Effects of Pilger Rolling and Heat Treatment on Microstructure and Corrosion Resistance of Ag-electroplated 304 Stainless Steel Tubes

Hyun Park,Woo‑Jin Lee,Jae‑Han Son,Han‑Kyun Shin,Sung‑Kyu Hong,Hyo‑Jong Lee 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.8

We introduce a cost-effective method that combines electroplating with metal cold working processes to manufacture compositetubes with robust corrosion resistance. First, a 3-step electroplating process was developed to form an adhesive anduniform Ag coating on the outer wall of a 304 stainless steel tube. The process consisted of a Ni-strike step for removing thepassivation layer of the initial 304 tube, Cu deposition for smoothing the surface by adding a buffer layer, and Ag deposition. To reinforce the interfacial adhesion between the electroplated layers and the 304 tube and increase the area of the Ag coating,a pilger rolling or pilger rolling + heat-treatment process was performed after the Ag electroplating process. Scanningelectron microscopy of the composite tubes after each process indicated that the as-deposited Ag coating changed fromhaving a rough to smooth surface after only pilger rolling and with additional heat treatment. Electron backscatter diffractionanalysis of the microstructures and textures of the tubes revealed that dynamic recrystallization occurred extensively duringpilger rolling, resulting in the formation of a relatively defect-free grain structure without heat treatment. Furthermore,electrochemical polarization curves determined that the Ag-coated composite tubes are superior to the uncoated 304 tubein terms of corrosion resistance under Cl−atmosphere, owing to the formation of a AgCl passivation layer during testing. Surface analysis of the composite tubes suggests that the properties of the AgCl passivation layer are related to the grainsize of the Ag coating and the density of plastic-deformation-induced defects.

운동실조를 동반하지 않은 급성외안근마비 1례

신대수,이승회,이한샘,박성욱,박현영,장혁,김요식,조광호 圓光大學校 醫科學硏究所 2004 圓光醫科學 Vol.19 No.2

민간투자 사업시행자 선정절차 모델 개발

한현종,황지선,신종현,이찬식 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

Since「the Act on Private Participation in Infrastructure(PPD)」was established in 1998, a number of projects have been procured by private-sector-initiatived system for infrastructure development. However, there are many shortcomings in the procedure of selecting project promoter for the domestic-PPI projects due to deficient regulations, lack of investment appetites, necessary skills and experiences, etc. An improved promoter selection procedure is necessary to select a competent project promoter and to foster participation of the private party. The purpose of this study is to suggest a procedural model for selecting competent project promoter. This model was made by comparing our regulations and procedures with foreign nation's. The suggested model is comprised of PQ, two phased evaluation system for proposals. To manage the overall procedure well, an involvement of professional "project promoter selection team" would be highly recommended.

악성 거대 난소 점액성 종양 1예

신형도,박형진,김홍곤,한원철 圓光大學校 醫科學硏究所 1999 圓光醫科學 Vol.15 No.1

Mucinous tumor are cystic tumors with loculus lined with mucin-secreting epithelium constitute approximately 8-10% of primary epithelial ovarian tumors. Of all mucinous neoplasms, 75-85% are benign. It is often reach very large size particularly with the benign counterpart being reported on occasion to have exceed 100 lbs. Malignancy develops in 5-10% of benign mucinous cysts. About 15-20% of neoplasms are bilateral. We experienced a huge ovarian mucinous tumor of 155 ㎏. measured 42 × 30 × 28 ㎝ in size, and the volume of cystic contents was about 10 L in a nulligravida 36-year-old woman. Pathologic diagnosis was moderately differentiated mucinous cystadenocarcinoma of right ovary. So, we presented with a brief review of literatures.

