• Journal of the Korean Crystal Growth and Crystal Technology
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• v.7 no.1
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• pp.143-150
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• 1997

The electrical properties of polysilicon thin films implanted with $B_2H_6$ diluted in $H_2$ as dopant source using ion mass doping technique and the effect of radiation damage on the dopant activation behavior were investigated. Comparing the SIMS profiles of boron in polysilicon films with that obtained from computer simulation using TRIM92 the most probable ion species were $B_2H_x\;^+$(x＝1, 2, 3‥‥) type molecular ions. As a result of the Implantation of energetic massive ions, a continuous amorphized layer was created in polysilicon films where the fraction of amorphized layer varied with doping time. This amorphization comes from the fact that mass separation of implanting species is not employed in this ion mass doping technique. In the dopant activation behavior, reverse annealing phenomenon appeared in the intermediate annealing temperature range for a severely damaged specimen. The experimental result showed that the off-state current of the p-channel polysilicon thin film transistor is dependent on the degree of radiation damage.

• Korean Journal of Agricultural and Forest Meteorology
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• v.3 no.3
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• pp.143-149
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• 2001

This study was conducted to analyze the propertis, acidity and chemical compositions of the snowfall in the bare land and Idlest stand. The research sites of this study are the Daegwalyung (a high hill) and Woongyori in Pyungchang-gun, Kangwon province. The results of this study are as follows: The snowfall pH showed large changes when the snowfall was small. The more snow falls, the smaller changes of the pH are narrow. According to the local conditions, it means that the acid deposition changed over adsorption ratio in suspended matters of the atmosphere. Changes of the ion concentrations for the snowfall in the forest stand showed a thendency to increase. Chemical composition of the snowfall for each sampling site showed that the ion concentrations of $Ca^{2+}$and anions had higher value than other ions.s.

• Progress in Superconductivity and Cryogenics
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• v.24 no.4
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• pp.1-5
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• 2022

We investigate the effect of surface disorder on the lower critical field (H_c1) of MgB₂ thin films with a thickness of 850 nm, where the disorder on the surface region is produced by the irradiation of 140 keV Co ions with the dose of 1 × 10¹⁴ ions/cm². The thickness of the damaged region by the irradiation is around 143 nm, corresponding to ~17% of the whole thickness of the film, thereby forming the disordered MgB₂ overlayer on the pure MgB₂ layer. The magnetic field dependence of magnetization, M(H), for the pristine MgB₂ thin film and the film with overlayer is measured at various temperatures, and H_c1 is determined from the difference (△M) between the Meissner line and magnetization signal with the criterion of △M = 10^-3 emu. Intriguingly, the film with the disordered overlayer shows a remarkably large H_c1(0) = 108 Oe compared to the H_c1(0) = 84 Oe of pristine film, indicating that the disordered MgB₂ overlayer on the pure MgB₂ layer serves to prevent the penetration of vortices into the sample. These results provide new ideas for improving the superheating field to design high-performance superconducting radio-frequency cavities.

• Reproductive and Developmental Biology
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• v.34 no.3
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• pp.143-151
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• 2010

Pluripotency of human embryonic stem cell (hESC) is one of the most valuable ability of hESCs for applying cell therapy field, but also showing side effect, for example teratoma formation. When transplant multipotent stem cell, such as mesnchymal stem cell (MSC) which retains similar differentiation ability, they do not form teratoma in vivo, but there exist limitation of cellular source supply. Accordingly, differentiation of hESC into MSC will be promising cellular source with strong points of both hESC and MSC line. In this study, we described the derivation of MSC like cell population from feeder free cultured hESC (hESC-MSC) using direct differentiation system. Cells population, hESC-MSC and bone marrow derived MSC (BM-MSC) retained similar characteristics in vitro, such as morphology, MSC specific marker expression and differentiation capacity. At the point of differentiation of both cell populations, differentiation rate was slower in hESC-MSC than BM-MSC. As these reason, to verify differentially expressed molecular condition of both cell population which bring out different differentiation rate, we compare the molecular condition of hESC-MSC and BM-MSC using 2-D proteomic analysis tool. In the proteomic analysis, we identified 49 differentially expressed proteins in hESC-MSC and BM-MSC, and they involved in different biological process such as positive regulation of molecular function, biological process, cellular metabolic process, nitrogen compound metabolic process, macromolecule metabolic process, metabolic process, molecular function, and positive regulation of molecular function and regulation of ubiquitin protein ligase activity during mitotic cell cycle, cellular response to stress, and RNA localization. As the related function of differentially expressed proteins, we sought to these proteins were key regulators which contribute to their differentiation rate, developmental process and cell proliferation. Our results suggest that the expressions of these proteins between the hESC-MSC and BM-MSC, could give to us further evidence for hESC differentiation into the mesenchymal stem cell is associated with a differentiation factor. As the initial step to understand fundamental difference of hESC-MSC and BM-MSC, we sought to investigate different protein expression profile. And the grafting of hESC differentiation into MSC and their comparative proteomic analysis will be positively contribute to cell therapy without cellular source limitation, also with exact background of their molecular condition.

• Journal of Microbiology and Biotechnology
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• v.3 no.2
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• pp.99-107
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• 1993

Two strains (No. 26 and 143) of bacteria which secrete both pectinase and raw-starch-digesting amylase simultaneously, were isolated from various domestic soil samples. The two bacteria were identified as Pasteurella ureae judging by their morphological and physiological characteristics. The optimal culture conditions for the production of raw-starch-digesting enzyme by the Pasteurella ureae 26 were using $NH_4NO_3$ as the nitrogen source at $37^{\circ}C$ with the pH of 7.5, and 15 of C/N ratio. Since the enzyme was produced only when raw or soluble starch was used as a carbon source, but not when glucose or other sugars was used, the enzyme was considered to be an inducible enzyme by starch. Thin layer chromatography of the hydrolyzed product of starch by the raw-starch-digesting enzyme of the strain No. 26 showed that glucose, maltose and other oligosaccharides were present in the hydrolyzates, and therefore the enzyme seemed to be ${\alpha}-amylase$. The enzyme had adsorbability onto raw com starch in the pH range of 3 to 9.

