On the Strengthening Effects Affecting Tensile and Low Cycle Fatigue Properties of Low-Alloyed Seismic/Fire-Resistant Structural Steels

Jung‑Ho Sim,Tae‑Yeong Kim,Jun‑Yeon Kim,Chi‑Won Kim,Jun‑Ho Chung,Joonoh Moon,Chang‑Hoon Lee,Hyun‑Uk Hong 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.2

In the present study, low carbon ferritic and bainitic steels with different contents of Mo, Ti, and Nb were designed for bothseismic and fire-resistant applications. The microstructure of steels containing 0.3 wt% Mo–0.02 wt% Nb (‘A’ hereinafter)was mainly composed of bainite. By contrast, the microstructure of steels with 0.2 wt% Mo–0.13 wt% Ti (‘B’ hereinafter)consisted of ferrite with a high density of nano-sized (Ti,Mo)-rich MX precipitates. The results showed that the bainiticmicrostructure (‘A’ steel) was quite favorable to high-temperature strength and thermal stability. The yield strength of ‘A’ steelat both room and 600 °C temperatures increased consistently with increasing thermal exposure time (600 °C/200–1000 h),since the precipitation of NbC particles occurred while maintaining bainitic ferrite platelets with a high density of dislocationsduring exposure. In the ‘B’ steel, the formation of nano-sized (Ti,Mo)-rich MX particles was effective to impededislocation movement, leading to excellent plasticity (lower yield ratio) at room temperature. However, their contributionto precipitation hardening was not so much at 600 °C, as compared to the bainitic strengthening. During low cycle fatiguetests at room temperature, the main different feature between the two steels is that the ‘A’ steel showed cyclic softeningwhile cyclic hardening was evident in the ‘B’ steel. The bainitic microstructure showed a better fatigue life due to increasedductility manifested by cyclic softening, by which dislocation cell was developed.

발열을 동반한 호중구감소증에서 Cefepime 단독투여와 Ceftazidime 및 Tobramycin 병합투여의 효능비교

정현욱,채제욱,강미라,양정채,문치숙,기현균,장현하,오원섭,김기현,백경란,이남용,송재훈 대한감염학회 2004 감염과 화학요법 Vol.36 No.6

목적 : 국내에서 발열을 동반한 호중구감소증이 있는 악성 종양환자에게 경험적 항생제로 베타락탐계 항생제와 아미노배당체의 병합요법의 사용이 일반적이다. Cefepime은 광범위 항균 작용을 가지고 있어, 그람 음성균 뿐만 아니라 그람 양성균에 대해서도 우수한 효과를 나타낸다. 재료 및 방법: 발열을 동반한 호중구감소증이 있는 악성 종양환자를 대상으로 무작위, 공개, 비교 연구를 시행하였다. 대상 환자를 무작위로 cefepime 단독요법군과 ceftazidime 및 tobramycin 병합요법군으로 나누어 투여하고 각각의 임상적 효능과 안전성을 비교하였다. 구강및 인후 점막염이 있는 환자에서 분리된 녹색 연쇄알 구균에 대한 항생제 내성 정도를 조사하였다. 결과 : 대상환자 89명 중 CA 투여군이 48예(53.9%), CT 투여군이 41예(46.1%)이었다. 발열의 유형별로 MDI는 18예(20.2%), CDI는 9예(10.1%), UF는 62예(69.7%)로 두 군 간에 차이가 없었다. CA 투여군과 CT 투여군의 임상적 호전률은 시험약 투여 후 2-4일째 각각 91.7%, 85.4% (P=0.31), 치료 종료 시 각각 91.7%, 100% (P=0.15)로 두 군간에 유의한 차이가 없었다. 치료 종료 시 CA 투여군과 CT 투여군의 세균학적 소실률은 모두 100%로 두 군간의 유의한 차이가 없었다(P=0.78). 점막염이 있는 환자로부터 녹색 연쇄알 구균이 분리된 경우는 25예(28.1%)이었으며, 분리된 녹색 연쇄알 구균은 penicillin, ceftriaxone, cefepime, vancomycin에 모두 감수성을 보였다. 약제 관련 이상 반응의 발생 빈도도 두 군간에 유의한 차이가 없었다. 결론 : 발열을 동반한 호중구감소증이 있는 악성 종양환자의 경험적 항생제로서 cefepime 단독요법은 ceftazidime 및 아미노배당체의 병합요법만큼 효과적이고 안전하였다. Background : Broad-spectrum antibiotic therapy has been recommended as an empirical regimen in cancer patients with febrile neutropenia. Cefepime is a fourth generation cephalosporin with good activity against both gram-positive cocci and gram-negative bacilli. Materials and Methods : To compare the efficacy and safety of cefepime alone with ceftazidime plus tobramycin as empirical regimen for adult cancer patients with febrile neutropenia, a randomized, open label, comparative trial was performed. If the patient showed clinical improvent 72 hours, antibiotic could be changed to oral ciprofloxacin. Clinical and microbiological responses were determined at 72 hours and at the end of therapy. To investigate the antimicrobial resistance of viridans streptococci, swab cultures were obtained from throat in all enrolled patients and antimicrobial susceptibility tests were performed by using microdilution method according to the NCCLS. Results : A total of 89 patients were enrolled. Forty-eight patients received cefepime alone (CA), and 41 patients received ceftazidime plus tobramycin (CT). Demographic and baseline clinical characteristics were similar in both groups (P>0.05). The initial clinical success rate at day 2-4 in group CA (91.7%) was similar with that in CT group (85.4%) (P=0.31). At the end of therapy, the final clinical success rate in CA group (91.7%) was similar to that in CT group (100%) (P=0.15). In 18 patients, with microbiologically defined infections, the eradication rate was 100% in both groups. Adverse events including liver dysfunction (21.3%) and renal dysfunction (2.2%), were similar in both groups (P=0.87). Viridans streptococci were isolated from the throat cultures in 25 cases, and all of these strains were susceptible to penicillin (MIC_(90) 0.12 ㎍/mL), cefepime (1 ㎍/mL), and vancomycin (0.12 ㎍/mL). Conclusion : Efficacy and safety of cefepime monotherapy was comparable to the combination of ceftazidime and tobramycin. It could be used as an alternative empirical regimen for treating cancer patients with febrile neutropenia.

