT), and alterations in reproductive hormones are related to TCDO, Other adverse outcomes, such as lipid concentrations, diabetes, circulatory and heart diseases, immunologic disorders, neurobehavioral effects, and developmental outcomes require further study before their respective relationships to TCDD can be more definitively assessed.

• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.71-78
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• 2011

Cement treating technique, such as deep mixing method, has been used widely to stabilize the dredged clayey soil for many years. Despite of its effectiveness in treating soil by cement, several efforts have also been made to try to reduce the side effect of the cement that used to stabilize the dredged clay. However, authors considered that more detailed study on the physical and mechanical properties of lean-mixed soil-cement has been required to establish the design procedure to apply the practical problems. Therefore, in this study, the curing time and mixing ratio was used as key parameters to estimate the physical and mechanical properties including long-term behavior. The unconfined strength of lean-mixed soil-cement increase continuously during curing period, 270 days, while increasing rate becomes low in ordinary cement-treated dredged clay. We also concluded that cement-treated dredging clay shows apparent quasi overconsolidation behavior even in low cement proportion. By this study, fundamental approach was carried out for effective reuse of very soft dredged clayey soil both in mechanical and environmental aspect. It can be also expected that this study can propose a basic design data to use the lean-mixed soil cement.

• Korean Journal of Mineralogy and Petrology
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• v.33 no.3
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• pp.143-152
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• 2020

Birnessite is a layered manganese oxide mineral with ~7 Å of d-spacing. Because of its high cation exchange capacity, birnessite greatly impacts the chemical compositions of ground water and fluids in sediment pores. Understanding the cation exchange mechanisms requires atomistic investigations of the crystal structures and coordination environments of hydrated cations in the interlayer. In this study, we conducted classical molecular dynamics (MD) simulations, an atomistic simulation method of computational mineralogy, for triclinic Na-birnessite and K-birnessite whose chemical formula are from previous experiments. We report our MD simulation results of the crystal structures, coordination environments of Na⁺ and K⁺, and the polytypes of birnessite and compare them with available experimental results. The simulation results well reproduced experimental lattice parameters and provided atomic level information for the interlayer cation and water molecule sites that are difficult to distinguish in X-ray experiments. We also report that the polytype of the Mn octahedral sheets is identical between Na- and K-birnessite, but the cation positions differ from each other, demonstrating a correlation between the coordination environment of the interlayer cations and the crystal lattice parameters. This study shows that MD simulations are very promising in elucidating ion exchange reactions of birnessite.

• Journal of The Korean Association of Information Education
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• v.20 no.5
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• pp.507-518
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• 2016

In this paper, in order to offer the opportunity to indirectly experience STEAM education and the profession of a quantum computer professional, one of computer experts as a promising occupation of the future, its correlation to the national curriculum was analyzed. STEAM educational program in this paper was developed through which the third or fourth graders in elementary schools can learn about a quantum computer expert and think about it in relevance to their future careers. Yet, it's almost impossible for the students to understand the basic theories of quantum computer based on quantum mechanics, one of most difficult areas of physics. Accordingly, in this proposed textbook, gamification mechanism was applied to arouse students' interest. Moreover, the textbook was developed and applied to the field directly in the way that students would be able to indirectly experience quantum spin, one of most basic principles of quantum computer, quantum cryptography related to quantum computer, incomplete quantum computer and etc. The STEAM educational program for future careers offered in this research is expected to create positive effects for students to explore careers relevant to IT, and to develop related qualities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1B
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• pp.47-55
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• 2011

This study suggests new synthetic unit hydrograph method considering hydrodynamic characteristic on the basin. The suggested method based on width function GIUH, and the procedure is summarized as follows; 1) Draw up a travel distance distribution map (width function) which is raster of length between from center of individual cells to the outlet by GIS. 2) Calculation of travel time distribution map (rescaled width function) by hydrodynamic parameters and travel distance distribution map. 3) Derivation of IUH and Duration UH from rescaled width function. 4) Comparison of shape of UH between suggested method and existing synthetic unit hydrograph methods. The target basins are selected Ipyeong and Tanbu subwatershed in the Bocheong Basin. The target basins are similar scale (watershed area), but different drainage structure (drainage density et al.). Therefore we anticipate that there are different hydrologic response functions because different hydrodynamic characteristics. As a result of derivation of UH, existing synthetic unit hydrograph methods are similar shape of UHs about Ipyeong and Tanbu watersheds, but the suggested method is different shape of ones. As a result of application to observed data, the peak discharge by suggested method is similar to existing synthetic unit hydrograph methods, but the peak time is well correspondence between those. Henceforth, if the suggested method combines with the rational velocity estimation method, it is useful method for synthetic of UH in ungauged watershed.

