Cutting performance of tungsten carbide tools coated with diamond thin films after etching for various times

Kim, Jong Seok,Park, Yeong Min,Bae, Mun Ki,Kim, Chi Whan,Kim, Dae Weon,Shin, Dong Chul,Kim, Tae Gyu World Scientific Publishing Company 2018 Modern physics letters. B, Condensed matter physic Vol.32 No.20

<P>In this study, diamond thin films were deposited on tungsten carbide tools using surface-wave plasma-enhanced chemical vapor deposition (SWP-CVD). To eliminate the adverse effects of cobalt on the diamond deposition process, the cobalt was removed from the surface of the tools by etching with Murakami’s reagent for various times (30, 60, and 120 min). The cutting performance of the untreated and the diamond-coated WC tools was examined by performing cutting test on carbon fiber-reinforced plastic (CFRP). The results showed that all the diamond-coated tools exhibited great improvement on the durability and wear resistance compared to the uncoated one. In addition, the diamond-coated tool lift time is found to be proportional to the etching time. An increase more than twofold has been achieved when the etch time was increased from 30 min to 120 min.</P>

설계기준자동차 유형별 회전교차로 사고분석 및 논의

이민영, 박병호 충북대학교 산업과학기술연구소 2018 산업과학기술연구 논문집 Vol.32 No.2

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정신분열병 환자들의 自己灣入에 관한 예비 연구

박성봉,김영미,전성일,이기철,김영훈,정영조,이영렬,이정호,최영민 大韓神經精神醫學會 1997 신경정신의학 Vol.36 No.6

목 적 : 정 신분열병 환자의 자기만입 정도에 영향을 미치는 인구학적 변인들 및 질병연관 변인들을 규명해 보고자 하였다. 또한. 환자들의 자기만입과 병식 사이의 연관성. 자기만입과 자존심 사이의 연관성을 알아보고자 하였다. 방 법 : 정신과 의사가 병록지와 면담을 통하여 대상 정신분열병 환자들의 인구학적 변인들 및 질병연관 변인들에 관한 자료를 얻고 환자들의 병식 정도를 평가한 후, 환자들로 하여금 자기보고형의 자기만입 척도와 자존심 척도를 시행하게 하였다. 총 111명의 환자가 연구대상으로 선택되었다. 결과: . 1) 여자가 남자보다 유의하게 높은 자기만입 척도 점수를 나타내었다 2) 질병연관 변인들 중 하위집단 사이에 자기만입 척도 점수의 유의한 차이를 보이는 변은 없었다. 3) 자기만입 척도 점수와 병식 점수 사이에 유의한 상관관계가 없었다. 4) 자기만입 척도 점수와 자존심 척도 점수 사이에 유의한 역상관 관계를 보였다. 결 론 : 본 예비 연구의 결과로 보아 정신분열 병 환자의 병식이 부족한 상태에서도 자기만입이 진행될 수 있으며. 자기만입이 심할수록 환자의 자존심이 저하되는 것으로 생각된다. 또한 여자 환자들이 남자 환자들보다 자기만입에 더 취약한 것으로 생각된다. 따라서 정신분열 병 환자의 이해와 치료를 위하여 자기만입에 관한 지속적인 연구가 필요할 것으로 생각된다. objective : This study was conducted to identify demographic variables and illness related variables which may affect the severity of self-engulfment in the patients with schizophrenia. We also studied the relationship between self-engulfment and insight, and the relationship between self-engulfment and self-esteem. Methods : Data on demographic variables and illness related variables for the subjects were gathered from hospital records and clinical interviews by the psychiatrists. Degree of insight for the subjects was assessed through clinical interviews by the psychiatrists. Degree of self-engulfment and self-esteem for the subjects was assessed from the self-engulfment scale and the self-esteem scale respectively. A total of 111 patients with schizophrenia were selected for statistical analysis. Results 1) The females exhibited significantly higher scores than the males on the self-engulfment scale. 2) There was no illness related variable, which exhibited a significant difference among subgroups on the self-engulfment scale. 3) There was no significant correlation between the self-engulfment scores and the insight 4) There was a significantly inverse correlation between the self-engulfment scores and the self-esteem scores. Conclusion : The results of this preliminary study suggest that self-engulfment may develop despite lack of insight and that there was inverse relationship between self-engulfment and self-esteem in the patients with schizophrenia. It also suggests that females are more subject to self-engulfment than males. So, authors suggest that it is valuable to do further studies of self-engulfment in the patients with schizophrenia.

