레진전장관의 금속면 처리방법 레진과 금속간 접착강도에 미치는 영향

최낙준,방몽숙,Choi Nak-Joon,Vang Mong-Sook 대한치과보철학회 1994 대한치과보철학회지 Vol.32 No.4

The purpose of this experiment was to determine the effects of various surface treatments on veneering resin to metal bond for Ni-Cr alloy. The metal surfaces were treated as follows, Group 1 : Ground with carborudum point and followed by silicoating Group 2 : Sandblasted with $50{\mu}m$ aluminum oxide and followed by silicoating Group 3. Sandblasted with $250{\mu}m$ aluminum oxide and followed by silicoating Group 4 : Beaded with $200{\mu}m$ retention structures and followed by silicoating Group 5 : Silicoated in as cast condition Group 6. Beaded with $200{\mu}m$ retention structures only All specimens were veneered with resin. Each group was consisted of 20 specimens. 10 specimens were storaged in $37^{\circ}C$ water for 3 days and the rest 10 specimens were thermocycled 1000 times at temperature of $5^{\circ}C\;to\;55^{\circ}C$. The effects of various surface treatments on the bond strength between resin and metal interface were studied by means of four-point flexure test. The specimens which bad been ground with carborundum point. sandblasted with $50{\mu}m$ and $250{\mu}m$ aluminum oxide. beaded with $200{\mu}m$ retention structures and not been treated were observed with SEM. The following results were obtained 1. The bond strength of groups 2, 3, 4 and 6 were higher than the that of groups 1 and 5 (p<0.05) in the case of being storaged in $37^{\circ}C$ water for 3 day and there was no statistically significant difference in bond strength among groups 2, 3, 4 and 6. and between groups 1 and 5 (p>0.05). 2. The bond strength of the case of being thermocycled decreased in the following orders : groups 2, group 4, group 3, group 6, group 1, group 5 and there was no statistically significant difference in bond strength among groups 2, 3 and 4, between groups 1 and 5 (p>0.05). 3. A statistical difference in bond strength of each group between storaged and being thermocycled was demonstrated for group 5 (p<0.05). 4. The treated surfaces of groups 2, 3 and 4 had more fine undercut than that of groups 1 and 5 with SEM.

미백 처리된 치아의 표면처리법이 레진과의 결합에 미치는 영향

최낙준,방몽숙,박하옥,Choi Nak-Joon,Vang Mong-Sook,Park Ha-Ok 대한치과보철학회 2002 대한치과보철학회지 Vol.40 No.5

The purpose of this study was to estimate the effect of a bleaching agent on tooth surfaces and to evaluate the resin bond strength according to different surface treatments on bleached teeth. To prepare for the experimental samples, first, extracted human third molars were used and the body portions of the crowns were cut into four equal-sized specimens. Next, each specimen was mounted in an plastic bottle with self-cured resin and highly polished to have them reveal the enamel or dentin surfaces. Then, the enamel(E) and dentin(D) specimens were divided into four ; 1) non-bleached, laser-treated(NBLA) group 2) bleached, laser-treated(BLLA) group 3) non-bleached, acid-treated(NBAC) group and 4) bleached, acid-treated(BLAC) group. Here, $opalescence^{(R)}$ (10% carbamide peroxide) was used for bleaching agent. The treated specimens were observed by confocal laser scanning microscopy and bonded with composite resin for shear bond test. The following results were obtained from this experiment : 1. Compared with the ENB group, the EBL group was shown be dyed about $20{\mu}m$ deeper with rhodamine B. The DBL group appeared to be caved in at the entry part of the dentinal tubules, was dyed about $20{\mu}m$ deeper and $5{\mu}m$ wider in diameter, compared with the DNB group. 2. In comparison with the EBLAC group, the ENBAC group looked evenly bonded with the resin, while the DNBAC group, compared to DBLAC group, was observed to have its resin tags penetrated about $50{\mu}m$ deeper. Other than those, however, no observable differences between ENBLA and EBLLA group or between DNBLA and DBLLA group were found. 3, At the shear bond test, the ENBAC group was shown to have statistically significant higher shear bond strength than the EBLAC group(p<0.05). No statistically significant differences between the ENBLA and the EBLLA groups were observed(p>0.05). 4. At the shear bond test, the DNBAC group was shown to have statistically significant higher shear bond strength than the DBLAC group(p<0.05). No statistically significant differences between the DNBLA and the DBLLA groups were observed(p>0.05). The in vitro observations above suggest that tooth-bleaching procedure brings a certain change on enamel and dentin surfaces and it weakens the shear bond strength with composite resin when the bleached tooth was acid-treated.

