대량의 각혈로 사망한 장티푸스 1예

한상우,유진홍,권순석,김성훈,박지찬,홍은정,최경성,박용완,장준희,안지원,박유경,강지영,박상미,신완식 대한감염학회 2004 감염과 화학요법 Vol.36 No.5

We experienced a 25 year-old male patient with typhoid fever complicated with massive hemoptysis. Pulmonary complication in typhoid fever is very rare and to our knowledge, there has been no report of hemoptysis as a main cause of death with this disease. We herein report a rare case of typhoid fever.

실험계획법을 이용한 능동형 미소혼합기의 근사최적화

박재용,이원구,유진식,김용대,한석영,맹주성 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

An active micro-mixer, which was composed of an oscillating micro-stirrer in the microchannel to provide rapid, effective mixing at high flow rates was analyzed. The effects of molecular diffusion and disturbance by the stirrer were considered with regard to two types of mixer models: the simple straight microchannel and microchannel with an oscillating stirrer. Two types of mixer models were studied by analyzing mixing behaviors such as their interactionafter the stirrer. The mixing was calculated by Lattice Boltzmann methods using the D2Q9 model, In this study, the time-averaged mixing index formula was used to estimate the mixing performance of time-dependent flow. The mixing indices of the two models were compared. From the results, it was found that the mixer with an oscillating stirrer was much more enhanced and stabilized. Therefore, an approximate optimization of an active micro-mixer with an oscillating stirrer was performed using Kriging method with OLHD(Optima1 Latin Hypercube Design) in order to obtain a optimum solution. The design parameters were established as the frequency, the length and the angle of the stirrer, and the optimal values were determined to be 1.0346, 0.66D and ±45°, respectively. It was found that the mixing index of the optimal design increased by 88.72% compared with that of the original design.

시판 동물성 식품의 저장온도 및 저장기간별 세균균속의 변화

박석기,이용욱,윤희정 대한보건협회 2000 대한보건연구 Vol.26 No.1

It is very important to prepare the sanitation criteria for the animal foods through the microbiological examination and the investigation of tendency to change of the organisms according to the storage temperature and period. As the results of identification of total 110 genera isolated from commercial animal foods, 15 genera were identified and predominant genera were Staphylococcus(29.1%), Pseudomonas (13.6%) and Enterococcus(12.7%) and followed by Enterobacter, Lactobacillus, Achromobacter, Aeromonas, Escherichia, Micrococcus, Bacillus, Klebsiella, Serratia and yeast. As the results of identification of 1323 isolates from commercial animal foods stored at 10℃, 20℃ and 30℃, 21 genera were identified and Staphylococcus(22.5%), Enterococcus(15.9%), Pseudomonas(15.9%), Bacillus(10.3%) were predominant. The predominant genus among 405 isolates from commercial animal foods stored at 10℃ was Pseudomonas(28.9%), followed by Staphylococcus(19.8%), Enterococcus(16.0%) and Bacillus(11.1%). The predominant genus among 483 isolates from commercial animal foods stored at 20℃ was Staphylococcus(23.4%), followed by Enterococcus(16.0%) and Pseudomonas(11.1%) but the predominant genera among 436 isolates from commercial animal foods stored at 30℃ was Staphylococcus(23%), followed by Enterococcus(15.4%) and Bacillus(11%).

순차적 크리깅기법을 이용한 미소혼합기의 최적화

박재용,유진식,황승민,임민규,오영규,김용대,한석영,맹주성 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