건조환경에 기반한 회전교차로 사고분석

이민영, 박병호 충북대학교 산업과학기술연구소 2018 산업과학기술연구 논문집 Vol.32 No.2

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치과주조용 Ti-Zr-Cr계 합금에서 Cr 함량변화가 부식저항성에 미치는 영향

박영준,강후원,이용렬,송호준,김민강 大韓齒科器材學會 2004 대한치과재료학회지 Vol.31 No.4

The purpose of this study was to develop new dental casting titanium (Ti) alloys having an excellent mechanical properties and good corrosion resistance as a substitute for c.p Ti and Ti-6Al-4V alloy (control groups). Ti-20Cr, Ti-2OZr and Ti-20Zr-XCr (X=2, 5, 10, 15) alloys (experimental groups) were designed for dental casting Ti alloys. Prior to casting prccedure, mother alloys were prepared by using vacuum arc melting with skull melting method. Argon-arc melting and argon/vacuum-pressure casting machine were used for making the specimens. The hardness, microstructure, and corrosion resistance were evaluated by using Vickers microhardness measurement, FE-SEM, and anodic polarization test. The results were as follows: 1. The Vickers microhardness (Hv) of Ti and Ti-6Al-4V alloy showed the values of 210 and 352, and Ti-20Cr and Ti-20Zr alloys showed the values of 341 and 259, respectively. As the Cr content increased from 0 to 15 % in Ti-20Zr-XCr (X=0, 2, 5, 10, 15) alloys, the Hv increased from 259 to 298, 457, 344, and 351, respectively. The microstructure of Ti-20Zr-XCr specimens showed significant difference by the concentration changes of Cr content showing acicular crystalline structure for Ti-20Zr-2Cr and Ti-20Zr-5Cr, and equiaxed crystalline structure for Ti-20Zr-10Cr and Ti-20Zr-15Cr. 2. Open-circuit potentials (E_(∝)) were rapidly decreased followed by steadiness as time elapse in all experimental groups except in Ti-20Z group. Ti-2OZr group showed an increase in E_(∝), from the first. 3. In potentiodynamic anodic polarization tests, all experimental groups showed more noble corrosion potential (E_(corr) than that of Ti-6Al-4V, and more basic E_(corr) than that of Ti. Especially, Ti-20Zr-10Cr alloy showed most favorable corrosion resistance among Ti-Zr-Cr alloys. 4. For Ti-20Zr-10Cr, Ti-20Zr-15Cr, and Ti-20Cr groups, which have more than 10% Cr content, the secondary corrosion potential shifted to noble direction in larger amounts than in the cases of control and other experimental groups. From these results, it was concluded that newly formulated Ti-20Zr-10Cr experimental alloy have adequate hardness and high corrosion resistance, and this alloy is promising candidate for a successful dental casting alloy.

볼링선수의 체격·체조성·운동능력과 경기력 비교

최민동,박세환,이영춘,박일규 한국스포츠리서치 2003 한국 스포츠 리서치 Vol.20 No.1

1. Comparison between man and woman bowling player's bodyshape, motor ability, body composition and game score. 1) Generally, man's physique was better than woman's. 2) Man's grip strength, back strength, vertical jump, standing long jump, game score are better than woman's. 3) Woman has higher percent body fat, man has higher percent of total body water and lean body mass. 2. Comparison between man and woman bowling player's bodyshape, motor ability, body composition and game score from their difference of age. 1) Comparison of man's bodyshape has shown this result that 19years old bowling player had better ability of upper limb length and lower length than 17, 18 years. 2) Comparison of man's motor ability have shown this result that 17, 18, 19 years old player have the highest grip strength and motor ability in regular sequence,17 years old player has the best ability at zigzag run, 18 years old player has best ability at twist and touch. 3) Comparison of Woman's motor ability has shown this result that in order to 17, 18, 19 years old player has highest grip strength, back strength vertical jump, standing long jump, sit-ups, block transfer. 4) Comparison of capacity of a game score has shown this result that man and woman player who are in 17, 18, 19 years old have the highest ability in regular sequence.