구리의 전기석출시 젤라틴이 물성에 미치는 영향

신석재,강현춘,안형환,강안수,김용렬,한성만,이한섭 明知大學校 産業技術硏究所 1995 産業技術硏究所論文集 Vol.14 No.-

In the electrodeposition of copper foil for preparing printed circuit boards, a little amount of gelatin as a addition agent has been used for the better characteristics of a coat of electroplating. Gelatin modifies the physical properties such as mechanical strength, matte-side roughness, ultimate tensile strength(U.T.S), and elongation of copper foil, furthermore gelatin have influence on the structure of electrodeposits and the cathode polarization. The electrolyte used was of a composition; CuSO₄·5H₂O 300g/ℓ, H₂SO₄ 100g/ℓ, NaCl 10 ppm as a brightner, and was gelatin 0-7 ppm as a addition agent. Current density was 50 A/dm², and the temperature of electrolytic bath was 50 to 52 ℃. Experiments showed that the optimum gelatin concentration was 5 ppm with the consideration of the numbers of electrodeposited nuclei. And the nuclei numbers was sharply increased under 5 ppm, but was almostly constant above 5ppm. Average matte-side roughness by Surfcorder was gradually increased with the increasing gelatine concentration up to 2 ppm, and maximum roughness was observed at 2ppm. The roughness showed gradual decrease within the concentration range of 2 to 4 ppm, and was almost constant above 4ppm . Within the gelatine concentration range of 0 to 7 ppm, as the concentration increased, UTS was increased and elongation was decreased logarithmically. Also, in comparison between UTS and elongation, gelatin was identified as an addition agent acting inversely.

안면비대칭 환자에서 하악의 측방변위와 두개관형태 사이의 연관성

신상욱,이상한,장현중 大韓顎顔面成形再建外科學會 1996 Maxillofacial Plastic Reconstructive Surgery Vol.18 No.4

This study was intended to perform the relationships between mandibualr lateral deviation in facial asymmetry patients and morphology of the cranial vault. In 30 patients(males 14, female 16) using submento-vertical cephalograms that were taken in the pre-operaticve state and posteroanterioir cephalograms that were taken in centric occlusion before, immediate and long term after surgery. 1. Mean mandibular deviation was about - 3.12°and mean of absolute measurement was about 2.50°on the submento-vertical cephalograms. 2. On the submento-vertical cephalograms, there was no significant difference between non-deviation and deviation side but it had tendency that deviation side was larger than non-deviation side on the frontal portion of cranium(Y10 to Y6) and deviation side was samller than non-deviation on the temporal portion of cranium(Y5, Y-1 to Y-5). 3. Mean mandibular deviation was about 1.40°and mean of absolute measurement was about 3.95°on the posteroanterioir cephalograms. 4. There was statistical significance on the influence of surgical change(PT2A-PT1A) to the relapse(PTLA-PT2A)(p<0.05). The more increasing of the change, the more relapse on the posteroanterioir cephalograms. 5. There was no statistical significance on the influence of degree of mandibular deviation to morphology of the cranium on the submento-vertical cephalograms. But it had tendency that the more mandibular deviation, the larger the non-deviation side on the anterior cranium and deviation side on the posterior cranium(p>0.05). 6. There was statistical significance on the influence of the degree of mandibular deviation on the posteroanterioir cephalograms to the difference between non-deviation and deviation side. The more increasing of mandibular deviation, the larger the non-deviation side on the Y4 to Y-6(p<0.05). 7. There was no statistical significance on the influence of difference between non-deviation and deviation side to the relapse on the posteroanterioir cephalograms. But it had tendency that the more increasing of the differece between non-deviation and deviation side, the more increasing the relapse on temporal of cranium.

오프라인 프로그래밍을 이용한 스카라 로봇의 비쥬얼 피드백 제어

신행봉,이우송,이현철,한성현 한국공작기계학회 2004 한국공작기계학회 춘계학술대회논문집 Vol.2004 No.-

The equipment of industrial robot in manufacturing and assembly lines has rapidly increased. In order to achieve high productivity and flexibility, it becomes very important to develop the visual feedback control system with Off-Line Programming System(OLPS). We can save much efforts and time in adjusting robots to newly defined workcells by using OLPS. A proposed visual calibration scheme is based on position-based visual feedback. The calibration program firstly generates predicted images of objects in an assumed end-effector position. The process to generate predicted images consists of projection to screen-coordinates, visible range test, and construction of simple silhouette figures. Then, camera images acquired are compared with predicted ones for updating position and orientation data. Computation of error is very simple because the scheme is based on perspective projection, which can be also expanded to experimental results. Computation time can be extremely reduced because the proposed method does not require the precise calculation of tree-dimensional object data and image Jacobian.

