• The Journal of Korean Academy of Prosthodontics
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• v.52 no.3
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• pp.165-176
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• 2014

Purpose: The effects of desensitizing agent are often for a short duration. One of the reasons is believed to be wear of desensitizing agent by tooth brushing. To reduce the wear and make the duration longer, dental bonding resin was applied and the changes of dentin permeability after toothbrushing were measured. Materials and methods: Extracted teeth free from caries were chosen. Coronal dentin discs with thickness of 1 mm were prepared. Using the split chamber device developed by Pashely, hydraulic conductance and scanning electron microscope images (SEM) were compared and contrasted before and immediately after the application of desensitizing agent and bonding resin and then after equivalent tooth brushing of 1 week, 2 weeks, and 6 weeks. Four commercially available desensitizing agents were used in this study; they were All-Bond 2, Seal & Protect, Gluma, and MS Coat. And Dentin/Enamel Bonding resin (Bisco Inc.) was used. The results of this study are as follows. Results: On all specimens, the hydraulic conductance decreased after the application of tooth desensitizing agent and bonding resin. Compared with the specimens treated only with desensitizer, the specimens treated with All-Bond 2, Gluma, MS Coat and plus D/E bonding resin had a little increase in hydraulic conductance after 1, 2 and 6-week tooth brushing. In case of Seal & Protect, the specimens showed the same result only after 6-week tooth brushing. On examination of SEM, the dentinal tubule diameter had decreased after treatment of desensitizing agents and bonding resin. And the specimens treated with All-Bond2, Seal&Protect, Gluma, MS Coat and plus D/E bonding resin had an significant decrease in diameter of dentinal tubule after 6-week tooth brushing. Conclusion: According to the results of this study, it is effective to use bonding resin after application of desensitizer in reducing the wear by tooth brushing and making the duration longer. In this study, just 6-week tooth brushing was performed, and it is not enough to regard it as a long-term data. So further study is needed and more perfect method for treating dentin hypersensitivity should be developed.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.336-340
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• 1999

Glasses in the system $CaO-TiO_2-SiO_2-Al_2O_3-ZrO_2-B_2O_3$ were investigated to find the glass seal compositions suitable for use in the planar solid oxide fuel cell (SOFC). Glass-ceramics prepared from the glasses by one-stage heat treatment at $1,000^{\circ}C$ showed various thermal expansion coefficients (i,e., $8.6\times10^{-6^{\circ}}C^{-1}$ to $42.7\times10^{-6^{\circ}}C^{-1}$ in the range 25-$1,000^{\circ}C$) due to the viscoelastic response of glass phase. The average values of contact angles between the zirconia substrate and the glass particles heated at 1,000-$1,200^{\circ}C$ were in the range of $131^{\circ}\pm4^{\circ}$~$137^{\circ}\pm9^{\circ}$, indicating that the glass-ceramic was in partial non-wetting condition with the zirconia substrate. With increasing heat treatment time of glass samples from 0.5 to 24 h at $1,100^{\circ}C$, the DC electrical conductivity of the resultant glass-ceramics decreased from at $800^{\circ}C$. Isothermal hold of the glass sample at $1100^{\circ}C$ for 48h resulted in diffusion of Ca, Si, and Al ions from glass phase into the zirconia substrate through the glass/zirconia bonding interface. Glass phase and diffusion of the moving ion such as $Ca^{2+}$ in glass phase is responsible for the electrical conduction in the glass-ceramics.

• Korean Journal of Materials Research
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• v.17 no.7
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• pp.366-370
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• 2007

Silicon nitride ($Si_3N_4$) ceramics have been considered for various components of nuclear power plants such as the mechanical seal of a reactor coolant pump (RCP), the guide roller for a control rod drive mechanism (CRDM), and a seal support, etc. Corrosion behavior of $Si_3N_4$ ceramics in a high-temperature and high-pressure water must be elucidated before they can be considered as components for nuclear power plants. In this study, the corrosion behaviors of $Si_3N_4$ ceramics containing MgO and $Al_2O_3$ as sintering aids were investigated at a hydrothermal condition ($300^{\circ}C$, 9.0 MPa) in pure water and 35 ppm LiOH solution. The corrosion reactions were controlled by a diffusion of the reactive species and/or products through the corroded layer. The grain-boundary phase was preferentially corroded in pure water whereas the $Si_3N_4$ grain seemed to be corroded at a similar rate to the grain-boundary phase in LiOH solution. Flexural strengths of the $Si_3N_4$ ceramics were significantly degraded due to the corrosion reaction. Results of this study imply that a variation of the sintering aids and/or a control (e.g., crystallization) of the grain-boundary phase are necessary to increase the corrosion resistance of $Si_3N_4$ ceramics in a high-temperature water.