스프레드시트와 Green 정리를 이용한 철근 콘크리트 단주의 해석 및 설계

진치섭,한상중,엄장섭,이승훈 釜山大學校生産技術硏究所 1998 生産技術硏究所論文集 Vol.55 No.-

구조물 설게에서, 압축과 2축 휨을 동시에 받는 기둥 설계를 자주 접하게 된다. 이러한 부재의 해석과 설계는, 모멘트 평형에 따른 여러 변수들의 값을 동시에 구하기 위하여 반복적인 작업이 필요하기 때문에 많은 시간을 요구한다. 본 연구에서는 압축과 2축 휨을 받는 철근 콘크리트 단주를 해석 및 설계할 수 있는 컴퓨터 프로그램 COL2를 개발하였다. 프로그램 COL2는 스프레드시트 프로그램 중의 하나인 엑셀을 이용한 사용자 위주 환경의 프로그램으로 개발되었다. Green정리를 사용하여 임의 형상의 역학적 특성을 계산하였다. In structural design, columns subjected to combined compression and biaxial bending are frequently encountered. The analysis and design of such members, are both time consuming and demanding because an iterative procedure is reuqired in order to simultaneously evaluate a number of variables to achieve moment equilibrium. A computer program COL2 is developed to analyze and design reinforced concrete short columns subjected to combined compression and bizxial bending in this study. The program COL2 has been developed for user-friendly environment using MS-Excel one of the spreadsheets program. The mechanical properties of generic shapes was calculated by Green's theorem.

