• 한국재료학회지
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• 제29권12호
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• pp.790-797
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• 2019

To improve photocatalytic performance, CdS nanoparticle deposited TiO₂ nanotubular photocatalysts are synthesized. The TiO₂ nanotube is fabricated by electrochemical anodization at a constant voltage of 60 V, and annealed at 500 for crystallization. The CdS nanoparticles on TiO₂ nanotubes are synthesized by successive ionic layer adsorption and reaction method. The surface characteristics and photocurrent responses of TNT/CdS photocatalysts are investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-Vis spectrometer and LED light source installed potentiostat. The bandgaps of the CdS deposited TiO₂ photocatalysts are gradually narrowed with increasing of amounts of deposited CdS nanoparticles, which enhances visible light absorption ability of composite photocatalysts. Enhanced photoelectrochemical performance is observed in the nanocomposite TiO₂ photocatalyst. However, the maximum photocurrent response and dye degradation efficiency are observed for TNT/CdS30 photocatalyst. The excellent photocatalytic performance of TNT/CdS30 catalyst can be ascribed to the synergistic effects of its better absorption ability of visible light region and efficient charge transport process.

• Journal of Welding and Joining
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• 제33권6호
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• pp.6-12
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• 2015

Thermal fatigue life of the automobile exhaust manifold is directly affected by the restraint force according to the structure of exhaust system and bead shape of the welded joints. In the present study, the microstructural changes and precipitation behavior during thermal fatigue cycle of the 18wt% Cr ferritic stainless steel weld heat affected zone (HAZ) considering restraint stress were investigated. The simulation of weld HAZ and thermal fatigue test were carried out using a metal thermal cycle simulator under complete constraint force in the static jig. The change of the restraint stress on the weld HAZ was simulated by changing the shape of notch in the specimen considering the stress concentration factor. Thermal fatigue properties of the weld HAZ were deteriorated during cyclic heating and cooling in the temperature range of $200^{\circ}C$ to $900^{\circ}C$ due to the decrease of Nb content in solid solution and coarsening of MX type precipitates, laves phase, $M_6C$ with coarsening of grain and softening of the matrix. As the restraint stress on the specimen increased, the thermal fatigue life was decreased by dynamic precipitation and rapid coarsening of the precipitates.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.649-652
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• 2005

The camera cellular phone has a large portion of cellular phone market in recent year. The variety of a customer demand makes a fast model change and the spatial resolution is changed from VGA to multi-mega pixel. The 1.3 mega pixel (MP) camera cellular phone was first released into the Korean market in October 2003. The major cellular phone companies released a 2MP camera cellular phone that supports zoom function and a 2MP camera cellular phone is settled down with the Korea cellular phone market. It makes a keen competition in price and demands automation for phone camera module. There is an increasing requirement for the automatic assembly to correspond to a fast model change. The hard automation techniques that rely on dedicated manufacturing system are too inflexible to meet this requirement. Therefore in this study, this system is designed with the flexibility concept in order to cope with phone camera module change. The system has a same platform that has X-Y-Z motion or X-Z motion with ${\mu}m$order accuracy. It has a special gripper according to the type of a component to be put together. If the camera model changes, the gripper may be updated to fit for the camera module. The controller of this system acquires the data sets that have the information about the assembly part by the tray. This information is obtained ahead of an inspection step. The controller excludes an inferior part to be assembled by using this information to diminish the inferior goods. The assembly jig used in this system has a function of self adjustment that reduces the tact time and also diminish the inferior goods. Finally, the intelligent assembly system for phone camera module will be designed to get a flexibility to meet model change and a high productivity with a high reliability.

• 대한전자공학회논문지SD
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• 제38권3호
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• pp.236-241
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• 2001

스페클 패턴은 다중모드 광섬유 내를 전파하는 모드 사이의 간섭현상 때문에 발생하는 검은 무늬로서, 외부 섭동 (perturbation)의 크기에 따라 패턴이 바뀌게 된다. 이 현상을 이용하여 본 연구에서는 스페클 센서를 제작하여 실험을 통해 시설물을 원거리, 실시간 원격 감시가 가능하고 매우 민감한 침입자 센서로 응용 가능함을 확인하였다. 본 연구에서는 감도를 높이고 구조를 간단하게 하기 위해, 공간필터를 사용하는 대신 광검출기 홀더를 길이 가변이 가능하도록 지그를 제작하여 사용하였으며, 정류기와 FVC를 사용하여 외부 섭동의 지속시간과 크기를 알 수 있었다.