WinBlade 를 이용한 수평축 풍력터빈 유동-구조 해석 자동화

최낙준(NAK JOON CHOI),이동화(DONG HWA LEE),최경호(KYOUNG HO CHOI),김재성(JAE SUNG KIM) (사)한국CDE학회 2014 한국 CAD/CAM 학회 학술발표회 논문집 Vol.2014 No.8

Renewable energy has been actively studied as the new energy sources to replace fossil fuels recently. Among them, the wind energy is evenly distributed in the worldwide comparing to other renewable energy. The main parts of the horizontal axis wind turbine among the various wind turbine system are a turbine blade, main shaft, and tower. Design and simulation analysis can be very important role to evaluate the performance and structural stability of the wind turbine. However, the software of component design, system design and simulation is mostly dependent on the oversea products in Korea. Therefore, the design and simulation software developed on domestic is required at this time. For this reason, WinBlade was developed to be able to conduct the design and simulation of main components of wind turbine without expert knowledge. The objective in this paper is automation of design and simulation of main components of wind turbine using WinBlade.

자동집하시설의 top-down 관로망 모듈 설계

최낙준(Nak-Joon Choi),최경호(Kyoung-Ho Choi),서상호(Sang-Ho Suh) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.11

Pneumatic waste collection system (hereinafter “PWCS”) will be popularized by solving sanitary problems of conventional door-to-door waste collection system and meeting quality of living. Initial conceptual design and investigation of PWCS are very important because of difficulty in pipeline modification and security of design life over 20 years after installation of PWCS. Module design of PWCS is based on sub-assemblies and parts with parametric design and it can be re-used during modeling and design process. Module design can provide 3D modeling for computational fluid dynamics and structural analysis for PWCS performance evaluation effectively.

CFD를 활용한 6 MW 해상풍력발전단지의 풍력터빈 이격거리에 따른 공기역학적 출력 변화연구

최낙준(Nak-Joon Choi),남상현(Sang-Hyun Nam),정종현(Jong-Hyun Jeong),김경천(Kyung-Chun Kim) 한국마린엔지니어링학회 2011 한국마린엔지니어링학회지 Vol.35 No.8

본 논문은 2 MW급 풍력터빈 3기로 구성된 6 MW 해상풍력발전단지의 풍력터빈 이격거리에 따른 공기역학적 출력 변화를 전산유동해석을 활용하여 연구한 것이다. 육상 뿐만 아니라 해상풍력발전단지에 있어서 레이아웃 설계는 풍력발전단지 초기 투자비, 년간 발전량 및 유지보수비에 영향을 끼치는 핵심 인자이다. 각 풍력터빈 로터에 대해서 모멘텀 소스를 가지는 액츄에이터 디스크가 아닌 완전한 3-D 모델에 대해서 전산유동해석 기법을 적용하여 연구하였으며 이는 기술적으로 큰 의미를 가진다. 본 논문의 연구결과는 향후 해상풍력발전단지 레이아웃 설계에 유용하게 적용될 수 있을 것이다. This paper presents aerodynamic power outputs of wind turbine of 6 MW wind farm composed of 3 sets of 2 MW wind turbine according to the separation distance by using CFD. Layout design including offshore wind farm and onshore wind farm is key factor for the initial investment cost, annual energy production and maintenance cost. For each wind turbine rotor, not actuator disc model with momentum source but full 3-dimensional model is used for CFD and it has a great technical meaning. The results of this study can be applied to the offshore wind farm layout design effectively.