디자인 및 공예작업에 있어서 래피드 프로토타입에 관한 연구

인치호,정승훈 홍익대학교 산업디자인연구소 2000 미술디자인 논문집 Vol.- No.5

고립성 폐결절의 조직학적 진단에 있어서 경기관지폐생검의 진단적 가치

김치훈,김정주,왕준호,연규민,김형수,리원연,용석중,신계철 건국대학교 의과학연구소 2002 건국의과학학술지 Vol.12 No.-

Transbronchial lung biopsy(TBLB) is a relatively simple and convenient diagnostic tool in solitary pulmonary nodule(SPN) on chest radiograph, which is cannot be diagnosed through routine tests. To investigate the diagnostic value and diagnostic rate of TBLB according to the variable factor, we analyzed 69 patients with radiologically SPN lesion on chest radiograph which was confirmed histologically. A histologic diagnosis of TBLB was made in 47 of 69 patients(68.1%), in which 26 of 37(70.3%) with malignancy and 21 of 32(65.6%) with benign lesion. There were no significant differences in diagnostic yield according to age, sex and location of the lesion. The diagnostic rate tended to increase with the more than 5 pieces to acquired by TBLB. When the size of SPN was less than 3 ㎝, it cannot be diagnosed. In conclusion, TBLB is a diagnostic procedure with good yield and safety, but percutaneous needle aspiration, transbronchial needle aspiration, and bronchial washing fluid cytology may be a complementary procedure to overcome the limitation of TBLB and get higher diagnostic yield for SPN.

忠南地域 屠畜豚의 肺病變으로부터 分離한 Actinobacillus pleuropneumoniae의 生物學的 및 免疫學的 特性

이종훈,장경수,장치훈,김일택,정용성,김귀현,전무형 충남대학교 수의과대학 동물의과학연구소 1996 動物醫科學硏究誌 Vol.4 No.-

An epidemiologic study on pleuropneumonia in the slaughter pigs(Chonan and Asan area, Chungnam province, Korea) during the period of January 1994 through December 1995 was conducted. Isolation of A. pleuropneumoniae was attempted in 425 pigs with pneumonic lesions. Biochemical properties, antimicrobial susceptibility, serotypes and pathogenicity of A. pleuropneumoniae isolates were investigated. In addition, outer membrane protein(OMP) of the isolates were extracted to determine its properties and immunogenicity in both mice and piglets. Of 3,395 slaughter pigs, pleuropneumonia was observed in 425 pigs(10.6%). A. pleuropneumoniae was isolated from 22 pigs(5.2%) out of 425 pigs with pneumonic lesions. The biochemical properties of all isolates were same as those of reference A. pleuropneumoniae strain. Among 22 isolates, 9, 1 and 12 isolates were serovar 2, 3 and 5, respectively. The results of antimicrobial susceptibility test revealed that the isolates showed high susceptibility to ciprofloxacin and cephalothin, moderate susceptibility to amikacin, gentamicin, kanamycin and streptomycin, and low susceptibility to erythromycin, tylosin and sulfadimethoxin. The isolates were varied in pathogenicity to mice. Median lethal dose of LE9402(serovar 2) and LE9511(serovar 5) were 9.2×10^7CFU and 2.8×10^7CFU, respectively. Specific pneumonic lesions were observed from the infected mice with clinical signs. Bacteria recovery rate was high in the lung, but low in heart blood and tracheas. Serovar 2 was found to be more pathogenic than serovar 5 in guinea pig. Mortality on guinea pigs inoculated with serovar 2(5.4×10^8 - 5.4×10^6CFU) abd serovar 5(2.8×10^8 - 2.8×10^6CFU) was 20-40% and 40-80%, respectively. A severe hemorrhagic lesions and focal pneumonic lesions were observed from dead guinea pigs. Bacteria recovery rate was relatively higher in the lung than that of other organs. In the SDS-PAGE analysis, OMP-enriched fractions of both isolates and reference strains contain common peptide bands equivalent to molecular weight of 17, 27, 42, 52 and 95Kd. In addition to common peptide bands, the bands which are specific to each isolate were also observed. The profiles of Sephadex G25 fractions showed 3 major peaks. The common peptide bands which were observed by SDS-PAGE of the crude OMPs were found i the peaks 1 and 2. The OMPs extracted from serovar 2(LE9402) and serovar 5(LE9511) provided high level of protection in mice(70-80%) and pigs(100%). All animals inoculated with OMPs were seroconverted, showing micro-agglutination titer of 640 to 1280.

-G308A Tumor Necrosis Factor-α 유전자 다형성과 주요 우울장애의 연합연구

배치운,오해정,채정호,박원명,전태연,한훈,김광수 大韓神經精神醫學會 2003 신경정신의학 Vol.42 No.2

Objectives : The present study was to examine possible association between the - G308A tumor necrosis factor (TNF)-α gene polymorphism and major depressive disorder (MDD) in Korean. Methods : 108 inpatients with MDD and 125 healthy controls participated in this study. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism. Results : Genotype and allele distributions in patients with MDD (p=0.02, P=0.01, respectively), were significantly different from those of the controls. Conclusion : The present study suggests that the -G308A TNF-α gene polymorphism may have a potential role for the susceptibility to MDD in Korean population.

