• Journal of IKEEE
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• v.16 no.2
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• pp.109-115
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• 2012

We propose a control system consisted of TRIAC PWM module and sequential start control system attenuating voltage-dip and inrush current caused by starting of inductive load network. To minimize the high voltage-dip and inrush current induced from a large capacity inductive load, we developed a TRIAC PWM module. And we also developed a sequential start control system preventing simultaneous starting of the inductive loads within a same power network. According to the experimental results with the proposed control system, the voltage-dip and inrush current could be effectively attenuated such that they can meet the related international standards and resolve the issues associated with simultaneous starting of multiple inductive loads. By employing this system, power cost usually implemented by the estimation of peak power consumption can be reduced and the power quality of a power distribution system connected to the inductive load network can be stabilized efficiently.

• Journal of the Korean Ceramic Society
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• v.36 no.8
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• pp.791-798
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• 1999

The preparation method of yttria-stabilized zirconia(YSZ) thin film for an anode support type solid oxide fuel cell(SOFC) by electrophoretic deposition(EPD) and dip-coating was studied. And the difference in both preparation method was investigated through basic understanding of processing parameters which may significantly affect weight microstruxcture and defect of film. In dip-coating the thickness of film increased with time until 30 s and then the weight of film decreased with time due to particle falling off from the coagulated film. In EPD although the weight of film increased with time and applied constant-current sagging of the film was observed when the applied current was less that 0.035 mA/$cm^2$ and more than 120 s. Since YSZ thin film by EPD on porous substrate was dense smooth and homogeneous it was expected to be suitable for the electrolyte of an anode support type SOFC.

• Korean Journal of Poultry Science
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• v.17 no.2
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• pp.115-122
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• 1990

Effects of 7.5% potassium sorbate and/or 1% ascorbic acid dip on she]f-life of chicken parts stored at $4^{\circ}C$ was investigated. There was no remarkable difference in the microbial growth between 1% ascorbic acid dipped chicken parts and untreated chicken parts. Off-odor developed after 8 days storage and bacterial spoilage was occurred after 12 days storage. 7.5% potassium sorbate dip significantly retarded mesophilic and psychrotrophic counts compared with untreated, markedly reduced growth rate of Enterobacteriaceae. Fecal coliforms were not detected and bacterial spoilage was not occurred until 21 days storage. off-odor developed after 19 days storage and color was not significantly deteriorated until 21 days storage. Additional effect of 7.5% potassium sorbate and 1% ascorbic acid dip was found on retarded mesophilic, psychrotrophic and Enterobacteriaceae counts compared with 7.5% potassium sorbate dip alone. Bacterial spoilage was not occurred until 21 days storage. off-odor developed after 21 days storage and color was not significantly deteriorated until 21 dayss storage.

• Journal of Surface Science and Engineering
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• v.51 no.4
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• pp.224-230
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• 2018

In this study, Mg films were prepared on hot dip aluminized steel (HDA) by using a sputtering method as a high corrosion resistance coating. The corrosion resistance of the Mg films was improved by controlling the morphology and the crystal structure of films by adjusting the Ar gas pressure during the coating process. Anodic polarization measurement results confirm that the corrosion resistance of the Mg films was affected by surface morphology and crystal structure. The corrosion resistance of the Mg coated HDA specimen increased with decreasing crystal size of the Mg coating and it was also improved by forming a film with denser morphology. The crystal structure oriented at Mg(101) plane showed the best corrosion resistance among crystal planes of the Mg metals, which is attributed to its relatively low surface energy. Neutral salt spray test confirmed that corrosion resistance of HDA can be greatly improved by Mg coating, which is superior to that of HDG (hot dip galvanized steel). The reason for the improvement of the corrosion resistance of Mg films on hot dip aluminized steel was due to the barrier effect by the Mg corrosion products formed by the corrosion of the Mg coating layer.

• Journal of Surface Science and Engineering
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• v.55 no.6
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• pp.448-459
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• 2022

Generally, steel is the most commonly used in the industry because of good strength, processability and cost-effectiveness. Steel can be surface-treated such as coating or used as an alloy by adding elements such as Cr, Ni, Zr, and Al to increase corrosion resistance. However, even if steel is used in same environment corrosion resistance is sharply lowered when it is exposed to a high temperature for a fixed or extended period of time due to an overload or other factors. In particular, the use of hot-dip aluminized plated steel, which is used in high-temperature atmospheres, is increasing due to the surface Al₂O₃ oxide film. This steel necessitates an urgent solution as issues of corrosion resistance limitations often appear. It is an important issue that not only cause analysis but also the research for the surface treatment method that can be solved. Thus, in this study, Cr in which it is expected to be effective in corrosion resistance and heat resistance attempted to deposit on hot dip aluminized plated steel with PVD sputtering. And it was possible to present the surface treatment application of various types of industrial equipment exposed to high temperature and basic design guidelines for use by confirming the corrosion resistance of hot dip Al-Si plated steel with Cr film deposited at high temperature.

