• 한국CDE학회논문집
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• 제13권2호
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• pp.139-152
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• 2008

In order to survive worldwide competition, today's industries are experiencing strong pressure to introduce higher quality products with lower cost and shorter lead-time. Therefore, the role of design in the process of product development is increasing in significance. In this research, two methods for improving the design capability are proposed: construction of design environment and design automation using 3D CAD system. The designers and design process are the core of product design using 3D CAD system. In order to maximize the design performance, construction of the design environment including selection of a suitable system, designer training for best use of the system, establishment of an efficient design process, and stabilization of the environment are required. A method is suggested to construct design environment by systematizing the contents of the projects and consulting experiences carried out for various categories of business such as electronic devices, motorcycles, electricity parts, sanitary wares, injection molds, and die casing molds. Design automation helps reduce tedious and time-consuming jobs, simplify complicated and error-prone modeling and drawing works to shorten the lead time and improve the product quality. To develop a design automation system, understanding the process and the related knowledge on design are very important before implementing the system using API provided by 3D CAD system. In this research, an eight-step procedure is proposed for the development of a design automation system. These eight steps are analysis of needs, determination of specification, verification of specification using 3D CAD system, inspection of related API functions, programming, field test, application in practice, and maintenance. A case study in which five design automation systems in the design of turbine generators using the proposed method is introduced in detail. These systems play important roles in the generation of various output items including 3D models, drafts, material information, and NC data. The case study shows how effectively the design time is reduced and the quality improved using those systems.

• 한국세라믹학회지
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• 제52권5호
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• pp.299-303
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• 2015

The electrolyte is an important component in determining the performance of Fuel Cells. Especially, investigation of the conduction properties of electrolytes plays a key role in determining the performance of the electrolyte. The electrochemical properties of Yttrium stabilized zirconia (YSZ) were measured to allow the use of this material as an electrolyte for solid oxide fuel cells (SOFC) in the temperature range of $700-1000^{\circ}C$ and in $0.21{\leq}pO_2/atm{\leq}10^{-23}$. A Hebb-Wagner polarization experimental cell was optimally manufactured; here we discuss typical problems associated with making cells. The partial conductivities due to electrons and holes for 8YSZ, which is known as a superior oxygen conductor, were obtained using I-V characteristics based on the Hebb-Wagner polarization method. Activation energies for holes and electrons are $3.99{\pm}0.17eV$ and $1.70{\pm}0.06eV$ respectively. Further, we calculated the oxygen ion conductivity with electron, hole, and total conductivity, which was obtained by DC four probe conductivity measurements. The oxygen ion conductivity was dependent on the temperature; the activation energy was $0.80{\pm}0.10eV$. The electrolyte domain was determined from the top limit, bottom limit, and boundary (p=n) of the oxygen partial pressure. As a result, the electrolyte domain was widely presented in an extensive range of oxygen partial pressures and temperatures.

• Restorative Dentistry and Endodontics
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• 제45권3호
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• pp.31.1-31.20
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• 2020

Matrix metalloproteinases (MMPs) are enzymes that can degrade collagen in hybrid layer and reduce the longevity of adhesive restorations. As scientific understanding of the MMPs has advanced, useful strategies focusing on preventing these enzymes' actions by MMP inhibitors have quickly developed in many medical fields. However, in restorative dentistry, it is still not well established. This paper is an overview of the strategies to inhibit MMPs that can achieve a long-lasting material-tooth adhesion. Literature search was performed comprehensively using the electronic databases: PubMed, ScienceDirect and Scopus including articles from May 2007 to December 2019 and the main search terms were "matrix metalloproteinases", "collagen", and "dentin" and "hybrid layer". MMPs typical structure consists of several distinct domains. MMP inhibitors can be divided into 2 main groups: synthetic (synthetic-peptides, non-peptide molecules and compounds, tetracyclines, metallic ions, and others) and natural bioactive inhibitors mainly flavonoids. Selective inhibitors of MMPs promise to be the future for specific targeting of preventing dentin proteolysis. The knowledge about MMPs functionality should be considered to synthesize drugs capable to efficiently and selectively block MMPs chemical routes targeting their inactivation in order to overcome the current limitations of the therapeutic use of MMPs inhibitors, i.e., easy clinical application and long-lasting effect.

• Current Applied Physics
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• 제18권11호
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• pp.1338-1344
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• 2018

Band parameters and superconductivity of yttrium hypocarbide ($Y_2C$) have been investigated. The computations are performed using first-principles pseudopotential method within a generalized gradient approximation. The equilibrium lattice parameters have been determined and compared with experiment. Moreover, the material of interest is found to be stiffer for strains along the a-axis than those along the c-axis. A band-structure analysis of $Y_2C$ implied that the latter has a metallic character. The examination of Eliashberg Spectral Function indicates that Y-related phonon modes as well as C-related phonon modes are considerably involved in the progress of scattering of electrons. By integrating this function, the value of the average electron-phonon coupling parameter (${\lambda}$) is found to be 0.362 suggesting thus that $Y_2C$ is a weak coupling Bardeen-Copper-Schrieffer superconductor. The use of a reasonable value for the effective Coulomb repulsion parameter (${\mu}^*=0.10$) yielded a superconducting critical temperature $T_c$ of 0.59 K which is comparable with a previous theoretical value of 0.33 K. Upon compression (at pressure of 10 GPa) ${\lambda}$ and $T_c$ are increased to be 0.366 and 0.89 K, respectively, showing thus the pressure effect on the superconductivity in $Y_2C$. The spin-polarization calculations showed that the difference in the total energy between the magnetic and non-magnetic $Y_2C$ is weak.