경영자보상구조에 관한 실증연구

신현한,이만용,장진호 연세대학교 경영연구소 2003 연세경영연구 Vol.40 No.1

본 연구는 2001~2002년 거래소와 코스닥에 상장 및 등록되어 있는 기업을 표본으로 하여 현금성과급에 영향을 주는 요인을 분석하고, 현금성과급과 주식성과급 간의 관계를 살펴보았다. 연구결과 첫째, 동일 산업에 속한 비교회사와의 상대적 성과평가(relative performance)에 근거하여 경영자보상이 결정됨을 발견하였다. 둘째, 스톡욥션을 부여한 기업의 경우, 회계적 성과측정치와 경영자보상간의 민감도가 낮음을 발견하였다. 이 결과는 회계적 경영성과 측정치가 경영자의 성과를 측정하는데 적합성이 떨어지는 경우, 기업은 주식수익률에 의한 스톡옵션 인센티브제도를 도입하여 회계적성과측정치에 근거한 현금보상을 보완한다고 해석된다. 셋째, 임원의 현금보상이 높은 기업들에서 스톡옵션이 도입될 확률이 높음을 발견하였다. 이는 기업들이 현금성과급에 의한 유인제도뿐만 아니라 스톱옵션 인센티브제도를 함께 사용하고 있음을 의미한다.

고혈압 환자에서 Leukoaraiosis 정도와 망막증과의 연관성 : 예비연구 Preliminary Results

신동익,한현정,서대희,이광훈 關東大學校 醫科大學 醫科學硏究所 2002 關東醫大學術誌 Vol.6 No.1

Changes in the cerebral white matter (leukoaraiosis;LA) are detected with increasing frequency by computed tomography (CT) and magnetic resonance imaging (MRI) in elderly patients with diabetes mellitus and hypertension. The purpose of this study is to determine whether the severity of retinopathy is correlated with degree of LA in patients with hypertension. Twenty-three consecutive patients with patients with hypertension admitted in the department of neurology were evaluated for degree of LA and severity of retinopathy. 8patients were 15female. The age distribution was between 52 and 85 years(mean 69.1years). The duration of hypertension was between 1 and 30 years(mean8.2 years). The degree of LA was correlated with severity of hypertensive retinopathy(p<0.05), especially in relatively young patient, short periods of disease, and female paitents(p<0.05). We can make a rough estimation of degree of LA with fundus examination without CT or MRI evaluations in hypertensive patients, especially in relatively young and female patients with short durations of disease. However, more broad study should be made for these value and relationship.

석면함유 슬레이트 지붕 물받이 퇴적물 중 석면 섬유 함유율

임지현,한솔민,김현석,신유민,박시은,허정윤,김민영,장봉기 순천향대학교 기초과학연구소 2022 순천향자연과학연구 논문집 Vol.28 No.1,2

This study attempted to determine the degree of asbestos release from the aging slate roof by comparing the asbestos content in the slate roof rain gutter with a colored steel plate (tin plate) over the slate roof. Four slate roof houses located in Haengmok-ri, Asan-si, Chungcheongnam-do, and one house constructed with a colored steel plate on the slate roof were selected to collect the sediment of the roof rain gutter. The asbestos fiber content was calculated by a point counting method using a polarization microscope after pretreatment with conversion treatment and hydrochloric acid treatment. The average asbestos content of the four slate roof rain gutter were 1.89%. However, asbestos was not detected in the Slate covering roof rain gutter, which were constructed on the slate roof. Asbestos fiber content was the highest at 2.89% in the slate roof rain gutter installed in 1976, followed by 2.44% in 1953. From the above results, it is necessary to minimize secondary damage as asbestos fibers released from slate roof houses to the surrounding atmosphere or leaked from slate roofs as rainwater may cause soil pollution and seriously affect residents' health. Although covering with colored steel plates (tin plates) has been shown to prevent the leakage of asbestos fibers to some extent, it is believed that a policy alternative to remove the slate roof as soon as possible is needed to solve the fundamental problem.