미소원공결함을 갖는 자동차 전륜구동 축재의 피로수명 예측

이동길,오환교,정재강 朝鮮大學校 機械技術硏究所 1998 機械技術硏究 Vol.1 No.1

본 연구에서는 현재 생산되고 있는 자동차의 전륜 구동축재료 S43C와 S50C를 대상으로 회전굽힘피로시험을 통해 고주파열처리와 온도조건에 따른 피로크랙 전파거동을 고찰하고, Nisitani가 제안한 역학적 변수에 의해 재료상수를 구한 후 그 적용성을 검토해 보았다. 비열처리재 S43C 및 S50C의 피로한도는 각각 98.1MPa, 107.9MPa이었으며, 열처리재는 각각 147.1MPa, 156.9MPa로서 열처리 후 두 재료 모두 피로한도가 약 49MPa씩 증가하였으며, 저온(-30℃)에서의 피로수명은 상온(25℃)에서보다 두 재료 모두 비열처리재는 약 110%, 열처리재는 약 120% 증가하였다. 또한 본 재료에 실험으로부터 얻어진 재료상수를 Nisitani의 피로크랙전파속도 예측식에 적용하여 피로수명을 예측한 결과 고주파 열처리 여부와 실험온도 조건에 관계없이 약 5% 내외의 낮은 오차를 보이며 잘 일치함을 알았다. In this study, the rotary bending fatigue test was carried out with two kinds of materials, S43C and S50C, using in the front engine and front drive shaft of vehicle. The specimens were heat-treated by high frequency induction method and tested at +25℃ and -30℃ in order to look over the influence of the heat treatment and the temperatures. The mechanical factor, C(2a)p, proposed by Nisitani was employed in the present study to compare the results of fatigue life obtained from experiment and prediction. The fatigue limit of the as-received specimens S43C and S50C were 98.1MPa and 107.7MPa, and that of the heat-treated S43C and S50C were shown 147.1MPa and 156.9MPa respectably. It means that the fatigue limit was increased about 49MPa by high frequency heat treatment. Fatigue lifes of the specimens tested at low temperature(-30℃) showed about 110% for as-received, 120% for heat-treated higher than at room temperature(25℃). It was found the crack length at onset or final fracture tested at low temperature was shorter than the crack length at room temperature(+25℃). The fatigue lifes were predicted with an equation of the fatigue crack propagation proposed by Nisitani, d(da/dN)=C(2a)p, the results were found to be within 5.0% error by comparison with experimented results.

제주공항 항공등화 제어시스템의 고효율 운전대책

이길수,김일환 제주대학교 산업기술연구소 2000 尖端技術硏究所論文集 Vol.11 No.2

This paper presents the new control method of aeronautical ground lighting control system at Jeju airport. In the computer simulation. it is shown how to make a design for high efficiency aeronautical ground lighting control system using PWM inverter and active power filter with PI control. To verify the theoretical analysis, the conventional aero lighting control system using SCR and the proposed control system are built. Results of computer simulation are presented to support discussion.

제주공항 항공등화 제어시스템의 고효율 운전대책

이길수,김일환 濟州大學校 産業技術硏究所 2000 산업기술연구소논문집 Vol.11 No.2

This paper presents the new control method of aeronautical ground lighting conrol system at Jeju airport. In the computer simulation. it is shown how to make a design for high efficiency aeronautical ground lighting control system using PWM inverter and active power filter with PI control. To verify the theoretical analysis. the conventional aero lighting control system using SCR and the proposed control system are built. Results of computer simulation are presented to support discussion.