• The Journal of Engineering Geology
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• v.21 no.2
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• pp.147-156
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• 2011

We conducted laboratory experiments to determine the physical and mechanical properties, and the failure behaviors, of cements for use as grouting material in a $CO_2$-injection borehole. Samples with lour different ratios of water to cement mass (0.4, 1, 2, and 3) were tested. The analyzed properties (porosity, sonic velocity, modulus, and compressive and tensile strengths) varied systematically as a function of the ratio of water to cement (w/c), showing a sharp change between w/c ratios of 0.4 and 1. Triaxial compression tests revealed a clear boundary between brittle and ductile failure depending on the w/c ratio and confining pressure. The present results can be utilized as input parameters for numerical models to understand the initial deformation and failure behavior of grouting cements in a $CO_2$-injection borehole.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3131-3138
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• 2015

At a dermatology during the skin care, photodynamic therapy(PDT) is carried after 5-aminolevulinic acid(ALA), light sensitive material, is applied. At a skin care shop, using drug is prohibited. Thus, the aim of this research was to see the effect of the acne skin by irradiating PDT to the skin without applying ALA. The research method was that 24 female undergraduates who had acne on their face at the level of mild or comedonal, and the participants were divided into four groups(group1: no treatment, group 2: 420 nm of blue visible light, group 3: 660 nm of red visible light and group 4: blue and red visible light). The participants of group 2, 3 and 4 were irradiated with visible light for 20 minutes per week for 6 weeks, and they were compared to group 1. As a result of the research, the number of erythema, sebum, papules and pustules of those who were irradiated with visible light decreased, and the pore size of those also decreased while the amount of moisture increased. If an skin care shop applies PDT to the existing acne skin care, that PDT will influence on the program of a skin care shop is expected.

• Membrane Journal
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• v.33 no.6
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• pp.447-453
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• 2023

The performance of computer systems and the development of various computer simulation programs have made it possible to analyze chemical systems composed of more complex elements, and accordingly, research using molecular dynamics simulation is being actively conducted. Research on calculating the gas permeation characteristics of polymer membranes by molecular dynamics, which was previously conducted mainly through experiments, is receiving attention for gas barrier membranes used in food packaging and pharmaceuticals. Recently, there has been a report that a gas barrier effect appears when a coating film is made using silk fibroin, and in this study, a study was conducted using molecular dynamics simulation to confirm whether an oxygen barrier effect appears when a composite film is made using silk fibroin. We built a single model, calculated the gas permeation characteristics, and compared it with the experimental value to confirm that the model reflects the actual experimental results. Actual composite membrane models were then built and the gas movement path within the polymer was analyzed. As a result, oxygen molecules were found that they could not pass through and was blocked in the fibroin region. Therefore, the composite membrane with silk fibroin has excellent oxygen barrier property and is expected to be useful in food packaging, etc.

• Magazine of the Korea Concrete Institute
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• v.10 no.3
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• pp.175-183
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• 1998

고강도콘크리트의 역학적 특성은 그 압축강도의 증가 이외에도 여러 가지 변화를 갖게 된다. 본 연구에서는 이와 같은 여러 특성의 변화 중 철근과의 부착특성에 관한 해석적 접근을 통하여 고강도콘크리트부재의 부착설계를 위한 이론적인 접근을 시도하였다. 해석의 변수로는 콘크리트의 압축강도, 부착길이 및 피복두께 등 3가지의 변수를 선정하였으며, 해석의 목적은 본 연구에 앞서 실시된 실험의 결과를 예측할 수 있는 단순화된 모델을 개발하고 이를 이용하여 부착실험의 결과를 해석적으로 분석하도록 하였다. 이에 따라 사용된모델은 실험에서 사용한 보단부형 부착시험체의철근과 콘크리트 부착부분의 기하학적 형상을 비교적 실제와 유사하게 모델링시킨 2차원의 평면모델을 사용하였다. 본 연구의 주요결과를 살펴보면 고강도콘크리트의 부착강도는 콘크리트의 피복두께에는 선형으로 비례하게 되나 부착길에는 비례하지 않는 것으로 나타났다. 이와 같은 결고는 기존의 실험결과와도일치하고있으며, 그 원인은 콘크리트의 강성증가에 따라 하중단측에 응력이 집중됨으로써 보통강도콘크리트의 경우와 같이 응력의 균등한 배분을 기대할 수 없기 때문으로 나타났다.

• Defense and Technology
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• no.5 s.291
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• pp.30-41
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• 2003

최근 컴퓨터기술의 발전과 더불어 등장한 컴퓨터모델링기법을 이용하여 현재는 존재하지 않으나 합성에 의해 만들어낼수 있는 새로운 분자들을 예측할 수 있게되었다. 이러한 기술을 에너지물질의 설계에 적용하려는 시도가 1890년대부터 시작되어, 새로운 고밀도 고에너지물질 분자들이 이론적으로 존재 가능하다는 연구결과가 속속 보고되고 있다. 에너지물질 분자들의 주요 구성원소는 C, H, N, O 등인데, 이들 원자들로부터 에너지효율을 극대화하기 위하여 선진국을 위시한 세계 여러 나라의 이론화학자들이 양자역학 이론에 바탕을 둔 ab initio 계산이 주가 되는 분자모델링 기법을 이용하여 새로운 분자들의 존재가능성을 예측하려는 연구가 활발하게 이루어지고 있다. 이러한 새로운 고에너지 물질을 찾으려는 노력의 일환으로 순수한 질소 원자들로만 이루어진 분자들, 일명 질소클러스터(Nitrogen Clusters)에 대한 연구가 진행되고 있는데, N4에서 N60까지 다양한 개수의 질소원자로 이루어진 질소크러스터의 존재가능성이 이론적으로 확인되고 있고, $N5^+$가 최근 합성되는 등 이들 새로운 초 고에너지의 분자들의 출현이 기대된다.