• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.3
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• pp.63-70
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• 2010

Based on the known results of the expected busy periods for the triadic Min (N, T, D) and Max (N, T, D) operating policies applied to a controllable M/G/1 queueing model, a relation between them is constructed. Such relation is represented in terms of the expected busy periods for the simple N, T and D, and the dyadic Min (N, T), Min (T, D) and Min (N, D) operating policies. Hence, if any system characteristics for one of the two triadic operating policies are known, unknown corresponding system characteristics for the other triadic operating policy could be obtained easily from the constructed relation.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.240-245
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• 2004

Tensile properties of hard coating material, TiN, were evaluated using micro-tensile testing system. TiN has been known as a hard coating material commonly used today. Micro-tensile testing system consisted of a micro tensile loading system and a micro-ESPI(Electronic Speckle Pattern Interferometry) system. Micro-tensile loading system had a maximum load capacity of 500mN and a resolution of 4.5 nm in stroke. TiN thin film $1{\mu}m$ thick was deposited on the Si wafer pre-deposited of $Si_3N_4$ film substrate by the closed field unbalanced magnetron sputtering (CFUBMS) process. Three kinds of micro-tensile specimen with the respective width of $50{\mu}m$, $100{\mu}m$ and $500{\mu}m$ were fabricated by MEMS process. The mechanical properties including tensile strength and elastic modulus were determined using the micro-tensile testing system and compared by those obtained by nano-indentation

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.6
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• pp.41-48
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• 2003

Nitrogen removal rate and emergent plant growth were investigated of a free-water-surface constructed treatment wetland system, whose dimensions were 31m in length and 12m in width. The system was constructed on floodplain in the Kwangju Stream from May to June 2001. Cattails(Typha angustifolia) were transplanted from natural wetlands and their stems were cut at about 40cm height from their bottom ends. Water of the Kwangju Stream were funneled into the system by gravity flow and its treated effluent was discharged back into the stream. The average height of the cattail stems was 45.2cm in July 2001 and 186cm in October 2001. The number of stems averaged 22 stems/$m^2$ in July 2001 and 52 stems/$m^2$ in September 2001. Volume and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow and outflow averaged 40.01 and 39.55 $m^3$/day, respectively. Hydraulic detention time was about 1.5 days. Average nitrogen uptake by cattails was 69.31 $N\;mg\;m^{-2}\;day^{-1}$. Removal rate of $NO_3-N$, $NH_3-N$ and T-N averaged 195.58, 53.65 and 628.44 $mg\;m^{-2}\;day^{-1}$, respectively. The average removal rate of T-N was about 39%.

• Journal of Surface Science and Engineering
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• v.43 no.5
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• pp.238-242
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• 2010

In the present work, the influence of oxide on the Cr-Si-N coatings was investigated for the Cr-Si-O-N coatings on AISI 304 and Si wafer deposited by hybrid system, which combines the DC magnetron sputtering technique and arc ion plating (AIP) using Cr and Si target in an $Ar/N_2/O_2$ gaseous mixture. As the O content in the Cr-Si-N coatings increased, the diffraction patterns of the Cr-Si-O-N coatings showed CrN and $Cr_2O_3$ phases. However, as the O content increased to 28.8 at.%, diffraction peak of $Cr_2O_3$ was disappeared in the Cr-Si-O-N coating. The $d_{200}$ value was decreased with increasing of O content. The average grain size increased from about 40 nm to 65 nm as the O content increased. The maximum micro-hardness of the Cr-Si-O-N coating was obtained 4507 Hk at the O content of 24.8 at.%. The average friction coefficient of the Cr-Si-O-N coatings was gradually decreased by increasing the O content and the average friction coefficient decreased from 0.37 to 0.25 by increasing the O content. These results indicated that amorphous phase was increased in the Cr-Si-O-N coatings by increasing of O content.

• Journal of Korean Society of Water and Wastewater
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• v.8 no.2
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• pp.1-11
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• 1994

This study was conducted to develop a new RBC process available for the effective removal of organic matters and nitrogen in sewage. The RBC process for the oxidation organic compounds and nitrification was designed to occur at the 1st-stage and next-stage RBC respectively. Then nitrified water was recycled to the denitrifying RBC located at the lower part of the 1st-stage RBC. Some results were summarized as follows. 1. The loading limitation was represented as $60g{\cdot}COD/gm^2/day$ in experiment of simultaneous removal of organic matter and nitrogen. The maxmum COD % removal was 85% at the load $35g{\cdot}COD/m^2/day$. 2. The $NO_3-N$ % removal was approximately 80% at the load $60g{\cdot}COD/m^2/day$ and the maximum $NO_3-N$ remaval rate was $3.9g{\cdot}COD/m^2/day$ and the overall C/N ratio of 11.0 as required to achive 80% of $NO_3-N$% removal. 3.$NO_3-N$ removal rate was rapidly decreased above the load $7g{\cdot}NH_4{^+}-N/m^2/day$ and the maximum $NO_3-N$ removal rate was $3.7g{\cdot}NO_3-N/m^2/day$. 4. Irrespective of the recycle ratio, the COD % removal at the system of 2-stage RBC unit was nearly constant as 89% while the maximum one in the 1st-stage unit was 77% in the case of 50% recycle. 5. The maximum COD % removal in the 3-stage RBC system was 93% while 1st-stage one being 80%, under the $NH_4{^+}-N$ load of $7.4g/m^2{\cdot}d$. Also maximum percentage of nitrification and denitrification was 69% and 41% respectively, under the same $NH_4{^+}-N$ load.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.68 no.3
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• pp.197-206
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• 2023