An active micro-mixer, which is composed of an oscillating micro-stirrer in the micro-channel to provide effective mixing was optimized. The effects of molecular diffusion and disturbance by the stirrer were considered with regard to two types of mixer models: the simple straight micro-channel and micro-channel with an oscillating stirrer. Two types of mixer models were studied by analyzing mixing behaviors such as their interaction after the stirrer. The mixing was calculated by Lattice Boltzmann methods using the D2Q9 model. In this study, the time-averaged mixing index formula was used to estimate the mixing performance of time-dependent flow. The mixing indices of the two models were compared. From the results, it was found that the mixer with an oscillating stirrer was much more enhanced' and stabilized. Therefore, an approximate optimization of an active micro-mixer with an oscillating stirrer was performed using Kriging method with OLHD (Optimal Latin Hypercube Design) in order to determine the optimal design variables. The design parameters were established as the frequency, the length and the angle of the stirrer. The optimal values were obtained as 1.5754, 0.803D and ±45°, respectively. It was found that the mixing index of the optimal design increased by 83.36% compared with that of the original design.

체적제어를 이용한 신뢰성 기반 위상 최적화

박재용,황승민,임민규,오영규,박재용,한석영 한국공작기계학회 2009 한국공작기계학회 춘계학술대회논문집 Vol.2009 No.-

This paper presents a reliability-based topology optimization (RBTO) using bi-directional evolutionary structural optimization (BESO). An actual design involves uncertain conditions such as material property, operational load and dimensional variation. Deterministic topology optimization (DTO) is obtained without considering of uncertainties related to the uncertainty parameters. However, the RBTO can consider the uncertainty variables because it has the probabilistic constraints. In this paper, the reliability index approach (RIA) is adopted to evaluate the probabilistic constraint. RBTO based on BESO starting from various design domains produces a similar optimal topology each other. Numerical examples are presented to compare the DTO with the RBTO.

크리깅 기법을 이용한 마이크로 믹서의 최적 설계

박재용,김상락,이원구,유진식,김용대,한석영,맹주성 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

An active micro-mixer, which was composed of an oscillating micro-stirrer in the microchannel to provide rapid, effective mixing at high flow rates was analyzed. The effects of molecular diffusion and disturbance by the stirrer were considered with regard to two types of mixer models: the simple straight microchannel and microchannel with an oscillating stirrer. Two types of mixer models were studied by analyzing mixing behaviors such as their interactionafter the stirrer. The mixing was calculated by Lattice Boltzmann methods using the D2Q9 model. In this study, the time-averaged mixing index formula was used to estimate the mixing performance of time-dependent flow. The mixing indices of the two models were compared. From the results, it was found that the mixer with an oscillating stirrer was much more enhanced and stabilized. Therefore, an optimum design for a dynamic micro-mixer with an oscillating stirrer was performed using Kriging method in order to obtain a optimum solution. The design parameters were established as the frequency, the length and the angle of the stirrer, and the optimal values were determined to be 2.0932, 0.8D and ± 75°, respectively. It was found that the mixing index of the optimal design increased by 88.47% compared with that of the original design.

