신경회로망에 의한 용접 결함 종류의 정량적인 자동인식 시스템 개발에 관한 연구

김재열,김영석,김병현,유신,김훈조,정진홍 한국공작기계학회 1997 한국생산제조학회지 Vol.6 No.1

A neural network approach has been developed to determine the depth of a surface breaking crack in a steel plate from ultrasonic backscattering data. The network is trained by the use of feedforward three-layered network together with a back-scattering algorithm for error correction. The signal used for crack insonification is a mode converted 70˚ transverse wave. A numerical analysis of back scattered field is carried out based on elastic wave theory, by the use of the boundary element method. The numerical data are calibrated by comparison with experimental data. The numerical analysis provides synthetic data for the training of the network. The training data have been calculated for cracks with specified increments of the crack depth. The performance of the network has been tested on other synthetic data and experimental data which are different form the training data.

남자 고등학교 세팍타크로 경기의 공격기술에 관한 분석 연구

김영호,고문석,제임스전,이영익,차정훈,현종건,김범수,임종만,이석인 한국스포츠리서치 2004 한국 스포츠 리서치 Vol.15 No.6

This research aims at analysis of attack technique in sepaktakraw games. For this purpose, 3 high school coaches observed and recorded each game Five times in videos of high school male players' thirty games in 2003. The conclusion from the analysis of the recorded data are as follows. 1. Scissors spike was the most popular (favorite) attack technique. Rolling spike, tapping spike and heading spike was popular in order. 2. Heading spike showed the highest success rate (73.5%) in attack technique. And tapping spike (69.5%), scissors spike (57.8%) and rolling spike (67.11) showed a lower success rate in order. In failure rate, heading spike (5.5%), tapping spike (36.5%), scissors spike (32.2%) and rolling spike (32.9%) had a higher percentage in order. 3. When receive was stable, the success rate in attach technique was 47.1%, the failure rate was 20.1%. On the other hand, when receive was unstable, the success rate in attach technique was 16.5%, the failure rate was 14.3%.

HMG-CoA 환원효소 억제제에 의한 ICAM-1 유전자의 발현조절

김현진,정효균,홍우정,김군순,조영석,김도희,채수흥,구본정,송민호,노흥규,김영건 충남대학교 의과대학 지역사회의학연구소 2001 충남의대잡지 Vol.28 No.1

Background : ICAM-1 act as one of major adhesion molecules in the atherosclerotic lesion. ICAM-1 expression is mainly regulated at the level of transcription and depend on IFN-γ signal transduction pathway in which the STAT1 transcrption factor is a critical intermediate. IFN-γreceptor not only initiates tyrosine 701 phosphorylation of STAT1 by Jak1 and Jak2, but also phosphorylates serine 727 through the activation of Raf-1/MAP kinases. HMG-CoA reductase inhibitors have anti-atherosclertic effects, beyond normalization of hypercholesterolemia, by directly acting on endothelial cells, macrophages and vascular smooth muscle cells. HMG-CoA reductase inhibitors suppress the synthesis of isoprenoid intermediates such as geranylgeranyl-pyrophosphate or farnesylpyrophosphate. These effects results inhibitors suppress the synthesis of isoprenoid intermediates such as geranylgeranyl-pyrophosphate or farnesylpyrophosphate. These effects results inhibition posttranslational farnesylation and geranyl-geranylation processing of small GTP-binding preoteins and inhibition of normal signaling activities. Method : We made several 5'-deletion constructs of rat ICAM-1 promoter and analyzed the promoter activities by measuring the luciferase activity after transfection into ECV304 cells and smooth muscle cells. We checked the level of total and phosphorylated STAT1 protein by immunoblot analysis using specific antibodies. Results : Lovastatin inhibits IFN-γ-induced ICAM-1 gene expression in the ECV304cell. The cells pretreated with PD98059, MEKK inhibitor showed significantly low ICAM-1 RNA induction with IFN-γ stimulatio. IFN-γ induced phosphorylation of tyrosine 701 was not significantly changed by the pretreatment of lovastatin. But lovastatin suppresses IFN-γ-induced phosphorylation of ERK1/ERK2 which are responsible for the seine 727 phosphorylation in STAT1. Conclusion : We showed that HMG-CoA reductase inhibitors, lovastatin, suppresses IFN-γ mediated ICAM-1 gene expression through the inhibition of transcription. HMG-CoA reductase inhibitor suppresses IFN-γ-induced phosphorylation of serine 727 in STAT1 through the modulation of MAP kinases.