This study was conducted to investigate how maize (Zea maize L.) growth and yield were affected by irrigation and fertigation using a subsurface drip system. The system consisted of a buried (40 cm underground) drip pipe that can be used in a semi-permanent manner without affecting agricultural work on the ground. The amount of water required for the fertigation treatment was determined to be 24.3 tons 10a^-1 for the sandy loam soil used in this experimental field. Fertigation treatments based on the previously calculated 24.3 tons 10a^-1 were carried out as topdressing applications. They were applied through the subsurface drip system with the following fertilizer concentration (nitrogen only, written in kg 10a^-1: N 4, N 6, N 8, N 10 ). The other treatments were irrigation only and control (non-treatment). The results indicated that the N 8 treatment was the most effective, increasing yield by 30% and 14% compared with the control and irrigation treatments, respectively. These results highlight the effectiveness of fertigation (N 8 kg 10a^-1) at V6 and R1 stage as a form of topdressing fertilization using a subsurface drip system for achieving a high yield and stable maize production.

• Korean Journal of Clinical Pharmacy
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• v.23 no.3
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• pp.256-268
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• 2013

Objective: To study the attitudes and awareness of healthcare professionals (physicians, pharmacists, nurses and others) toward the Pharmacovigilance system and experience for adverse drug reactions (ADRs) from a Single University Hospital in Deajeon. Methods: A survey was performed using a structured questionnaire involving 360 health-care professionals at the hospital between $1^{st}$ November and $16^{th}$ November, 2012. Results: Sixty-five percent (n=235) of all respondents were experienced incidences of ADRs for their patients and 55.8% (n=201) knew the ADR Spontaneous Reporting System in the hospital. However, three-fourths (n=273, 75.8%) of respondents did not know the existence of the Korean Association of Regional Pharmacovigilance Centers (KARP) and 61.7% (n=222) were unaware of the obligation of ADR report from KFDA in cases of serious ADRs. About 83% (n=299) answered that the electronic ADR report system of the hospital was helpful while their work and most (n=336, 93.3%) agreed on the necessaries of the promotion and education about ADR. Conclusion: Seventy-five percent (n=271) of respondents wanted to continue the work for evaluation and feedback for ADRs reported in the hospital. However, the barriers to reporting ADR were; inconvenient ADR reporting system and the lack of time to report ADRs. This study showed that the easier ADR reporting system and education and promotion about ADRs for health-care providers are needed to improve the ADR reporting.

• Korean Journal of Environmental Agriculture
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• v.21 no.4
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• pp.274-278
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• 2002

Nitrate removal rate in three wetland cells was examined. The acreage of each cell was 150 $m^2$. They were a part of a stream water treatment demonstration system which was composed of two ponds and six wetland cells. Earth works far the pond-wetland system were finished from April 2000 to May 2000 and reeds were planted in the three cells in May 2001. Waters of Sinyang Stream flowing into Kohung Esturiane Lake located southern coastal area of Korean Peninsula were pumped into a primary pont Effluents from a secondary pond were funneled into the three cells. Volumes and water quality of inflow and outflow were analyzed from July 2001 through December 2001. Inflow and outflow averaged 20 $m^3/d$ and 19.3 $m^3/d$, respectively. Hydraulic retention time was 1.5 days. Average influent and effluent nitrate concentration was 2.30 mg/L, 1.75 mg/L, respectively. Nitrate removal rate in the three cells averaged 80.9 $mg/m^2/day$. Seasonal changes of nitrate retention rates were closely related to those of wetland temperatures. Full growth of reeds within a few years can develope litter-soil substrates beneficial to the denitrification of nitrate, which may lead to increases of the nitrate retention rates.

• Journal of the Korean Ceramic Society
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• v.23 no.1
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• pp.33-43
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• 1986

The synthesis of high-purity AlN by a vapor-phase reaction was investigated using the $NH_3-AlCl_3-H_2$ reacting system. The theoretical yields of AlN were determined from th thermodynamic equilibrium composi-tions. It was shown that the yields above 90% could by obtained even in the range of relatively low temper-ature of 600-1200K. The reaction temperature and the initial amounts/ratios of the reacting gases showed significant effects on the yields but the total pressure did not. The experimental results showed that a high-purity AlN having a needle shape was the only product as a solid phase and its amount produced increased with the reaction temperature. While the degree of agglmera-tion of the synthesized AlN increased with the reaction temperature the size of each particle consisting of the agglomerates was independent of the temperature but grew from 0.09 to 0.115${\mu}{\textrm}{m}$ with the flow rate of NH3. These experimental results were compared with the theoretical aspects for the synthesis of a high-purity AlN.

• Journal of environmental and Sanitary engineering
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• v.11 no.3
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• pp.63-68
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• 1996

This study was to discuss limiting factors influenced on the removal efficiencies of nitrogenous compounds investigated using the polypropyrene media which was to attach microorganism in order to apply the fixed-biofilm process. The main limiting factors are the hydraulic retention time (HRT), C/N ratio, $COD/NO_{3}-N$ ratio and temperature. The hydraulic retention time HRT were 6, 8, 10, 12 hrs and the C/N ratio range was 2.5-9.5. The $COD/NO_{3}-N$ ratio range was 3.2-21.9 and the temperature were 15, 20, 25, 30, $35^{\circ}C$, respectively. The results of this study are summerized as follows. 1. Hydraulic retention time (HRT) to obtain removal efficiencies of T-N higher than 85% had to be 10 hrs above. 2. The removal efficiencies of T-N decreased at C/N ratio from 6.2 to 4.8 in this anoxic-contact aeration system. 3. Denitrification rate decreased at $COD/NO$_{3}$-N$ ratio from 8.0 to 5.0 4. As temperature increased, removal efficiencies of T-N increased.