• 정보보호학회논문지
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• 제31권4호
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• pp.853-862
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• 2021

오늘날 국가 기반시설의 전자적 침해 행위에 의한 정보통신 인프라의 교란 및 마비가 위협 요소로 대두되고 있다. 이에 정부는 주요 기반시설의 정보시스템 및 제어시스템을 보호하기 위해 주요정보통신기반시설 취약점 분석·평가제도를 정기적으로 시행하고 있으며 이를 효율적으로 운영하기 위해 매년 늘어난 인적·물적 자원을 투자하고 있다. 그러나 이러한 정부의 노력에도 불구하고 국가 기반시설을 대상으로 한 침해사고가 지속해서 발생함에 따라 정보보호 기반마련을 위한 정부의 자원 투입이 정보보호 활동 결과 산출에 미치는 영향도가 떨어져 평가체계가 효율적이지 못하다는 의문이 제기되고 있다. 따라서 본 연구에서는 주요정보통신기반시설 취약점 분석·평가 제도의 효율적 운용여부를 DEA 모형을 이용해 검토하고, 분석된 결과를 바탕으로 정보보호 수준 제고를 위한 개선방안을 제안하도록 한다.

• 마이크로전자및패키징학회지
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• 제31권1호
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• pp.23-28
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• 2024

유연소자를 이용한 전자제품은 실사용환경에서 가혹한 기계적 변형을 경험한다. 이에 따라 유연소자의 기계적 신뢰성에 대한 연구가 많은 연구자들의 관심을 받고 있다. 본 연구에서는 유연기판에 증착된 금속 박막의 최대 굽힘 변형률을 예측하기 위하여 기존에 사용하는 굽힘 변형률 모델과 유한요소해석을 이용하였다. 박막의 소재 및 두께, 기판의 두께를 달리하여 유한요소해석으로 굽힘 실험을 모사하였고, 기존 모델로 예측된 변형률과 해석결과를 서로 비교하였다. 굽힘 변형 시 박막 첨단과 주위의 변형률 분포를 확인하였고, 굽힘 정도에 따른 기존 모델의 오차율을 정리하였다. 신규수학적 모델을 제시하여 각 경우의 수에 따른 상수를 제시하였다.

• International Journal of Computer Science & Network Security
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• 제22권8호
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• pp.105-112
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• 2022

Innovation is considered as an implemented innovation in education - in the content, methods, techniques and forms of educational activity and personality education (methods, technologies), in the content and forms of organizing the management of the educational system, as well as in the organizational structure of educational institutions, in the means of training and education and in approaches to social services in education, distance and multimedia learning, which significantly increases the quality, efficiency and effectiveness of the educational process. The classification of currently known pedagogical technologies that are most often used in practice is shown. The basis of the innovative activity of a modern teacher is the formation of an innovative program-methodical complex in the discipline. Along with programmatic and content provision of disciplines, the use of informational tools and their didactic properties comes first. It combines technical capabilities - computer and video technology with live communication between the lecturer and the audience. In pedagogical innovation, the principles reflecting specific laws and regularities of the implementation of innovative processes are singled out. All principles are elements of a complex system of organization and management of innovative activities in the field of education and training. They closely interact with each other, which enhances the effect of each of them due to the synergistic effect. To improve innovative activities in the training of students, today computer technologies are widely used in pedagogy as a science, as well as directly in the practice of the pedagogical process. They have gained the most popularity in such activities as distance learning, online learning, assistance in the education management system, development of programs and virtual textbooks in various subjects, searching for information on the network for the educational process, computer testing of students' knowledge, creation of electronic libraries, formation of a unified scientific electronic environment, publication of virtual magazines and newspapers on pedagogical topics, teleconferences, expansion of international cooperation in the field of Internet education. The article considers computer technologies as the main building material for the entire society. In the modern world, there is a need to prepare a person for life in a multimedia environment. This process should be started as early as possible, because the child's contact with the media is present almost from the moment of his birth.