• Journal of Korean Society on Water Environment
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• v.24 no.3
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• pp.354-364
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• 2008

The variability in the phosphorus concentrations and the decomposition rates of organic phosphorus were measured in two rivers, the Youngsan River and the Sumjin River through four surveys in June, August and December of 2006 and February of 2007. Water samples were incubated for 20 days in a dark incubator and the change of forms of phosphorus (POP, DOP, DIP) were analyzed. By fitting the change to four types of models the decomposition rates of organic phosphorus were determined. The mean total organic phosphorus (TOP) decomposition rate coefficients in the Youngsan River and the Sumjin River were $0.036day^{-1}$ and $0.035day^{-1}$, respectively. In POP$\rightarrow$DIP model, the average decomposition rate coefficients in the Youngsan River and the Sumjin River were 0.049 and $0.035day^{-1}$, respectively. The average POP decomposition rate coefficients of POP$\rightarrow$DOP$\rightarrow$DIP model were $0.042day^{-1}$ and $0.038day^{-1}$ in the Youngsan River and Sumjin River respectively while the mean DOP decomposition rate coefficients were $0.255day^{-1}$ and $0.244day^{-1}$, respectively. In the Youngsan River, the mean POP$\rightarrow$DOP decomposition rate coefficient and POP$\rightarrow$DIP decomposition rate coefficient of POP$\rightarrow$DOP$\rightarrow$DIP, POP$\rightarrow$DIP model were $0.039day^{-1}$ and $0.007day^{-1}$, respectively. And in the Sumjin River, the above decomposition rate coefficients were $0.031day^{-1}$ and $0.004day^{-1}$, respectively. The decomposition rate coefficients measured in this study might be applicable for modeling of river water quality.

• Korean journal of applied entomology
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• v.45 no.1 s.142
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• pp.51-57
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• 2006

Culex pipiens complex larvae were found at the septic tanks in Busan and Ulsan cities located in South-eastern area of Korean peninsula. The larvae were collected in 25, 35 and 75 septic tanks out of 3,527, 622 and 1,111 septic tanks which the breeding rates were averages of 0.7%, 5.6% and 6.8% in Busan from January to May, 2003; Busan from February to March, 2004; and Ulsan from January to April, 2005, respectively. The average numbers of the mosquitoes in the tanks were 38.8, 14.9 and 13.7 larvae/dip with a 355-ml dipper. The larval densities were from 25.4 larvae/dip in January to 43.7 larvae/dip in April. 2003 which were not significantly different between them. It was the first report to find mosquito breeding at septic tink in Republic of Korea. Culex pipiens larvae were found in 6 out of 379 septic tanks at complex buildings (over $2,000m^2$ in size) in Ulsan from June to September, 2005, having an average of 1.6% for mosquito breeding rate. The mosquito larvae were collected in 8 and 530 septic tanks out of 210 and 3,729 septic tanks at large (over 300 homes) and small apartments (below 300 homes) with 3.8% and 14.2% of the average breeding rates, respectively At the septic tanks of private houses for below 50 persons, 708 out of 7,178 septic tan had Cx. pipiens larvae and pupae with 9.9% of the average breeding rate. Total average of the mosquito breeding rate was 10.9% of the investigated septic tanks of residential buildings in Ulsan. The number of mosquito larvae in the septic tanks were 15 to 75 larvae/dip. The bent net sets of septic tanks prevented from mosquito breeding to the rate of 93.1%.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.2
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• pp.162-165
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• 2003

In order to study the secretion of the human urokinase-type plasminogen activator, u-PA, from the yeast yarrowia lipolytica, three kinds of integrative expression vector were constructed. These vectors differed only in their secretion control legions, pre-, pre-dip-(dipeptide Stretch) or pre-dip-pro sequences of the alkaline extracellular protease, which were joined inflame to the human u-PA cDNA. The recombinant Y. lipolytica Strains, transformed with the expression vectors, secreted the hyperglycosylated u-PA. A fibrin plate assay of the culture supernatants showed that the hyperglycosylated u-PA proteins could catalyze fibrinolysis, and that the pre-dip sequence was the most efficient secretory signal for the secretion of the u-PA from Y. lipolyica. This result suggests that Y. lipolytica can be developed as a potential host for the production of recombinant human u-PA.

• ETRI Journal
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• v.27 no.3
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• pp.280-288
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• 2005

This paper presents an efficient algorithm for using the two-axis magnetic compass in portable devices. The general magnetic compass module consists of a three-axis magnetic compass and a two-axis inclinometer to calculate tilt-compensated azimuth information. In this paper, the tilt error is compensated using just a two-axis magnetic compass and two-axis accelerometer. The third-axis data of the magnetic compass is estimated using coordinate information that includes the extended dip angle and tilt information. The extended dip angle is estimated during the normalization process. This algorithm can be used to provide the tilt-compensated heading information to small portable devices such as navigation systems, PDAs, cell phones, and so on.

• Geomechanics and Engineering
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• v.11 no.2
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• pp.269-288
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• 2016

The jointed rock mass behavior often plays a major role in the design of underground excavation, and their failures during excavation and in operation, are usually closely related to joints. This research attempts to evaluate the effects of two basic geometric factors influencing tunnel behavior in a jointed rock mass; joints spacing and joints orientation. A hybridized indirect boundary element code known as TFSDDM (Two-dimensional Fictitious Stress Displacement Discontinuity Method) is used to study the stress distribution around the tunnels excavated in jointed rock masses. This numerical analysis revealed that both the dip angle and spacing of joints have important influences on stress distribution on tunnel walls. For example the tensile and compressive tangential stresses at the boundary of the circular tunnel increase by reduction in the joint spacing, and by increase the dip joint angle the tensile stress in the tunnel roof decreases.