도서지역에 적합한 1㎾급 수평축 풍력터빈 설계 및 유동해석

이준용(Jun-Yong Lee),최낙준(Nak-Joon Choi),윤한용(Han-Yong Yoon),김일수(Ill-Soo Kim),최영도(Young-Do CHOI) 한국유체기계학회 2010 유체기계 연구개발 발표회 논문집 Vol.2010 No.12

해상풍력발전시스템 타워서비스리프트 설계 및 구조해석

최영도(Young-Do Choi),손성우(Sung-Woo Son),장호철(Ho-Choul Jang),최낙준(Nak-Joon Choi) 한국마린엔지니어링학회 2012 한국마린엔지니어링학회지 Vol.36 No.1

본 연구 결과는 해상풍력발전시스템 타워 내부에 설치하는 서비스리프트의 설계 및 구조해석에 대한 내용이며, 공학적 설계법 및 수치해석에 의한 구조해석을 통하여 서비스리프트의 안정성 및 신뢰성을 확인하였다. 설계의 주된 내용은 설계 허용한계 이내에서 만족스러운 성능으로 지상으로부터 타워상부의 해상풍력터빈 너셀까지 작업자와 수리보수용 장비를 안전하게 수송할 수 있는 충분한 능력을 확보하는 것이다. 구조해석을 통하여 서비스리프트 캐빈 및 안전장치의 총변형량과 등가응력에 대해서 검토하여 설계 시 적용한 안전율의 타당성을 검토하였다. The purpose of this study is to establish a design method of tower service lift for offshore wind power system, as well as to conduct structure analysis of the service lift system. The service lift system will be built in the internal area of tower of the offshore wind power system. Design and structure analysis for the tower service lift system are conducted to clarify the stability and reliability of the system. Main objective of the design is to secure sufficient capability of transportation of workers and equipment with satisfactory performance within the designed tolerance limit. Total deformation and equivalent stress of the lift system by external load are examined using the results of structure analysis.

바람의 유입각도에 따른 건물 설치형 수평축 풍력발전기 성능에 대한 CFD 연구

허영근(Young Gun Heo),최낙준(Nak Joon Choi),최경호(Kyung Ho Choi),김경천(Kyung Chun Kim) 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.5-2

Flow Analysis on a 1kW-class Horizontal Axis Wind Turbine Blade for Hybrid Power Generation System

이준용(Lee, Jun-Yong),최낙준(Choi, Nak-Joon),최영도(Choi, Young-Do) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05

This study is to develop a 1kW-class small wind turbine blade which will be applicable to relatively low speed regions. For this blade, a high efficiency wind turbine blade is designed and a light and low cost composite structure blade is adopted considering fatigue life. In this study, shape design of 1kW-class small wind turbine blade for hybrid power generation system is carried out by BEMT(blade element momentum theory). X-FOIL open software was used to acquire lift and drag coefficients of the 2D airfoils used in power prediction procedure. Moreover, pressure and velocity distributions are investigated according to TSR by CFD analysis.

K-겹 교차 검증과 서포트 벡터 머신을 이용한 고무 오링 결함 검출 시스템

이용은(Yong Eun Lee),최낙준(Nak Joon Choi),변영후(Young Hoo Byun),김대원(Dae Won Kim),김경천(Kyung Chun Kim) 한국가시화정보학회 2021 한국가시화정보학회지 Vol.19 No.1

In this study, the detection of rubber o-ring defects was carried out using k-fold cross validation and Support Vector Machine (SVM) algorithm. The data process was carried out in 3 steps. First, we proceeded with a frame alignment to eliminate unnecessary regions in the learning and secondly, we applied gray-scale changes for computational reduction. Finally, data processing was carried out using image augmentation to prevent data overfitting. After processing data, SVM algorithm was used to obtain normal and defect detection accuracy. In addition, we applied the SVM algorithm through the k-fold cross validation method to compare the classification accuracy. As a result, we obtain results that show better performance by applying the k-fold cross validation method.