• 분석과학
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• 제21권4호
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• pp.284-295
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• 2008

플라스틱 시료 중 각종 유해물질 유무 확인을 위한 여러 가지 시험항목을 저비용으로 빠르게 분석할 수 있는 방법으로 Combustion ion chromatography(연소IC)를 사용한 방법을 채택하였다. F, Cl 및 Br의 3개 항목에 대하여 연소IC로 시험법 유효화 검증을 실시한 결과, 검량선은 0.5~4.0 mg/kg 농도범위에서 $r^2$ = 0.999~1.000의 상관관계 계수를 갖는 좋은 직선성을 나타내었으며, 검출한계는 0.005~0.024 mg/kg, 정량한계는 0.014~0.073 mg/kg 이였다. 인증표준물질(CRM)을 사용한 연소IC의 회수율은 95.5~104.9%이었다. 본 결과를 토대로 국내외 시험기관간 비교 숙련도 시험을 실시하였으며, 그 결과 연소IC 방법이 전기전자제품 중에 halogen-free 및 기타 유해물질 규제 대응을 위한 효율적인 분석방법임을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.143-148
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• 2001

PbWO$_4$ can be densified at 85$0^{\circ}C$ and it shows fairy good microwave dielectric properties; dielectric constant($\varepsilon$$_{r}$) of 21.5, quality factor(Q $\times$f$_{0}$) of 37,224 GHz, and temperature coefficient of resonant frequency($\tau$/suf f/) of -31ppm/$^{\circ}C$. Due to its low sintering temperature, PbWO$_4$ can be used as a multilayered chip component at microwave frequency with high electrical performance by using high conductive electrode metals such as Ag and Cu. However, in order to use this material for microwave communication devices, the $\tau$$_{f}$ of PbWO$_4$ must be stabilized to near zero with high Q$\times$f$_{0}$. In present study, PbWO$_4$ was modified by adding TiO$_2$, B$_2$O$_3$, and CuO in order to improve the microwave dielectric properties without increasing the sintering temperature. The addition of TiO$_2$ increased the $\tau$$_{f}$ and $\varepsilon$$_{r}$, due to its high rr(200ppm/$^{\circ}C$) and $\varepsilon$$_{r}$(100). However, the addition of TiO$_2$ reduced the Q$\times$f$_{0}$ value. When the mot ratio of PbWO$_4$ and TiO$_2$ was 0.913:7.087, near zero $\tau$$_{f}$(0.2ppm/$^{\circ}C$) was obtaibed with $\varepsilon$$_{r}$=22.3, and Q$\times$f/$_{0}$=21,443GHz. With this composition, various amount of B$_2$O$_3$ and CuO were added in order to improve the quality factor. The addition, of B$_2$O$_3$ decreased the $\varepsilon$$_{r}$. However, increased Q$\times$f$_{0}$ and $\tau$$_{f}$. When 2.5 wt% of B$_2$O$_3$ was added to the 0.913PbWO$_4$-0.087TiO$_2$ ceramic, $\tau$$_{f}$ =8.2, $\varepsilon$$_{r}$=20.3, Q$\times$f$_{0}$=54784 GHz. When CuO added to the 0.913PbWO$_4$-0.087TiO$_2$ ceramic, $\tau$$_{f}$ was continuously decreased. And $\varepsilon$$_{r}$ . and Q$\times$f$_{0}$ were increased up to 1.0 wt% then decreased. At 0.1 wt% of CuO addition, the 0.913PbWO$_4$-7.087Ti0$_2$ Ceramic Showed $\varepsilon$$_{r}$=23.5, $\tau$$_{f}$=4.4ppm/$^{\circ}C$, and Q$\times$f$_{0}$=32,932 GHz.> 0/=32,932 GHz.X>=32,932 GHz.> 0/=32,932 GHz.

• 한국산학기술학회논문지
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• 제17권6호
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• pp.750-758
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• 2016

일반적으로 시스템을 강성체로 설계할 경우 시스템의 구조적 안정성을 확보할 수 있으나 유리잔을 잡거나 작은 수술용 도구로 사용하는 등의 사용용도에 따라 활용성이 제한될 수 있다. 이러한 문제를 해결하기 위하여 유연한 재질을 사용하여 강성조절이 가능한 메커니즘에 대한 연구가 다양하게 이루어져 왔다. 기존에 연구했던 강성체와 연성체의 연속구조로 이루어진 모델에 텐던을 삽입한 구조를 이용한 가변강성 메커니즘을 통하여 가변강성 구조체에 대한 가능성을 확인하였다. 그러나 필요로 하는 가변강성을 충족하기 위한 구조체의 설계 변수에 대한 연구가 필요하였다. 따라서 본 연구에서는 가변강성 메커니즘의 다양한 변수 변화에 따른 강성변화 실험을 통해 강성의 경향성을 파악하고자 하였다. 실험 결과 지름이 클수록 강성은 증가하며 강성의 증가폭 또한 늘어난다. 또한 연성체 길이가 짧을수록 강성이 증가하며 텐던을 당겨 연성체를 압착할 경우 강성값은 비선형적으로 증가하였다. 동일 조건에서 연성체 길이변화에 따른 강성 증가폭과 강성체의 길이 변화에 따른 강성 증가폭을 비교하였을 때 연성체 길이 변화가 강성체 길이 변화 보다 강성값 변화에 영향을 미친다는 것을 확인하였다. 또한, 해석값이 실험값에 비하여 정확성은 낮지만, 가변강성의 경향성을 확인하기 위하여 해석적인 방법을 통한 강성을 예측해보았다. 이러한 변수변화 실험 결과는 필요로 하는 강성값을 충족하는 가변강성 메커니즘 설계에 활용할 수 있을 것이다.