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최순용,이낙영 충남대학교 기초과학연구소 2000 忠南科學硏究誌 Vol.27 No.2
In this paper, we studied the performance of a production control plan which forms a keynote of every promising business area. The production control plan along with diversitifying its business items is a main concern of each company myth an active business. We investigated classifying characteristics, processes, product types, and computation of the necessary product time per each unit process, which altogether comprise the whole work processes of the products of the Korea Minting and Security Printing Co.(KOMSEP). The most suitable manufacturing structure for stable and systematic production and inventory management has been sought by setting the most at able total stock level for bank bills(l0.000 won. 5.000 won, and 1,000 won bills) and checks. This requires calculation of the product lead time per each unit process from order to delivery, which matches the whole work processes required for production in KOMSEP.
Nak-Soon Choi,Ming-Tao Kang,Hak-Kyeong Kim,Sang-Yong Park,Sang-Bong Kim 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.2
This paper presents a sliding mode controller based on Ackermann's fomula and applies it to stabilizing a two-wheeled mobile inverted pendulum in equilibrium. The mobile inverted pendulum is a system with an inverted pendulum on a mobile cart. The dynamic modeling of the mobile inverted pendulum was established under the assumptions of a cart with no slψ and a pendulum with only planar motion. The proposed sliding mode controller was based upon a class of nonlinear systems whose nonlinear part of the modeling can be linearly parameterized. The sliding surface was obtained in an explicit form using Ackermann's fomula, and then control law was designed from reachability conditions and made the sliding surface attractive to the equilibrium state of the mobile inverted pendulum. The proposed controller was implemented in a Microchip PIC16F877 micro-controller. The developed overall control system is described. The simulation and experimental results are presented to show the effectiveness of the modeling and controller.
Soon-Sun Bak,Chang-Suk Kong,Sook-Hee Rhee,Chi-Woong Rho,Nak-Ku Kim,Keyng-Lag Choi,Kun-Young Park 한국식품영양과학회 2006 Preventive Nutrition and Food Science Vol.11 No.3
Young radishes (YR, yeolmu in Korean) were cultivated in soil with and without sulfur. Control YR-kimchi and sulfur YR-kimchi were prepared using the young radishes cultivated in the soil without and with 1,818 g/㎥ sulfur, respectively. Fermentation of the YR-kimchis were conducted at 5℃ for 6 weeks. The control and sulfur YR-kimchis were reached pH 4.39 and pH 4.31 with 0.98% and 1.04% acidity at 5 weeks, respectively. At a higher concentration of 20 μL/assay, the sulfur YR-kimchi juice exhibited higher inhibitory effects (84%) on the growth of HT-29 human colon cancer cells than the control YR-kimchi (57%). Methanol extract from the YR-kimchis also led to similar results to those of the juices. In the inhibition study by hematocytometer, YR-kimchis inhibited the growth of cells in a time-dependent manner. Sulfur YR-kimchi induced apoptosis as determined by 4,6-diamidino-2-phenylindole (DAPI) staining and decreased Bcl-2 expression of active anticancer compounds, when compared to the control YR-kimchi. These results suggested that preparing kimchi using YR cultivated in the presence of sulfur, which can help to synthesize active compounds, could increase the anti-cancer activity of sulfur YR-kimchi.