• 대한치과교정학회지
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• 제41권2호
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• pp.138-146
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• 2011

The purpose of this article is to introduce a new virtual orthodontic treatment (VOT) system, which can be used to construct three-dimensional (3D) virtual models, establish a 3D virtual setup, enable the placement of the virtual brackets at the predetermined position, and fabricate the transfer jig with a customized bracket base for indirect bonding (IDB) using the stereolithographic technique. A 26-year-old woman presented with anterior openbite, crowding in the upper and lower arches, and narrow and tapered upper arch, despite having an acceptable profile and balanced facial proportion. The treatment plan was rapid palatal expansion (RPE) without extraction. After 10 days of RPE, sufficient space was obtained for decrowding. After a 10-week retention period, accurate pretreatment plaster models were obtained using silicone rubber impression. IDB was performed according to the protocol of the VOT system. Crowding of the upper and lower arches was effectively resolved, and anterior openbite was corrected to normal overbite. Superimposition of the 3D virtual setup models (3D-VSM) and post-treatment 3D virtual models showed that the latter deviated only slightly from the former. Thus, the use of the VOT system helped obtain an acceptable outcome in this case of mild crowding treated without extraction. More cases should be treated using this system, and the pre- and post-treatment virtual models should be compared to obtain feedback regarding the procedure; this will support doctors and dental laboratory technicians during the learning curve.

• 한국지진공학회논문집
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• 제20권3호
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• pp.155-162
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• 2016

Observations of the damages to high-rise reinforced concrete (RC) wall building structures caused by by recent earthquakes in Chile ($M_w$ 8.8, February 2010) and New Zealand (February 2011, $M_L$ 6.3) have generally exceeded expectations. Firstly, this study estimated the seismic damage levels of 15-story RC box-type wall building structures using the analytical models calibrated by the results of a shaking table test on a 1:5 scale 10-story RC box-type wall building model. Then, the seismic fragility analysis of the prototype model was conducted by using the SAC/FEMA method and the incremental dynamic analysis (IDA). To compensate for the uncertainties and variability of ground motion and its impacts on the prototype model, in the SAC/FEMA method, a total of 61 ground motion records were selected from 20 earthquakes, with a magnitude ranging from 5.9 to 8.8 and an epicentral distance ranging from 5 to 105km. In the IDA, a total of 11 ground motion records were used based on the uniform hazard response spectrum representing a return period of 2,475 years. As a result, the probabilities that the limits of the serviceability, damage control, and collapse prevention would be exceeded were as follows: from the SAC/FEMA method: 79%, 0.3%, and 0%, respectively; and from the IDA: 57%, 1.7%, and 0%, respectively.

• 대한치과보철학회지
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• 제46권3호
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• pp.261-268
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• 2008

STATEMENT OF PROBLEM: Detachment of the magnetic assembly from the denture base has been a problem in magnetic overdenture patients. PURPOSE: The objectives of this study were to compare the dislodging force by the fixing materials and the designs of the magnetic assembly, and to compare the effect between the fixing materials and the designs of the magnetic assembly. MATERIAL AND METHODS: Two fixing materials, Jet denture repair $acrylic^{(R)}$ and Super-$Bond^{(R)}$ C&$B^{(R)}$ and two types of magnetic assembly designed with or without wing were used. Each magnetic assembly was fixed in the chamber of the denture base resin block ($Lucitone^{(R)}$199) with each fixing material respectively. These specimens were thermocycled 2,000 cycles in the water held at $4^{\circ}C$ and $60^{\circ}C$ with a dwell time of 1 min each time. Each specimen was seated in a testing jig and then a push-out test was performed with a universal testing machine at a cross head speed of 0.5 mm/min to measure the maximum dislodging forces. RESULTS: Comparing the fixing materials, Super-Bond C&$B^{(R)}$ showed superior dislodging force than Jet denture repair $acrylic^{(R)}$. Comparing the design of the magnetic assemblies, the wing design magnetic assembly showed better dislodging force. Combination of the Super-Bond C&$B^{(R)}$ as a fixing material and wing design magnetic assembly revealed a greatest dislodging force. The kind of fixing material was more influential than the type of magnetic assembly. CONCLUSION: The dislodging force of Super-Bond C&$B^{(R)}$ was significantly higher than Jet denture repair $acrylic^{(R)}$. And the dislodging force of magnetic assembly which have wing design was significantly higher than magnetic assembly which have no wing design.