성인의 천미추부 종괴

조길환,이백권,장도명,김영진,안상태 大韓成形外科學會 1999 Archives of Plastic Surgery Vol.26 No.3

We developed an animal model to recreate the condition of an open fracture in communication with the maxillary sinus. We then studied wound healing of the sinus wall structures following fracture in the presence of autogenous bone and alloplastic implant. This model is designed to simulate the repair of an orbital floor fracture in humans. The New Zealand White rabbit was used as the animal model. Standardized 8mm defects were made bilaterally in the maxillary sinuses to include bone and mucosa in 36 rabbits. Two different implants and autogenous calvarial bone graft were placed in the soft-tissue pockets to obturate the defects, exposing one surface of the implant to the open sinus. Medpor porous polyethylene, silicone and calvarial bone implant were compared. Animals were killed at 1, 2 and 8 weeks after implantation. Gross examination of the specimens for the amount of mucosal closure and implant tissue fixation was performed. Histological sections were evaluated for bone and soft-tissue morphology juxtaposed to the implant. Complete closure of the mucosal defect was demonstrated with each type of implant. Medpor implants showed both vascular and soft-tissue ingrowth into pores by week 1. Bone ingrowth was seen by week 2. Closure of the Medpor obturated defects occurred more rapidly than in the silicone group. The Medpor implants and calvarial bone demonstrated bone and soft-tissue fixation, callus formation and maturation, while mature overlying mucosa was reconstituted over the defects. Silicone implants demonstrated a fibrous tissue reaction within 1 week of implantation and they never became fixed to bone or soft tissue. Maxillary sinus wall regeneration occurred in all defects. This study supports clinical observations of maxillary sinus wall regeneration in humans. Although sacrococcygeal mass is rare and usually found in infants or children, adolescent or adult patients with protruding mass in sacrococcygeal region occasionally come to us simply for a cosmetic problem. In this situation, even though there is no definite neurological deficit, it should be evaluated whether or not the underlying bony pathology or dural defect exists. Few cases about the sacrococcygeal mass have been reported in adults. We reviewed our cases including preoperative evaluation methods and postoperative diagnosis. From March, 1993 to February, 1997, we experienced 6 adult patients with sacrococcygeal mass and no neurological abnormality. Preoperative evaluation were made by plain X-ray, myelogram, computed tomography(CT), and magnetic resonance imaging (MRI), as needed. Postoperative diagnoses were 2 meningoceles, 2 lipomyelomeningoceles, 1 desmoid tumor, and 1 teratoma. From our experiences, CT or MRI is essential to evaluate the sacrococcygeal mass preoperatively. These methods can visualize the precise anatomic location and extent of the mass, its relation to the spinal cord, and associated bony abnormalities. MRI is superior to CT, especially in defining the nature of the mass and involvement of the spinal cord. Conclusively, even a simple mass in the sacrococcygeal region in adults needs MRI or CT evaluation, and MRI is the most valuable method of evaluating the mass preoperatively and provides important information to establish a treatment plan.

원형관로내 층류 맥동유동의 속도와 압력 분포에 관한 연구

박길문,유영태,위광환,이충주,정지철 조선대학교 생산기술연구소 1996 生産技術硏究 Vol.18 No.2

In this study basic equations for the pulsatile laminar flow in a circular rigid pipe containing a slightly compressible fluid are derived and analytical solutions for the distributions of wave propagation factor K, cross-sectional mean velocity u_(m) and pressure P are schematically developed and confirmed experimentally. The pulsatile flow with 0 ≤ f ≤ 48Hz and 0 ≤ Re ≤ 2500 generated by summing the oscillatory flow made by ball valve into steady one. The wave form of pulsatile flow is described as a longitudinal wave and particle velocities measured experimentally are group velocities of the wave packet which are always smaller than phase velocities which are approximate to the sonic velocity C when the radial dispersion and wall friction are negligible. Therefore wave number is approximated to k = ω/c for high angular velocity region. The axial pressures and centerline velocities were measured by strain-gage type pressure transducers and Pito-static tubes, respectively. The cross-sectional mean velocities calculated from centerline velocities with the parabolic distributions of the laminar flow and confirmed by using the ultrasonic flowmeter. We knew that axial distributions of oscillatory velocity and pressure coincide with thoeretical and depend on the Reynolds number and angular velocity.