Students’ Perspectives on Pre-recorded Video Lectures Versus Video-Conferencing Lectures in the Untact Era

Kim,Hea-Suk,Cha,Yoonjung,Kim,Na-Young 이화여자대학교 교과교육연구소 2021 교과교육학연구 Vol.25 No.2

The purpose of this study is to examine students’ perspectives on two online learning formats: pre-recorded video lectures versus video-conferencing. There were 90 participants who took College English courses in a university in Seoul. Participants took TOEIC tests before taking the classes and were divided into two different proficiency level groups: a high-level group and a low-level group. All participants studied English via both pre-recorded video lectures and video-conferencing (Zoom) for the whole semester. Questionnaires were carried out to explore students’ perspectives on both online formats in accordance with their proficiency levels. The findings of the closed-ended questionnaires revealed that significant differences were not found between the low- and high-level groups regardless of the online learning formats. Regarding students’ perspectives about these online English formats, a statistical difference was not found between the two groups. It is worth noting that students did not show any significantly different perspectives concerning online courses regardless of their proficiency levels. As for the open-ended questionnaires, both groups noted various benefits and drawbacks of the current online learning platforms. Also, they provided constructive suggestions for these online learning formats. The results of this study have pedagogical implications for carrying out successful online courses.

생체분해성 망막압정을 이용한 망막고정에 대한 실험적 연구

김용백,민병무,김창식,박근성,김승영,길숙종,조항진,이성복,노승무,송규상,강대영,조준식,양준묵,정경수,최선웅,이진호,김학용,인현빈 충남대학교 의과대학 지역사회의학연구소 1998 충남의대잡지 Vol.25 No.1

Biodegradable retinal fixation devices obtain mechnical fixation of the retina with desirable chorioretinal scarring and with the potential for local, sustained release of antimetabolites and steroids to inhibit proliferative vitreoretinopathy. We manufactured a biodegradable retinal tack with barb that was designed in order to prevent intrusion from implantation of retinal tacks. This study was carried to evaluate the efficacy for retinal fixation and the capability for sustained release of drugs with a newly designed biodegradable retinal tack Biodegradable retinal tacks were made of polymers of glycolic acids and were designed with barbs in a shape to prevent the disinsertion. Biodegradale retinal tacks are divided into 3 parts, a conical portion that is inserted into the sclera, a cylinder portion that remains in the vitreous, and a neck portion between the pin and the cylinder. The tapered conical end was manufactured to allow easy insertion through the retina and choroid into the sclera. A cylinder portion was manufactured with a tapered angle that fixes firmly into the orifice of 19 gauge spinal needle. A neck portion, 0.4 mm in diameter, was designed to prevent disinsertion from following implantation of retinal tack. The applicator was a 19 gauge spinal needle and its orifice was prepared to 15°angle to accept the tapered cylinder portion of the retinal tack. The retinal tacks, secured in the needles, were passed through the formed vitreous and inserted into the retina, choroid, and sclera and were released by pushing the internal needle, usually within 2-3mm of the medullary ray of the posterior rabbit retina A retinal tack was placed in each of 8 pigmented rabbit eyes. Slit-lamp biomicroscopy, indirect ophthalmoscopy and fundus photography were performed periodically from 1 day to 8 weeks after surgery. Eight eyes were enucleated and studied by light microscopy at 8 weeks. Biomicroscopic evaluation of the animals revealed edemas adjacent to the retinal surfaces immediately after insertion of the biodegradable retinal tacks in all the animals. These edemas disappeared after 1 week. The first noticeable change in the size of retinal tacks was shown after 2weeks. The size of the retinal tacks gradually got smaller, decreasing to about one-half at 4 weeks and about one-third at 8 weeks. All retinal tacks remained in inserted places without any movement for an 8 week period. On light microscopy, epiretinal proliferations were seen to extend into the vitreous cavity. Cellular capsules that lined the inner aspect of the scleral defect caused by tack insertion were found. However the adjacent retina had a normal cytologic appearance and architecture in all specimens. We manufactured a biodegradable retinal tack that is designed to prevent intrusion from implantation of retinal tacks. All biodegradable retinal tacks reduce in size with time, but no retinal tacks extruded from the inserted place. The newly designed biodegradable retinal tack can be used for retinal fixation and may be used as a vehicle for the introduction of pharmacologic agents to prevent the cellular events that promote proliferative vitreoretinopathy.