• Membrane and Water Treatment
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• v.9 no.6
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• pp.385-392
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• 2018

Poly vinyl chloride (PVC) was chemically modified, and used for ultrafiltration to analyze the performance. Non-solvent induced phase separation (NIPS) method was used to prepare membranes. The neat PVC membrane was casted and used as a control membrane. Modified membrane was prepared by reacting PVC with ethanolamine (EA) in the casting solution (labeled as CM-PVC). Pure water permeability (PWP) was evaluated by measuring pure water flux. Humic acid was used as model foulant solute to analyze flux and rejection ability of membranes. Flux and rejection data of neat and modified membranes were compared to prove the improvement in the filtration performance. The experimental results showed that for PVC and CM-PVC, PWP was calculated to be ~64 and ${\sim}143L/m^2{\cdot}h$, respectively, and the rejection of humic acid was found to be 98% and 100%, respectively. TGA was carried out to analyze the effect of chemical modification on the thermal stability of polymer. FT-IR analysis was another characterization technique used for the comparative study.

• Transactions of Materials Processing
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• v.18 no.2
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• pp.135-143
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• 2009

In the casting industry field, a lot of researches have been carried out to maximize soundness and productivity and improve quality of mass produced products. The researches on the optimum mould design by using computer simulation have achieved a lot of accomplishments in the die-casting process especially. Their results are utilized to mass-produce sound products in their field. But there are some difficulties to use the simulation in order to make the design of product and mould. In general, repetitive calculations of computer simulation require much analyzing time in order to make sound design of them. Another difficulty is that only expertise technicians can analyze results of the simulation. In order to solve such a problem, we are building mould design optimization system which consists of knowledge-based module, simulation, optimization module and interactive modeler(it is based on the commercial modeler). By using and interacting between these modules of that system, we can easily make an optimum design of mould and construct the database. This study introduce the general process of the system and connection method between the modules is mentioned above and some examples to apply it to real product.

• 한국생물공학회:학술대회논문집
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• 2005.04a
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• pp.140-143
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• 2005

This study was concerned with the optimization of liquid culture conditions for mycelial growth and polysaccharide production and its physicochemical properties in Cordyceps militaris. The one factor at a time method was adopted to investigate the effects of medium composition, environmental factors and C/N ratio. Among the these varialbles, glucose 80g/L, yeast extract 10g/L, $MgSO_4{\cdot}7H_{2}O\;0.5g/L$, $KH_{2}PO_4\;0.5g/L$ were proved to be the most suitable carbon, nitrogen, and mineral sources, respectively. The optimal temperature, initial pH, working volume were identified to be $24^{\circ}C$, 7.0 and 100ml, respectively. Under the optimal conditions, the strategies in shake flask culture and 5L jar fermentor led to mycelial growth of 29.43 g/L, 28.88g/L and polysaccharide production of 2.53g/L, 6.38 g/L, respectively. Among the phisicochemical properties, relative concentrations(w/v) of total sugar, uronic acid, protein and hexoseamine were identified to be 74.07%, 1.13%, 0.91%, and 0.46%, respectively. The fraction of neutral and acidic polysaccharide were identified to be 81.9% and 18.1%, respectively.

• Journal of Biosystems Engineering
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• v.15 no.2
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• pp.143-150
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• 1990

This study was conducted to estimate the ratio of Repair & Maintenance (R&M) costs to purchasing price that is one of the important factors for calculating the management costs of farm machinery. For this purpose, hour of use and R & M costs of power tiller and its attachments utilized results that were investigated with 400 sample units, 50 units by years of use from 1 to 8 years in 1988. The results obtained are summarized as follows; 1. The ratio of R & M costs per hours and annual R & M costs, accumulated R & M costs when sercice life of power tiller is 7 years were 0.017%, 5.50% and 38.52%, respectively. And in case of rotary, these ratio when its service life is 6 years were 0.072%, 7.16% and 43.0%, respectively. 2. The relationship between accumulated hours of use(t) and accumulated R & M costs(Y) of power tiller and its attachments were $Y=19.3t^{1.3}$ in power tiller, $Y=0.03t^{2.09}$ in plow, $Y=48.84t^{1.25}$ in rotary and $Y=7.45t^{1.15}$ in trailer. 3. The ratio of accumulated R & M costs to purchasing price when service life of power tiller is 7 years was 38.5%, and in case of rotary, this ratio when its service life is 6 years was 43.0%.

• Journal of the Korean Society for Heat Treatment
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• v.21 no.3
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• pp.137-143
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• 2008

Effect of quenching medium on the mechanical properties of ductil iron GCD 50 has been investigated using ADI treated specimens. The specimens have been austenitized at $900^{\circ}C$ for 2 hours, followed by controlled cooling to $800^{\circ}C$ under the cooling rate of $0.05^{\circ}C/sec$, then austempered at $380^{\circ}C$, $330^{\circ}C$, $280^{\circ}C$ and $230^{\circ}C$ for 1 hour. The specimens treated in the salt of 5% water were found to have higher tensile strength than that of the normal salt bath. Elongation and impact energy increased in proportion to the increase of retained austenite volume fraction. The increase of cooling rate of the salt by the addition of 5% water to the salt resulted in the increase of retained austenite volume fraction and the formation of fine bainitic ferrite.