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.

Switched Reluctance Motor의 진동, 소음 특성해석에 관한 연구

정태욱,최태완,이태환 진주산업대학교 2000 산업과학기술연구소보 Vol.- No.7

Switched reluctance motor(SRM) drive system is to be compatible for wide range adjustable speed motoring system because it has the same driving characteristics of DC series motor, easy control principle and high efficiency characteristics. By this reason, SRM drive system will be applied to many commercial adjustable speed application that requires economic advantages and high performance abilities. But, SRM drives generate large vibration and acoustic noise because it is rotated by step pulse mmf and switching commutation mechanism. This disadvantage has been obstacles to applicate SRM drives as generalized motor drive system. The main origin of vibration and noise is caused by commutation method which applies step pulse waveform mmf to stator pole and removes the mmf suddenly. This sudden variation of stator flux vibrates stator frame by radial direction and excites natural vibration mode of stator. This paper analyzes the characteristics of vibration and acoustics noise of SRM from the viewpoint of natural mode and driving coidition, and consider the reduction strategy of that.

SRM 의 가변 인덕턴스 산정과 활용

鄭泰旭,李泰煥 진주산업대학교 1999 산업과학기술연구소보 Vol.- No.6

Recently, a Switched Reluctance Motor(SRM) is researched on improvement of control scheme, optimization of magnetic structure, combination of motor and inverter, and reduction of torque ripple vibration, acoustic noise and vibration. Especially, one of the disadvantage of an SRM is the higher torque ripple compared with conventional drive system. In this viewpoint, Fully-pitch SRM has many versatilities, and acoustic noise and torque ripple can be reduced by optimal design of magnetic structure and proper switching controls. Fully-pitch SRM adopts the fully-pitch winding method and develops torque by mutual inductance and self inductance. In order to design motor structure, estimation of inductance and prediction of torque characteristics are indispensable. So this paper suggests the estimation method of inductance using permeance calculation method, and design appropriate magnetic structure which can be reduced torque ripple by using this method.

수입각증후군에 의한 급성 복증 1례

정은욱,지삼룡,이영태,박지훈,김동기,제인수,채두근,박성재,박은택,이연재,이상혁,설상영,정정명 白中央醫療院 2005 仁濟醫學 Vol.26 No.1

Afferent loop syndrome is an uncommon complication of a gastrectomy and Billroth Ⅱ reconstruction. It may cause symtoms at any time from the first postoperative day to many years after the gastrectomy. Afferent loop syndrome is characterized by abdominal pain, vomiting and elevation of serum amylase. Thus, it is difficult to differentiate afferent loop syndrome from other cause of acute pancreatitis. However, the history of gastrectomy can be an important clue for diagnosing afferent loop syndrome. We experienced one case of chronic afferent loop syndrome with acute pancreatitis. After appropriate management, the abdominal pain disappeared and serum amylase level decreased. We report this case with a review of relevant literatures.

정신분열병 환자에서 얼굴 영상의 작동기억 장애 : 기능자기공명영상연구

이창욱,김태석,주라형,박주미,박여진,김종진,전신수,배치운,김정진,이수정,이철,백인호 大韓神經精神醫學會 2005 신경정신의학 Vol.44 No.2

Objectives : Impaired processing of facial information is one of the broad ranges of cognitive deficits seen in patients with Schi-zophrenia. We aimed to elucidate the differences in brain activities involved in the process of facial working memory between schizophrenic patients and healthy comparison subjects. Methods : Twelve patients with schizophrenia were recruited along with twelve demographically matched healthy volunteers as a comparison group. Functional magnetic resonance imaging (fMRI) was used to assess cortical activities during the Perfor-mance of a 2-back working memory paradigm using images of neutral faces as mnemonic content. Rcsults : The patient group performed the tasks with reduced accuracy. Group analysis revealed that the left fusiform gyrus, the right superior frontal gyrus, the bilateral middle frontal gyri/insula, the left middle temporal gyrus, the precuneus, the quadrangular lobules and the vermis of cerebellum showed decreased cortical activities in the patient group. On the other hand, an increased level of activation in the lateral prefrontal cortex and the pahetal lobule was observed from the patient group, all in the right hemisphere. Conulusion : A decreased level of activity in the left fusiform gyrus among the patient group implicates inefficient processing of facial information. An increased level of activation in prefrontal and parietal neural networks from the patient group confirms earlier findings on the impaired working memory of patients with schizophrenia.

