Lost wax technique과 CAD를 이용한 pattern의 프린팅 방식으로 제작된 가철성 국소의치 금속구조물의 적합도 비교

최원준,우이형,김형섭,백장현,Choi, Wonjun,Woo, Yi-Hyung,Kim, Hyeong-Seob,Paek, Janghyun 대한치과보철학회 2018 대한치과보철학회지 Vol.56 No.1

가철성 국소의치의 금속구조물을 제작하는 방법은 왁스 패턴을 제작하여 주조하는 lost wax technique이 주로 사용되어 왔으나, 디지털 기술의 발달로 서베잉과 금속구조물을 CAD (Computer aided design)로 디자인하여 제작할 수 있게 되었다. 여러 증례에서 CAD를 이용한 pattern의 프린팅 방식으로 얻은 레진 패턴이 구강 내에 정확하게 적합 되었고 최종 금속구조물 또한 좋은 적합도를 보였다고 보고되었다. 본 원저는 치조골 소실이 심한 상, 하악부분 무치악 환자에서 가철성 국소의치의 금속구조물을 두 가지 방식으로 각각 제작하였다. 첫 번째는 일반적인 lost wax technique과 두 번째는 CAD를 통해 pattern을 프린팅하여 금속구조물을 주조하는 방식으로 제작하여, CAD data와 fit checker를 이용해 금속구조물과 서베이드 크라운과의 유격을 측정함으로써 금속구조물의 적합도를 비교하였다. 두 가지 방식 모두 임상적으로 사용 가능한 금속구조물의 적합도를 얻었기에 이를 보고하고자 한다. Lost wax technique of casting wax patterns has been used principally to make metal frameworks of removable partial dentures. Since the development of digital technology and CAD, metal frameworks can be built through digital surveying and framework designing. Many cases proved that resin patterns made by CAD printing method were well adapted to internal oral structure and final metal frameworks also showed good internal adaptation as well. The metal frameworks of a removable partial denture were made by both lost wax technique and CAD technique and were applied to a patient with severe alveolar bone loss. Using CAD data and fit checker, internal adaptation of both metal frameworks were evaluated by comparing the gap between surveyed crown and its structure. This study is to prove that metal frameworks by both techniques showed adaptation that can be applied in clinical field.

자동차 조립라인의 실시간 투입시스템의 자동화

최원준,박혜규,신현오,Choi, Won-Joon,Park, Hye-Kyou,Shin, Hyun-Oh 대한산업공학회 1996 산업공학 Vol.9 No.2

자동차 조립공장의 생산은 혼류생산 (Mixed-Model Production)의 대표적인 형태로서 동일한 조립라인에서 다양한 사양의 차량들을 Batch생산이 아니라 각 사양의 생산량이 평준화되도록 생산을 하는 것이 특징이다. 그런데 도장라인에서 생산완료 된 순서는 혼류조립라에서의 평준화 생산에 적합하지 않은 상태이므로 조립라인에의 투입순서를 재작성하여 제어하여야 한다. 본 논문에서는 조립라인의 실시간 투입순서 작성 및 운영시스템을 자동화하여 성공적으로 운영한 사례를 소개하고자 한다.

랜덤화된 트리워킹 알고리즘에서의 RFID 태그 보안을 위한 백워드 채널 보호 방식

최원준,노병희,유승화,오영철,Choi Wonjoon,Roh Byeong-hee,Yoo S. W.,Oh Young Cheol 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.5C

수동형 RFID 태그는 스스로 전력을 갖고 있지 않기 때문에 연산 능력이 매우 미약하고, 통신 신호는 크기가 약하고, 도달 거리가 짧다. 이런 특성을 이용하여, 대부분의 태그 보안 방법은 태그로부터 리더로 전달되는 무선경로인 백워드(Backward) 채널은 도청의 가능성이 거의 없다는 가정하에 리더로부터 태그로 정보를 전달하는 포워드(Forward) 채널을 보호하는데 초점을 맞추고 있다. 그러나, 실제로 태그와 가까이에 있는 불법적인 리더는 정보를 불법적으로 수집할 수 있다. 본 논문에서는 이러한 근접거리에서 백워드 채널을 보호할 수 있는 방법을 제안한다. 제안방법은 태그정보의 충돌방지를 위하여 제안된 트리워킹 방식의 도청가능성을 제거하기 위하여 제안된 랜덤화된 트리워킹과 같은 기존 방식들에서 문제점을 해결하여 준다. 제안 방법의 효율성은 분석 모델을 사용하여 보였으며, 표준 코드시스템인 EPCglobal, ISO, uCode의 경우 도청가능성을 거의 '0'에 근접시킴을 보였다. Passive RFID tag does not have its own power, so it has very poor computation abilities and it can deliver signals in very short range. From the facts, most RFID Tag security schemes assumed that the backward channel from tags to a reader is safe from eavesdropping. However, eavesdroppers near a tag can overhear message from a tag illegally. In this paper, we propose a method to protect the backward channel from eavesdropping by illegal readers. The proposed scheme can overcome the problems of conventional schemes such as randomized tree walking, which have been proposed to secure tag information in tree-walking algorithm as an anti-collision scheme for RFID tags. We showed the efficiency of our proposed method by using an analytical model, and it is also shown that the proposed method can provide the probability of eavesdropping in some standardized RFID tag system such as EPCglobal, ISO, uCode near to '0'.