티타늄 상에 강유전성 barium titanate 박막 형성과 분극처리에 의한 유사체액 내에서의 calcium phosphate 생성 증진

박영준,이용렬,황규석,김은주,임용무,이기헌 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.2

This study was performed to fabricate a ferroelectric barium titanate (BaTiO₃, BTO) thin film on Ti substrate and to evaluate the effect of poling treatment for the improvement of calcium phosphate (Ca-P) formation. BTO thin-film was spin-coated on Ti substrate by dipping-pyrolysis technique using coating sol obtained by mixing Ba-naphthenate and Ti-naphthenate as starting substances. Pre-heating temperature of the BTO thin film was performed at 500℃ because organic-solvent was completely volatilized without any crystal growth, and the final heat treatment was performed at 600, 650, 700, 750, 800, 850℃, respectively. By repeating the coating and pre-heating procedure gor 20 times, homogeneous thin film of 0.7㎛ thickness could be fabricated, and it performed well during the poling treatment without breakdown. The final heating treatment of the BTO thin film at 750℃ produced a homogeneous crystalline structure without heterogeneous TiO₂formation, which was confirmed by field emission scanning electron microscope (FE-SEM) and X-ray diffraction analyser (XRD). An average grain size of 20∼30 ㎚ were confirmed by SEM observation. The final heat-treated BTO thin-films were polarized (Ep = 5 V/㎛) from 160℃ to 25℃ in heating chamber for 2 h. The negatively poled BTO thin film (N-BTO), non-poled BTO thin film (BTO), Ti substrate (Ti), and 600℃ heat-treated Ti (Ti-O) were immersed in SBF and Eagle's MEM solution for 15 days at 37℃. After the immersion period, the morphological and compositional changes of the surfaces were investigated using a FE-SEM and an energy dispersive X-ray spectrometer (EDX). After immersion in simulated body fluid (SBF), sodium chloride (Nacl) crystals were formed on Ti, Ti-O, and BTO surfaces due to anion adsorption (Cl), while Ca-P crystals were formed on N-BTO surfaces. We assumed that rapidly adsorded cations (Ca²□ ions) on the negatively charged surface at the initial stage acted as nuclei for the formation of Ca-P crystals. In MEM, sodium chloride (NaCl) was formed on Ti, and Ca-P layer including NaCl was formed on Ti-O. Weak and sparse Ca-P layers were formed on BTO, while thick, homogeneous, and dense Ca-P layer was formed on N-BTO, which was confirmed by FE-SEM and EDX. These results demonstrated that introducing a N-BTO on Ti is an effective method for the improvement of Ca-P formation in SBF and MEM. In conclusion, negatively charged ferroelectric BTO thin-film on Ti would improve the possibility of implant osseointegration.

배기 가스 정화용 금속 담체의 브레이징시 제조 변수의 영향

朴大鎭,金容奭 弘益大學校 科學技術硏究所 2000 科學技術硏究論文集 Vol.11 No.-

The effects of brazing temperature and time, and the thickness of filler metal on the joint microstructure of metallic catalytic convertor were investigated. Especially, the formation of brittle eutectic structure was examined. In general, it was found that processing conditions which promote the diffusion of Si in the filler metal reduce the formation of the eutectic structure. The condition includes the higher bonding temperature, longer brazing time, thinner filler metal. The higher bonding temperature and longer brazing time, however, led to extensive dissolution and degradation of the catalytic material. Thus, it was found that the brazing conditions using thinner filler metal at moderate brazing temperature and time are most effective in preventing the formation of the brittle eutectic structure in the brazed joint of the catalytic convertor.

기업의 기부·접대비 지출행위에 관한 연구

홍효석,김동훈,박용철 진주산업대학교 1999 산업과학기술연구소보 Vol.- No.6

This study is to analyze the relation factors of corporate contribution and entertainment expenses. We try to seek to find out the motives of corporate contributions and entertainment expense for describing factors. Previous study is reported different result for our study. Then this study reexamines about this more analytical approach. We select 2,062 sample firms during 1991-1996 and result using correlation analysis is as follows. Contribution and entertainment expense shows a significantly positive with firm size that is corporate sales except for 1991. The contribution and entertainment expense has a significant positive relation with cash flow, industry contribution level, pre-period contribution level, advertisement, research and development cost, effective tax rate, retained earnings. In the case of debt ratio, the result shows significantly negative relation. Therefore we assert that the contribution and entertainment expenses are made for earnings management.

부실기업의 이익조정에 관한 연구

홍효석,박용철 진주산업대학교 1998 論文集 Vol.37 No.-

The purpose of this study is to identify whether the insolvent firm's income adjustment phenomenon. We think that these firms have an incentives for income adjustment with discretionary accruals(DA). The estimation coefficient of this study uses 7 years of accruals before bankruptcy and testing tools are modified Jones model which is known to detect income adjustment. Empirical test are conducted using 45 sample firms during 1982-1994. The result is as follows. Discretionary accruals from t=-2 to t=-1 are adjusted incomes significantly positive but the result of period(t=0) is reversed. These results are the evidence that the insolvent firm manage the earnings through discretionary accruals previous to bankruptcy.