치아미백제가 치과용 심미수복재의 색상에 미치는 영향

정석민,김원재,박영준 전남대학교 치과대학 2000 전남치대논문집 Vol.12 No.1

The purpose of this study was to evaluate the effects of commercial home tooth bleaching agent application on the color of esthetic restorative materials. In order to evaluate the effect of intraoral aging of these materials(3 composite resins; Palfique Estelite??, Prodigy??, TPH Spectrum??, and 1 compomer ; Dyract??) on the degree of lightness change induced by tooth bleaching agents, each material groups were subdivided (thermocycled and non-thermocycled). Three specimens from each material group were treated with 5 types of bleaching agents (Nite White Excel??, Insta-Brite??, Opalescence??, Plus White?? and StarBrite Contrast_EM??) and evaluated. The results were as follows: 1. Bleaching agent treatments applied to esthetic restorative materials which were not thermocycled before the treatment induced various ΔL^* values as low as lesser than 1 and as high as greater than 4. On the other hand, the second material group (thermocycled before bleaching agent treatments) induced ΔL^* values lesser than 2, except in the case of Insta-Brite treated Dyract group. 2. In the grups that were thermocycled before bleaching agent treatment, Prodigy showed the lowest increase in L^* by all the bleaching agent treatments. Conversely, Dyract demonstrated a higher increase in L^* than the other esthetic restorative materials by Insta-Brite, Opalescence, Plus White bleaching agent treatments. 3. In the groups that were not thermocycled before bleaching agent treatment, Prodigy showed a lower increase in L^* when treated with Nite White Excel, Insta-Brite, Opalescence. On the other hand, TPH Spectrum displayed a higher increase in L^* except when treated with Plus White. These results demonstrated that all commercial tooth bleaching agents have appreciable bleaching effect on teeth, and induces color changes on restorative materials to varying degrees depending on the combination of restorative material and the tooth bleaching agents. More caution should be taken concerning these effects in the case of recently restored esthetic materials.

교정용 광중합형 및 화학중합형 레진접착제의 전단결합강도와 파절양상에 대한 연구

이민화,박영준,양규호 大韓小兒齒科學會 1996 大韓小兒齒科學會誌 Vol.23 No.2

Light-cured orthodotic composite resin has been widely advertised recently for use in bonding brackets.However,the curability of light-cured resin waves are diffused through metal brackets in questionable. The purposes of this study were to evaluate shear bond strenght and failure patterns of visible light-cured resin(Lightbond) and chemically cured-resin(Mono-Lok 2),and to determine the relative value of light-cured resin as an alternative to conventional chemically cured resin.Each of the two resins was tested on twently extracted human first premolars.Standard edgewise mental brackets were bonded to the teeth in accordance with the manufacturers' recommendation.After bonding,the teeth were stored for 24 hours at 37℃,100% huminity.The shear bond strenght was tested with a universal testing machine(Instron 4302),at 0.5mm/min crosshead speed.After debonding,brackets and enamel surfaces were examines with a scanning electron microscope and a stereoscopic microscope. The results were as follows: 1.Mental brackets bonded with Lightbond showed statistically highershear bond strenght than mental brackets bonded with Mono-Lok 2. 2.The predominant failure site in Lightbond was the enamel-resin interface,and in Mono-Lok 2 it was the resin itself. 3.Enamel cracks were not found in any specimen. The above results suggest that direct bonding of metal brackets enamel with light-cured resin bonding agent can be used effectively in clinics.

가축보험의 위험가격에 대한 생산자 선호 분석

정민국,허덕,박영수 韓國農業政策學會 1998 농업경영정책연구 Vol.25 No.1

치아미백제가 우치의 색상에 미치는 영향

정석민,박경희,박영준 대한치과기재학회 2001 대한치과재료학회지 Vol.28 No.1

The purpose of this study was to evaluate the effects of commercial home-tooth bleaching agents in the color of tooth. Thirty sound extracted bovine teeth were randomly divided into six groups. The color differences between before and after treatment with four types of tooth bleaching agents (Nite White ExcelR, Insta-BriteTM, OpalescenceR, and Plus WhiteR), one type of whitening toothpaste (Natural WhiteR) and untreated control group were evaluated. The results were as follows; 1.By 2 week home tooth bleaching agent applications, the values (L*) of bovine teeth increased as high as 2.18 ∼ 6.73. 2.Insta-Brite induced significantly greater ΔL* and ΔE* than other tested groups by 2 week bleaching agent treatments(p<0.01). 3.Plus White which was applied for 5 minutes twice a day for 2 weeks induced significantly lesser ΔL* (2.18) and ΔE* (2.80) than those in Insta-Brite (ΔL*=5.30, ΔE*=6.73), Nite White Excel (ΔL*=4.24, ΔE*=4.90), Opalescence (ΔL*=3.78, ΔE*=4.92) which were applied for 8 hours a day for 2 weeks (p<0.01). These results demonstrate that all the commercial home-tooth bleaching agents have appreciable bleaching effect on bovine teeth, and the effects of home-tooth bleaching agents which are used during night time are affected by viscosity as well as content of carbamide peroxide. The whitening effect of home tooth bleaching agents that are used through nighttime is greater than that of short time-applying tooth bleaching agent.