• MISULJARYO - National Museum of Korea Art Journal
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• v.98
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• pp.200-225
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• 2020

This paper, based on "Minhwa Chaekgeori" paintings from the collection of the National Museum of Korea, identifies and discusses fourteen similar works in domestic and international collections as products of the Seokdang workshop. First, the relevant paintings are identified as products of the workshop known as Seokdang (石堂, literally "stone hall") by the workshop's seal that is stamped on them. Second, analysis of the iconography indicates that the paintings were likely produced in the 1920s. Third, research on certain geographic names and addresses associated with this group of paintings suggests that they might not have been separately commissioned, but are rather examples of partially "ready-made" paintings. Fourth, the paper discusses how the designs of various cultural products in these paintings reflects contemporaneous changes in Korea's diplomatic and commercial relations, i.e., the decline of relations with China and rise of relations with the United States and Europe. Finally, a comparison of the Seokdang chaekgeori paintings with the popular chaekgeori paintings produced by Yi Hyeongrok and Yi Deokyeong in the early twentieth century provides important implications for the succession of tradition and innovation in visual culture.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.694-697
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• 2005

The design of experiments are used for optimal design of formed tools to machine automobile bearing rubber seal die, which is classified into the high precision rubber mold. The clearance angle, rake angle and the length cutting edge are considered as the factors. The cutting force is selected to be a characteristic value and compared with the mean tool wear and life by repeated experiments. The design of the experiment is based on the repeated one-way factorial design, which finds the significance of the factors and the best level to predict the tool life by using ANOVA and regression.

• Proceedings of the Korea Institutes of Information Security and Cryptology Conference
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• 2006.06a
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• pp.373-376
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• 2006

전자봉인 장치는 능동형 RFID 장치로서, 화물 컨테이너의 문에 설치되어 컨테이너가 정당한 사용자가 아닌 다른 사용자가 개봉하였다는 사실을 인지하도록 하는 역할을 하는 장치이다. 전자 봉인장치는 RFID를 이용하므로 허용된 사용자 외에는 그 정보를 식별 할 수 없도록 할 필요가 있으며, 오랜 시간 고정된 장소에 존재하기 때문에 물리적으로 공격당하여 컨테이너의 내용물을 훔치거나 다른 물건으로 바꾸어 넣은 후 기존의 봉인의 내용을 복사한 새로운 봉인을 설치함으로서 봉인이 깨졌었다는 사실을 인지하지 못하도록 만드는 일을 막을 수 있어야만 한다. 본 논문에서는 리더와 태그가 통신하는 그 내용을 제 삼자가 인식하지 못하도록 함과 동시에, 봉인의 내용을 복사하더라도 원래 봉인을 대체할 수 없도록 하는 방법에 대해 제안 하고자 한다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2001.05a
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• pp.239-244
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• 2001

Hot hydrostatic extruder was developed. The main objective of the development is forming fine wire and tube. On account of effectiveness and high performance, the extruder was designed to have double action. Therefore the main cylinder and mandrel can be driven independently. To cope with severe condition of high temperature and pressure, wire-wound container equipped with heater was used. Sealing technique also is important in this process, so seal ring was made of super-elastic metal. Another key for successful forming is choice of proper pressure medium. Fine wire and tube produced by the extruder can be used in semiconductor industry and medicine.

• Proceedings of the Korean Information Science Society Conference
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• 2012.06d
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• pp.424-426
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• 2012

컨테이너 보안장치는 컨테이너 문에 부착하여, 문의 개폐 여부를 전자적 신호를 통해 수집하는 장치이다. 이와 관련하여 국제표준화기구의 ISO18185를 통해서 관련 내용이 다루어진다. ISO18185를 기반으로 여러 업체에서 다양한 컨테이너 보안장치를 제조하고 있으며, 대표적으로 savi사의 e-Seal이 있다. 표준에서 제시한 CSD는 리더를 통해 통신하여 상위 프로그램에게 정보를 제공한다. 그러나 이는 리더가 없는 지점에서는 CSD의 정보를 알 수 없다는 단점이 있다. 그래서 WCDMA 통신을 통해 주기적으로 자신의 상태를 보고하는 CSD가 개발중이며 본 논문은 주기적으로 자신의 정보를 전송하는 WCDMA기반 CSD와 리더기반 CSD를 동시에 지원하는 플랫폼 설계 및 구현을 다루고 있다.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.30 no.4
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• pp.30-38
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• 2007

In this study, we propose an RFID based container terminal operation process. Field tests are conducted for 900 MHz (truck identification) tag and 433 MHz RFID (container identification/e-seal) tag at an Incheon container terminal to verify possibility of applying RFID in the container terminal gate. To evaluate effect of applying RFID in the container terminal operation, simulation models for current and RFID based container terminals are developed using ARENA. Simulations are carried out using industrial field data and the result indicates that performance of the container terminal can be prominently improved after RFID application.

• Information and Communications Magazine
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• v.24 no.11
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• pp.43-50
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• 2007

RFID 기술은 유비쿼터스 사회로 가는 첫걸음으로 인식되면서 많은 연구와 활용방안이 논의되고 있다. 항만 물류의 화물 컨테이너 보호 분야도 그 좋은 예이다. 즉, 화물 컨테이너를 안전하게 잠그고 열며, 화물 정보를 보호하기 위한 전기적 잠금 장치로써 RFID 기술이 활용될 수 있다. 본 고에서는 화물 컨테이너 운송의 안전성을 지원하기 위한 국제 표준화 현황을 살펴보고, 실제 상용화에 박차를 가하고 있는 대표적인 RFID 장치인 전자봉인(eSeal)과 컨테이너 보안장치(CSD)의 기술적 특징에 관하여 논한다. 본 고에서의 주요 관심은 전자 장치로서의 화물 컨테이너 보호용 RFID 태그와 리더 기술이며, 특히 화물 컨테이너의 중요 데이터를 보호하여 컨테이너 운송 시스템의 효율성과 보안성을 동시에 향상시킬 수 있는 데이터 보호 요구사항을 정리하며 결론을 맺는다.