그람양성구균에 대한 Teicoplanin과 Vancomycin의 시험관내 항균력

최태열,김경숙,전용관,서일혜,김정욱,이웅수,안정열,김홍석,정재용,최효선,김덕언,유진우 대한감염학회 1994 감염 Vol.26 No.1

An increasing frequency of methicillin resistant S. aureus(MRSA), methicillin resistant coagulase negative staphylococci(MRCNS) and Enterococcal infection have been observed in recent years. Teicoplanin is a new glycopeptide antibiotic obstained from the Actinoplanes teicomycetius. The molecular structure and spectrum of antimicrobial activity of teicoplanin is simillar to those of vancomycin, and has been reported to have an excellent in vitro and in vivo effect against various gram-positive infections. Therefore, we evaluated the in vitor susceptibility of gram positive cocci, such as, S. aureus, coagulase negative Staphylococci(CNS), and Enterococci to teicoplanin and vancomycin. The total 253 strains consisted of MSSA(40), MRSA(53), MSCNS(47), MRCNS(48), and Enterococci(65). They were assayed by disc diffusion and agar dilution. During the study, 57% of S. aureus and 49% of CNS showed resistance to methicillin. The inhibitory diameter of teicoplanin was 15-20mm in MSSA, 12-19mm in MRSA, 13-24mm in MSCNS, 11-23mm in MRCNS, and 15-22mm in Enterococci respectively, and showed sensitivity in all but 8 strains(3.2%). The range of the minimum inhibitory concentration (MIC) of teicoplanin to MSSA, MRSA, MSCNS, MRCNS and Enterococci were 9.12-2.0㎍/ml, 0.25-2.0㎍/ml, & 0.25-32㎍/ml, 0.12-1.0㎍/ml respectively. One case of S. haemolyticus was resistant to teicoplanin (32㎍/ml) by the agar dilution method. Eight minor (3.2%) and one major(0.4%) error was observed when the MIC and disk diffusion data were correlated with teicoplanin. As for vancomycin the inhibitory diameter was 17-21mm in MSSA, 15-21mm in MRSA, 18-26mm in MSCNS, 18-25mm in MRCNS, and 16-22mm in Enterococci respectively. The range of the MIC of vancomycin to MSSA, MRSA, MSCNS, MRCNS, and Enterococci were 0.25-1.0㎍/ml, 0.25-4.0㎍/ml, 0.5-2.0㎍/ml and 0.5-2.0㎍/ml respectively. One minor error (0.4%) was seen with the vancomycin disk. The MIC90 of MSSA and MRSA exhibited the same results in teicoplanin (1.0㎍/ml, 1.0㎍/ml), and vancomycin(2.0㎍/ml, 2.0㎍/ml). MSCNS and MRCNS exhibited greater MIC90 with teicoplanin(4.0㎍/ml, 8.0㎍/ml) than vancomycin(2.0㎍/ml, 2.0㎍/ml). Incontrase Enterococci were more susceptible to teicoplanin(0.5㎍/ml) than to vancomucin (2.0㎍/ml). Results from this analysis indicated that both teicoplanin and vancomycin were very excellent for gram positive infections, especially those resistant to methicillin.

위험평가(Risk Assessment)에 의한 업종별 위험(Risk)의 구분

박동욱,박덕묵,정광수,윤충식,김태형,노영만,이경남,이송권,김현욱 한국산업위생학회 2003 한국산업보건학회지 Vol.13 No.2

A total of 514 workplaces in 17 industries were inbestigated through walk-through survey. These industries were all small companies with less than five workers and didn't have work environmental measurement data. These industries were ranked by risk that was evaluated by combination of toxicity and possibility of exposure to chemical hazardous agents produced at operations of industry. Risk Index(RI) was qualitatively combined by the combination between hazard and potential of exposure to chemical hazardous agents. Industries that were regarded as having the highest risk were wood and products of wood, chemicals and chemical products, basic metals, other vehicles, trailers and semi-trailers, and fumiture manufacturing. These industries were found to have operations with higher risk than other industries. This study found that more attentions should be paid to these industries with that more attentions should be paid to these industries with high risk.

One Arm Curl 동작의 Simulation

조동욱,서국웅,윤양진,김정태,조승제 釜山大學校 附設 體育科學硏究所 1997 體育科學硏究所 論文集 Vol.13 No.-

In recent years, numerical simulation of human body motion has received an increasingly wider range of application. Computer simulations have greatly contributed to the understanding of kinematics and dynamics of human motion. Such simulations are being used in ergonomics to better understand and thus improve the interaction of persons with machines and with workplace configurations. In sports, the simulations are being used to optimize performance, to develop equipment for injury prevention, and to speed and enhance recovery from injury. Then in this study simulated one arm curl motion for understanding force and moment in arm's each joint, and this segment modeling was used 2-dimension, 3-link system. From simulation of mathematica 3.0 we found kinematic and kinetic factors with imaginatively lift of dumbbell and simulated random value of the last curl angle, weight of dumbbell, cycle of motion and so on. The conclusions of this study is as follows ; 1. As this study link system, weight of dumbbell influence not a stance and motion but magnitude of force and moment. 2. The force showed even as smooth curve in all cycle. Moment showed biggist between 0.5sec and 1.5sec. The magnitude order is shoulder, elbow and wrist joint. 3. Motion of system in this study is very similar human arm's motion considering that law of inertia and helped effectively delegation of force. 4. Mathematica is useful language as simulation program. Forward it needs study about modeling and simulation on muscle factors, also human body simulation.

40세 이하 관상동맥 질환자에서 장기적 임상 관찰

이승욱,정명호,박종철,박형욱,조상희,김원,김계훈,이상현,강경태,조장현,김남호,김건형,안영근,조정관,박종춘,강정채 全南大醫大 2001 전남의대학술지 Vol.37 No.2

일부 지역 학동기 아동의 우발사고에 대한 조사

모정욱,심운택,이태용 충남대학교 의과대학 지역사회의학연구소 1991 충남의대잡지 Vol.18 No.2

The purpose of this study was to investigate school children's monthly incidence rates and causes of accident. The number of studied subjects were 279 school children. The results were as follows: 1. Average monthly incidence rate of accident for male was 17.8 per 100 persons, and that of female was 12.7. That of the 6th grade was 32.7, and the 1st grade was 5.6, and March was the highest in incidence rate of studied months. 2. The accidents occured most frequently in the 6th grade and relatively low in the 1st grade. 3. The presence of parents, their occupation, and education and monthly income of household were not affected school children's accident. 4. Time required and distance from house to school were concerned to children's accident. Walking was relatively lower than other way in the way of transport from house to school. 5. The majority sites of injury were legs & arms. 6. Most of injured children treated at the medical institute.