固眞飮子가 galactosamine으로 유발한 흰쥐의 간중독에 미치는 영향

원철환,정승현,임성우,신길조,윤상협,이원철 동국대학교 한의학연구소 1997 東國韓醫學硏究所論文集 Vol.6 No.1

최근 간질환에 대한 진단과 기술의 비약적인 발전에도 불구하고 치료방법론에서는 그 해결이 모호한 상태에 있다. 실험적으로 간중독을 유발시킨 동물에 약물을 투여하여 그 약화를 입증하려는 노력이 진행되고 있다. 이에 저자는 固眞飮子가 간독성의 완화효과에 미치는 영향을 관찰하기 위하여 固眞飮子추출물을 투여한 흰쥐에 galactosamine으로 간독성을 유발하고 간조직내 glutathione과 과산화지질의 함량, 혈청중의 GOT, GPT, γ-GPT, ALT, LDH의 효소활성측정 및 혈청중의 bile acid함량을 측정하여 다음과 같은 유의한 결과를 얻었다. glutathione의 함량은 固眞飮子을 전처치한 실험군에서 유의성 있게 증가하여고, 과산화지질, 혈청중 GOT, GPT, γ-GPT, ALT, LDH, bile acid는 고진음자를 전처치한 실험군에서 유의성있게 감소하였다. The purpose of this study is to observe the protective effect of Kojinyumja on serum reaction and hepatic tissue in galactosamine treated rats. In this study, the experimental rats divided four group(Normal group, Control group, Sample A group, and Sample B group): Under the same condition, normal and contro1 group were administered water, sample A, B group were administered Kojinyumja for 8days. And then, Coth control group and Sample B group were injected to abdomen with galactosamine for 1day. The rates of glutathione, lipid peroxide, GOT, GPT, γ-GTP, ALP, LDH, and contents of bile acid level were measured. The results are as follows: The glutathione rate significantly increased in sample group, the others(lipid peroxide, G0T, GPT, γ-GTP, ALP, LDH, bile acid) significantly decreased in sample group.

무갑상선 쥐에서 중식성 반흔의 새로운 실험모델

김영진,이백권,장도명,조길환,임풍 大韓成形外科學會 1999 Archives of Plastic Surgery Vol.26 No.4

Proliferative scarring in the form of keloids and hypertrophic scars continues to be a clinical problem for some patients. The lack of an animal model for such scarring has been an obstacle to studying the biology and effective therapy of these entities. Consequently we created an accurate reproductive animal model to systematically study them. Human proliferative scars were explanted into flaps based on isolated vascular pedicles in congenitally rats. We compared the procollagen type Ⅲ peptide levels of proliferative scar tissue before and after explanting. The procollagen type Ⅲ peptide levels of explanted proliferative scar tissue remained increased as before explanting. Histological analysis of the explanted proliferative scar tissue revealed that all explants retained their original histotypic character even after 1 year. We could also retain the volume of implanted proliferative scar for 1 year and studied in vitro cellular proliferation. Fibroblast cultures from explanted scars demonstrated less aggressive growth characteristic than those from original surgical specimens. The advantages of this animal model are as follows: 1. The explants retain their histotypical character for a long period. 2. Placement of the explants outside the dorsum of a nude rat makes serial observation and measurement easier. 3. Agents under test can be injected into the explants through a catheter inserted into a single pedicle of island flap without the possibility of spreading systematically.

전단보강근량에 따른 초고강도 콘크리트를 사용한 고층형 내력벽의 이력거동

윤현도,연길환,정수영,윤석천,이창갑 忠南大學校 産業技術硏究所 1995 산업기술연구논문집 Vol.10 No.1

Three one fourth scale models using ultra high-strength concrete(f' =704 kg/㎠) are tested under the combined action of a constant axial and a horizontal load cyclically to failure. Such specimens are considered to represent the critical 3-story of low part in 60-story tall building of a structural wall system in area of high seismicity. The amount of vertical reinforcement and the level of applied axial stress are identical for the three wall tested. The cross-section of all walls is barbell shape. The aspect ratio(h /l ) of test specimen is 1.8. The primary objectives of this paper are to investigate the influence of the amount of horizontal reinforcement on the lateral resistance, failure mechanism, ductility and energy-dissipation capability of walls with ultra high-strength concrete. In contrast to what is widely believed, the horizontal web reinforcement does not appear to have a significant effect on shear capacity. Certainly, since the reduction of the web horizontal reinforcement to almost half the value specified by building codes doesn't affect the failure load, this effect in not accounted for by the truss analogy concept. The results obtained have helped to identify the causes of wall failure and have demonstrated that the concepts underlying current ACI Building Code provisions for the design of walls conflict with the observed structural behavior. It has been found that shear resistance is associated with triaxial compressive stress conditions that develop in the compressive zone of the section at the base of the wall.