노치 형상 및 냉각속도에 따른 Zr-2.5Nb 압력관의 DHC거동

김상재,김영석,임경수,김성수,정용무 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.1

The objective of this study is to investigate the delayed hydride cracking (DHC) velocity and the incubation time for the water-quenched and furnace-cooled Zr-2.5Nb tube with the different radius of a notch tip. DHC tests were carried out at constant K_1 of 20 MPa√m and 250℃ on the cantilever beam (CB) specimens subjected to furnace cooling or water quenching after electrolytic charging with 57 or 72 ppm hydrogen, respectively. An acoustic emission sensor was attached to the CB specimens to detect the incubation time before the start of DHC. The shape of the notch tip changed from the fatigue crack to the dull crack with its radius ranging from 0.1 to 0.15 mm. The DHC incubation time increased remarkably with the increasing radius of the notch tip, which appeared more strikingly on the furnace-cooled CB specimens than on the water-quenched ones. However, both furnace-cooled and water-quenched CB specimens indicated little change in the DHC velocity with the radius of the notch tip unless their notch tip exceeded 0.125mm. These results demonstrate that the uncleation rate of hydrides at the notch tip determines the incubation time and the DHC velocity becomes constant after the concentration of hydrogen at the notch tip reaches the terminal solid solubility for dissolution (TSSD). This observation agrees well with Kim's DHC model. A difference in the incubation time and the DHC velocity between the furnace-cooled and water-quenched specimens is discussed in terms of the uncleation rate of hydrides at the notch tip and the hysteresis of hydrogen solubility.

Delayed Hydride Crack Velocity of Zirconium Alloys with the Direction of an Approach to Temperature

KIM, Young Suk,KIM, Kang Soo,CHEONG, Yong Moo Atomic Energy Society of Japan 2006 Journal of nuclear science and technology Vol.43 No.9

<P>The delayed hydride cracking (DHC) tests were conducted on Zr-2.5Nb compact tension specimens with the test temperatures reached by a heating and a cooling. The Zr-2.5Nb specimens were either furnace-cooled or water-quenched after a hydrogen charging treatment to contain 10 to 100 ppm H. On an approach to the test temperatures by a cooling, both the Zr-2.5Nb specimens showed the DHC velocity increasing with an increasing temperature over a temperature range of 100–300°C, irrespective of the cooling rate. However, on an approach to the test temperatures by heating, the furnace-cooled Zr-2.5Nb showed a DHC arrest at temperatures over 180°C and no DHC at 250°C, and the water-quenched ones did have a DHC growth, even at 250°C. Using Kim’s DHC model we elucidate the DHC arrest in the furnace-cooled Zr-2.5Nb at temperatures over 180°C and the DHC growth in the water-quenched specimen, even at 250°C, upon an approach by a heating.</P>

Direct effectiveness of pneumococcal polysaccharide vaccine against invasive pneumococcal disease and non-bacteremic pneumococcal pneumonia in elderly population in the era of pneumococcal conjugate vaccine: A case-control study

Kim, Jong Hun,Chun, Byung Chul,Song, Joon Young,Kim, Hyo Youl,Bae, In-Gyu,Kim, Dong-Min,Choi, Young Hwa,Jun, Yoon Hee,Choi, Won Suk,Kang, Seong Hee,Kwon, Hyun Hee,Jeong, Hye Won,Kee, Sae Yoon,Hur, Jia Elsevier Ltd. 2019 Vaccine Vol. No.

<P><B>Abstract</B></P> <P><B>Background</B></P> <P>While herd effects and serotype replacement by childhood pneumococcal protein conjugated vaccines (PCVs) continues to accumulate worldwide, direct effectiveness of 23-valent pneumococcal polysaccharide vaccine (PPV23) against pneumococcal diseases in the elderly has been challenged. We estimated the direct effectiveness of PPV23 in the elderly population.</P> <P><B>Methods</B></P> <P>For a hospital-based case-control study, cases of invasive pneumococcal disease (IPD) and non-bacteremic pneumococcal pneumonia (NBPP) (adults ≥ 65 years) were identified in 14 hospitals participated in the pneumococcal surveillance program from March 2013 to October 2015, following implementation of PPV23 national immunization program (NIP) for the elderly in the Republic of Korea. Controls matched by age, sex, and hospital were selected at ratios of 1:2 (IPD) or 1:1 (NBPP). Clinical data and vaccination records were collected. Vaccine effectiveness was calculated as (1-adjusted odds ratio) × 100.</P> <P><B>Results</B></P> <P>We enrolled 148 IPD and 557 NBPP cases, and 295 IPD and 557 NBPP controls for analyses. Overall effectiveness of PPV23 against IPD was 28.5% [95% confidence interval (CI) −5.8%–51.6%] and against NBPP was 10.2% (-15.1-30.6) in all patients ≥ 65 years. However, in subgroup analysis of patients aged 65–74 years, PPV23 was protective against IPD [effectiveness 57.4% (19.4–77.5)] and against NBPP [effectiveness 35.0% (2.3–56.7)]. Furthermore, serotype-specific effectiveness of PPV23 against IPD was 90.6% (27.6–98.8) for PPV23-unique serotypes and 81.3% (38.6–94.3) for PPV23 serotypes excluding serotype 3.</P> <P><B>Conclusions</B></P> <P>This study indicates that PPV23 with broad serotype coverage might be beneficial in preventing IPD and NBPP due to non-PCV13 serotypes in the young-elderly, with potentially increasing effectiveness in the setting of childhood PCV NIP.</P> <P><B>Highlights</B></P> <P> <UL> <LI> National immunization program for PPV23 for the elderly was implemented in Korea. </LI> <LI> PPV23 was effective against IPD and NBPP for young elderly patients aged 65–74. </LI> <LI> Effectiveness of PPV23 against IPD was higher for PPV23 unique serotypes. </LI> <LI> PPV23 was non-protective against IPD caused by PCV13 serotypes. </LI> </UL> </P>