Geochemical Characteristics of Granite From KURT for Sorption and Diffusion Experiments
Nak Kyu Kim,Chung-Kyun Park,Jae-Kwang Lee,Seonggyu Choi,Jang-Soon Kwon 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.1
The deep geological repository consisting of a multi-barrier system (engineered and natural barriers) is generally designed to isolate the high-level radioactive waste. The natural barrier is outermost portion to secure safety of the disposal. Crystalline rocks are considered for potential geological repository media to retard and inhibit the migration of radionuclides when the radionuclides leak from the canister and break through the engineered barrier. Sorption and diffusion processes play a major role in retardation of the radionuclides in deep underground environment. In order to evaluate the migration of radionuclides in the safety assessment or geochemical modelling, distribution coefficient and diffusivity of radionuclides are required as input data. In this study, we performed mineralogical and geochemical analysis for a crystalline rock (e.g., granite) to use the sorption and diffusion experiment. The fresh rock samples are obtained from a deep core samples (DB-2) drilled up to 1 km from the surface at KURT (KAERI Underground Research Tunnel) site. For the optical and microscopic examination, thin sections of the rock sample were provided. The rock samples were crushed into powder size to analyze major and trace elements of the whole-rock aliquots. The powdered specimens also used for mineral identification and measurement of specific surface area. The major constituent minerals of the granite are plagioclase, quartz, and K-feldspar and the minor minerals are phlogopite, biotite, and chlorite. According to the results of geochemical analysis, the granite specimens generally contain more than 70wt% of SiO2 and 8wt% of total alkali oxides (Na2O + K2O). The trace elements normalized to primitive mantle compositions show positive Cs, Rb, U, K, and Pb anomalies and negative Nb and Ti anomalies. The rock samples have an average density of 2.62 g·cm?3 and an average porosity of 0.222%. The crushed samples represent the specific surface area of 0.2087 m2·g?1 for the 75–150 μm fraction and 0.1616 m2·g?1 for the 150–300 μm fraction by BET method, respectively. The granite specimens will be used for the sorption and diffusion experiments to evaluate the radionuclides’ geochemical behaviors. The mineralogical and geochemical properties provided in this study can be useful in understanding the sorption and diffusion processes of significant radionuclides under the geological disposal environments.
Choi, Nak Heon,Kwon, Soon-kwan,Kim, Hansung The Electrochemical Society 2013 Journal of the Electrochemical Society Vol.160 No.6
<P>In this study, the oxidation of the V(II) by dissolved oxygen was examined quantitatively using UV-visible spectrophotometry. UV-visible spectrophotometry is an accurate method of determining the concentration of vanadium ions at both the negative and positive half-cell electrolytes. To apply Beer's law, the concentration should be diluted below 0.15 M to achieve a linear relationship between the absorbance and concentration. UV-visible spectrophotometry revealed that the concentration of V(II) in the negative half-cell electrolyte decreases continuously with cycling due to the rapid oxidation of the V(II) by dissolved oxygen. This decrease gives rise to an imbalance between the positive and negative half-cell electrolytes, which results in a significant capacity loss.</P>
Nak Kyu Kim,Chung-Kyun Park,Jae-Kwang Lee,Seonggyu Choi,Jang-Soon Kwon 한국방사성폐기물학회 2022 한국방사성폐기물학회 학술논문요약집 Vol.20 No.2
The deep geological disposal system is aimed to permanently isolate the high-level radioactive waste from the biosphere through a multi-barrier system composed of engineered and natural barriers. The buffer material used for the engineered barrier should have the performance to prevent and retard the migration of radionuclides to the outside of the deep disposal facility when radionuclides are released from a disposal canister by infiltration of groundwater after a long period of time. When the hydraulic conductivity of compacted bentonite is sufficiently low, the migration of radionuclides released into the surrounding rock can be significantly reduced since they are sorbed to bentonite during the diffusion process. Therefore, an investigation on diffusion of radionuclides in compacted bentonite is a fundamental task to obtain essential data for the safety assessment of the deep geological disposal system. The migration of radionuclides by diffusion can be evaluated by diffusion coefficient. In order to obtain the apparent diffusion coefficients of Sr, Sm, and Eu in compacted Ca-bentonite (1.6 g/cm3) a through-diffusion experiment have been carrying out. A cylindrical apparatus consists of a source cell with an appropriate concentration of radionuclides and diffusion cell filled with radionuclide free solution where the concentration is gradually increased by diffusion of radionuclides. The compacted bentonite was installed between the both cells. The sample used for the experiment is a Ca-type bentonite named Bentonil-WRK, and the diffusion experiment was performed under an oxidizing condition using a synthetic groundwater simulating KURT groundwater composition. The diffusion experiment will be terminated when an increasing rate of concentration of nuclides in the diffusion cell becomes constant over time. The concentration change with regard to the geochemical characteristic of the nuclide may appear to be apparently slow.In this study, the experimental results of the through-diffusion test of Sr, Sm, and Eu in the initial stage (~4 months) were presented. Through the results of the initial stage, the period of the through-diffusion experiment can be rearranged and also it is expected that the initial results provide the qualitative and quantitative diffusion properties of each nuclide.