• 전자공학회논문지CI
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• 제44권3호
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• pp.23-30
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• 2007

RFID(Radio Frequency Identification)란 정보를 읽거나 쓰기 위한 반도체 칩을 내장하고 정보의 전송을 위해 안테나를 사용하는 무선주파수 시스템을 말한다. 또 이렇게 전송된 정보를 수집 및 여과하는 미들웨어, RFID코드와 관련된 정보를 저장하고 있는 객체정보서버, 이력정보가 저장된 위치정보를 가진 객체이력서버, 코드와 관련된 물품정보가 있는 서버의 위치를 알려주는 RFID 검색서비스 등이 RFID 서비스 네트워크를 구성한다. RFID 태그가 부착된 물품에 대한 생산자 정보, 유통 경로, 상태 등의 정보를 저장하여 활용하기 위한 곳을 말하며 DB 시스템을 사용하는 것이 일반적이다. 따라서 검증 실험에서 측정분석 결과는 리더간 전파 간섭이 발생하지 않기 위해서는 안테나단에서 수신되는 power 레벨이 최소한 -55dBm을 유지해야만 전파 간섭이 발생하지 않을 것으로 생각되고, 안테나와 테그의 인식 거리는 최대 7m 까지도 가능하지만, 원활한 인식을 위해서는 3-4m이내에서 사용되어야 바람직 할 것으로 생각된다.

• 대한치과보철학회지
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• 제41권1호
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• pp.48-60
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• 2003

The purpose of this study was to compare the fracture strength of the IPS Empress ceramic crown according to the occlusal depth (1.5mm, 2.0mm, 2.5mm) and axial inclination ($4^{\circ},\;8^{\circ},\;12^{\circ}$) of the lower First Molar. After 10 metal dies were made for each group, the IPS Empress ceramic crowns were fabricated and cemented with resin cement(Bistite resin cement, Tokuyama Soda Co. LTD., Japan). The cemented crowns were mounted on the testing jig with inclination of 30 degrees and the universal testing machine(Zwick Z020, Zwick, Germany)was used to measure the fracture strength. The results of this study were as follows : 1. The fracture strength of the ceramic crown with 2.5mm depth and $12^{\circ}$ inclination was the highest (1789 N). Crowns of 1.5mm depth and $4^{\circ}$ inclination had the lowest strength (1091 N). 2. There were no significant differences in the fracture strength by axial inclination of the same occlusal depth group. 3. Most fracture lines began at the loading area and extended through proximal surface perpendicular to the margin, irrespective of occlusal depth. Size of fragment was affected by the amount of occlusal reduction.

• 한국전자파학회논문지
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• 제24권4호
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• pp.384-393
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• 2013

본 논문에서는 집중 소자를 이용한 광대역 평판형 마이크로파 바이어스-티의 설계를 보였다. 설계된 바이어스-티는 DC 블록과 RF 초크로 구성된다. DC 블록용 커패시터는 광대역으로 동작하는 커패시터를 사용하였고, DC 공급 및 RF 초크용 인덕터는 서로 다른 자기 공진 주파수(SRF: Self Resonance Frequency)를 가지는 인덕터들을 직렬로 연결하였다. RF 초크에서 집중 소자들의 직렬 공진에 의하여 발생하는 신호의 손실을 병렬의 저항과 커패시터를 연결하여 해결하였다. 설계된 바이어스-티는 1608 칩 형태의 집중 소자들을 이용 조립하여 제작하였다. 측정은 커넥터의 손실과 영향을 제거하기 위하여 Anritsu 3680K jig에 연결하여 측정하였다. 제작된 바이어스-티는 10 MHz~18 GHz의 광대역에서 동작하고, 측정된 반사 손실이 -15 dB 이하를 가지며, 삽입 손실은 -1.5 dB 이하인 것을 확인하였다.