음낭외상시 초음파 촬영술의 유용성

김형지,진정환,이해원,이길호 대한응급의학회 2000 대한응급의학회지 Vol.11 No.3

Background: Testicular rupture is a surgical emergency which command immediate repair. If surgery is delayd, a hematoma causes severe pain and loss of spermatogenesis as well as hormonal functions. Scrotal ultrasonography has been helpful in early diagnosis of testicular rupture. But disadvantage of ultrasonography include a relatively low signal-to-noise level, tissue nonspecificity, lack of contrast media, a small field of view, and dependence on the operators skill and the patients physique. Also the diagnostic accuracy, sensitivity or specificity of scrotal ultrasonography was variable in regard to authors. And so, a diagnostic accuracy of scrotal ultrasonography was evaluated in scrotal trauma. Methods·. We reviewed 38 patients of scrotal trauma from May, 1994 to March, 1998. 6 patients were treated conservatively fellowing sonography and 10 patients treated only surgical exploration without ultasonography Surgical exploration was performed in 22 case, which were evaluated by ultasound before surgical treatment. In a such 22 cases, diagnostic accuracy of scrotal ultasonography was evaluated. Results: We compared ultrasound before treatment with surgical exploration finding in a such 22 cases. The ultrasonographic features in 7(31.8%) out of 22 cases, which showed testicular ruptured, but surgical exploration revealed testicular rupture in5 and epididymal rupture in 1, simple hematocele in 1. In 15(68.2%) out of 22cases the simple hematocele was diagnosed by ultrasonography, but surgical finding feature in of the 7 cases revealed testicular rupture, epididymal rupture in 1, simple hematocele in 7. The sensitivity and specificity for the ultrasonography are 42.9% and 87.5%, and the positive and negative predictive values are 86.5%and 46.7%, respectively. Ultrasonography is low sensitive in identifying testicular rupture. Conclusion: 7trasonography include a relatively low signal-to-noise level, tissue nonspecificity, lack of contrast media, a small field of view, and dependence on the operators skill and the patients physique. Therefore, early surgical exploration for saving the testis should be performed that sonographically by seeing hypoehoic peripheral lesions and disappearance of normal ovoid form of testis, hematocele in scrotal sac.

정신분열병과 N-Methyl-D-Aspartate 수용체 유전자와 연관된 VNTR 표지자인 D9S158 다형성의 연합

김종원,채영규,정은기,김길숙,박강규,이영호,최인근,양병환,한진희 大韓神經精神醫學會 1998 신경정신의학 Vol.37 No.5

정신분열병과 NMDA 수용체와 연관된 D9S158 유전적 표지자와의 연관성을 알아보기 위해 75명의 정신분열병 환자군과 87명의 정상대조군을 대상으로 중합효소연쇄반응을 이용하여 연합연구를 시행하여 다음과 같은 결론을 얻었다. D9S158 유전좌위에는 모두 8개의 대립유전자가 있었고, 각 대립유전자는 cytosine-adenine염기가 반복되는 217염기쌍에서 233염기쌍의 형태였다. 먼저 정신분열병 환자와 정상대조군의 대립유전자의 빈도를 비교해 본 결과 통계적으로 유의한 차이를 보이지 않았다(p〉.05). 환자군을 좀 더 동질적으로 만들기 위해 정신분열병의 가족력 유무, 음성 및 양성증상, 연성신경학적 징후, DSM-IV 임상아형에 따라 환자군을 나누어 대립유전자의 빈도를 비교해 본 결과, 특정 임상양상과 관련이 있는 대립유전자를 발견하지 못하였다. 결론적으로 본 연구에서는 D9S158 유전좌위와 정신분열병의 연관성을 입증하지 못하였으나 NMDA 수용체 유전자주위의 다른 표지자나 좀 더 유전적으로 동질한 환자군을 대상으로 한 추후연구가 필요할 것으로 생각된다. An association study with Korean schizophrenic patients(N=75) and normal controls(N=87) was performed to find the relationship between D9S158 polymorphism and schizophrenia using polymerase chain reaction. Eight different alleles of a dinucleotide polymorphism on D9S158 locus were observed in both group. When we compared the frequencies of alleles between schizophrenics and normal controls, there was no significant difference between two groups. To increase homogeneity of schizophrenic group, we divided schizophrenic group by clinical phenotypes such as family history, negative and positive symptoms(PANSS), soft neurologic signs(NES-K) and DSM-IV diagnostic subtypes. Then we compared the frequencies of alleles among subgroups of clinical phenotypes, and there were no significant differences between subgroups(p〉.05). Although our findings fail to provide an evidence of association between schizophrenia and D9S158 locus, further investigation of other loci that are linked to NMDA receptor gene may be needed in genetically homogeneous subgroups of schizophrenia.