절수에 의한 Mongolian Gerbil 장기중량변화에 관한 분석연구

김무강,이기훈,이강이,송치원,이경열,권효정,박미선,정승혁,이행연,김명철 충남대학교 수의과대학 동물의과학연구소 2000 動物醫科學硏究誌 Vol.8 No.-

In this study, authors measured the each organ weight of the long term water deprived Mongolian gerbil, after then we calculated the mean, standard deviation, variance coefficient of the real measured organ weight and induced the organ weight change quantity, rate of quantity, deviation between measured and theological organ weight, deviation rate, sum of deviation rate, organ weight change rate, rate of organ weight by the mathematical formula. The results obtained as follow 1. The weight of the brains, lung, and testis were abruptly decreased after water deprived until the 5th day, after then slowly decreased until the 20th day. 2. The weight of the heart was decreased gradually from the first day until the 20th day. 3. The weight of the liver was abruptly decreased until the 10th day, after then the more slowly decreased until the 20th day. 4. The weight of the thymus, spleen, kidney, and pancreas were abruptly decreased until the 15th day, after then increased slowly until 20th day but the weight of the kidney was abruptly increased from the 10th day. 5. The organ weight change rate and the rate of the each day organ weight were very diversified.

톨루엔 디이소시아네이트 폭로 근로자들의 생물학적 모니터링

안연순,노재훈,김치년,박윤정,정상혁 大韓産業醫學會 1995 대한직업환경의학회지 Vol.7 No.2

Toluene diisocyanate(TDI) is widely used in the production of flexible polyurethane foams, as well as in the formulation of polyurethane paints and coatings. The commercial material is generally a mixture of 2,4- and 2, 6-TDI, the predominant mix being 80% 2,4 and 20% 2,6-TDI. The 2,4-isomer is considerably more reactive than the 2,6-TDI at ambient temperatures due to steric factors involving the positions of the isocyanate groups relative to the ring methyl group. Because of this difference in the reactivities of the isomers, it seemed probable that there might be an increase in the amount of 2,6-TDI offgased relative to the 2,4-isomer. Therefore a relative enrichment of the 2,6-TDI has been found in industrial atmospheres. Toluene diamines, which are metabolites of TDI, in urine have a linear relation with exposure to TDI, so that urianry TDA could be used as a biological index of the exposure to TDI. This study was conducted to investigate the distribution of TDI isomer in industrial atmospheres and to propose proper biological monitoring methods by identifying the relationships between the environmental TDI exposure and concentration of TDA in urine. Concentrations of 2, 4-TDI and 2, 6-TDI in air were 4.38㎍/㎥ and 25.43㎍/㎥, respectively. The Threshold Limited Value of 40㎍/㎥ was exceeded for the 2, 6-TDI in about 46.8%(22 samples) of the samples, while the 2, 4-TDI was not at all exceeded. The ratio between 2, 4-TDI and 2, 6-TDI varied in air samples in the range of 2.4%:97.6%-51.0%:49.0%. There was an enrichment of 2, 6-TDI in air relative to the 2, 4-TDI. Concentrations of 2, 4-TDA and 2, 6-TDA in urine were 1.31㎍/g creatinine and 4.16㎍/g creatinine, respectively. The ratio between 2, 4-TDA and 2, 6-TDA varied in urine samples in the range of 1.4%:98.6%-99.9%:0.1%. There was an enrichment of 2, 6-TDA in urine relative to the 2, 4-TDA. No relation between the concerations of TDA isomer in urine and concerations of TDI isomer in air was found. Above results of this study, workers were more exposed to the 2, 6-TDI relative to the 2, 4-TDI in industrial atmospheres. Therefore, the establishment of TLV for 2, 6-TDI should be considered. Also, the further studies on biological monitorigs of workers exposed to TDI should be continued.

Governance Inhibitors in IT Strategy and Management: An Empirical Study of Korean Enterprises

( Jung Hoon Lee ),( Chi Hoon Lee ),( Kap Young Jeong ) 연세대학교 동서문제연구원 2008 Global economic review Vol.37 No.1