서울의 Penicillinase Producing Neisseria Gonorrhoeae 발생빈도(1994)

김재홍,안진균,정성재,김영태,김중환,김시영,이석종,이홍렬,서호석,김경훈,권혁진,정우권,고우석,이용석,안필수,오준규,오용섭 대한화학요법학회 1996 대한화학요법학회지 Vol.14 No.1

Background : In recent years gonorrhoea has been panendemic and remains one of the most common Sexually Transmitted Diseases in the world, especially in developing countries. Objective & Method : For the detection of a more effective therapeutic regimen and assessing the prevalence of Penicillinase Producing Neisseria Gonorrhoeae(PPNG), Ive have been trying to study the patients who have visited the VD Clinic of Choong-Ku Public Health Center in Seoul since 1980 by means of the chromogenic cephalosporin method. Results : In 1994, 168 strains of N. gonorrhoeae were isolated, among which 109 (64,9% ) were PPNG. Conclustion : Our results suggests that the prevalence of PPNG in Seoul is still increasing.

數種의 市販 淸凉飮料에 依한 琺瑯質 脫灰效果

김영숙,신영림,송근배,김영진 慶北大學校 齒科大學 1992 慶北齒大論文集 Vol.9 No.1

The purpose of this study was to investigate the effects of tooth enamel dissolution by commercial beverages. Five kinds of beverages(cola, cider, aquarius, boribori and sunkist orange) were selected for test medium and sixteen of extracted 3rd molar were used for tooth enamel specimens. The acidity of each beverage was determined with pH meter and the concentration of total glucose was checked with Glucose kit and U-V spectrophotometer. The dissolved calcium was determined by Atomic Absoprtion Spectrophotometer and the change of enamel surfaces were observed with Scanning Electron Microscopy(× 400 & × 1,000 magnification). All collected data were analyzed by one-way & two-way ANOVA in SPSS/PC^+ program. The obtained results were as follows: 1. The major containing acid type of cola beverage was phosphoric acid but the other beverages(cider, aquarius, boribori and sunkist) were citric acid. The pH of each beverage was lowest in cola and sport drink, cider, boribori, fruit juice in ascending order(F=205.85, p<0.001), the average pH of 5 kinds of beverage was 2.84 ±0.04, all beverages used in this experiment were low enough to decalcify the tooth enamel. The total glucose concentration of each beverage was 2.74% in aquarius, 2.78% in cider, 3.96% in sunkist, 4.23% in boribori and 4.27% in cola. 2. The average dissolved calcium concentration in 5cc of beverage was 1.54±0.12ppm/5㎖ of HNO_3 in cola, 1.76±0.38ppm in sunkist, 1.90±0.09ppm in boribori, 3.03±0.09ppm in aquarius, 3.59±0.38ppm in cider and the final calcium contents, which is extrated original calcium contents from total calcium contents after 120 minutes were highest in cola(1.27ppm) and aquarius(1.02ppm), cider(0.58ppm), sunkist(0.45ppm), boribori(0.33ppm) in the order(p<0.05). 3. The direct proportional relationship was not found between the degree of surface change on Scanning Electron Microscopy and the amount of dissolved calcium per immersion time. But the more the immerging time was lengthened, the more surface change was observed. The surface change of 120 minutes group was more remarkable than 30 and 60 minutes immerged group in each beverage.