자동차 조립공장의 일일 생산순서계획 시스템

최원준,Choi, Won-Joon 대한산업공학회 1996 산업공학 Vol.9 No.2

자동차 조립공장의 주요 공정은 차체라인, 도장라인, 조립라인의 순으로 구성되어 있다. 작업의 효율성을 높이기 위하여 차체라인과 조립라인은 주요 부품소모의 평준화를, 도장라인은 동일 색상차체의 연속 생산을 선호하므로, 생산순서의 결정시 상호 상층되는 점이 많다. 본 연구에서는 조립공장전체의 생산성을 극대화하기 위하여 차체라인, 도장라인, 조립라인의 특성을 고려한 일일생산순서결정 방법을 제시한다.

An optimal design of 4${\times}$4 optical matrix switch

최원준,홍성철,이석,김회종,이정일,강광남,조규만,Choi, Won-Jun,Hong, Song-Cheol,Lee, Seok,Kim, Hwe-Jong,Lee, Jung-Il,Kang, Kwang-Nham,Cho, Kyu-Man The Institute of Electronics and Information Engin 1995 전자공학회논문지-A Vol.32 No.8

The design procedure of a GaAs/AlGaAs semiconductor matrix optical switch is presented for a simplified tree architecture in the viewpoint of optical loss. A low loss, 0.537 dB/cm, pin type substrate is designed by considering the loss due to imputity doping at 1.3 $\mu$m wavelength. The operating voltage and the device length of a reversed ${\Delta}{\beta}$ electro-optic directional coupler(EODC) swith which is a cross-point device of the 4${\times}$4 matrix optical switch and the bending loss of rib waveguide are caculated as functions of waveguide parameters and bending parameters. There is an optimum bending radius for some waveguide parameters. It is recommened that higher optical confinement conditions such as wide waveguide width and higher rib-height should be chosen for structural parameters of a low loss and a process insensitive 4${\times}$4 matris optical switch. A 4${\times}$4 optical matrix switch which has a 3 dB loss and a 12 volt operating voltage is designed.

란타넘 산화물의 분산을 통해 향상된 파괴인성을 갖는 몰리브데넘 합금의 제조

최원준,박천웅,박정효,김영도,변종민,Choi, Won June,Park, Chun Woong,Park, Jung Hyo,Kim, Young Do,Byun, Jongmin 한국분말재료학회 (*구 분말야금학회) 2019 한국분말재료학회지 (KPMI) Vol.26 No.3

In this study, lanthanum oxide ($La_2O_3$) dispersed molybdenum ($Mo-La_2O_3$) alloys are fabricated using lanthanum nitrate solution and nanosized Mo particles produced by hydrogen reduction of molybdenum oxide. The effect of $La_2O_3$ dispersion in a Mo matrix on the fracture toughness at room temperature is demonstrated through the formation behavior of $La_2O_3$ from the precursor and three-point bending test using a single-edge notched bend specimen. The relative density of the $Mo-0.3La_2O_3$ specimen sintered by pressureless sintering is approximately 99%, and $La_2O_3$ with a size of hundreds of nanometers is uniformly distributed in the Mo matrix. It is also confirmed that the fracture toughness is $19.46MPa{\cdot}m^{1/2}$, an improvement of approximately 40% over the fracture toughness of $13.50MPa{\cdot}m^{1/2}$ on a pure-Mo specimen without $La_2O_3$, and this difference in the fracture toughness occurs because of the changes in fracture mode of the Mo matrix caused by the dispersion of $La_2O_3$.

제주 남서부지역 스코리아의 철 화합물에 대한 미시적 연구

최원준,고정대,Choi, Won-Jun,Ko, Jeong-Dae 한국재료학회 2008 한국재료학회지 Vol.18 No.3

Fe compounds in scoria as distributed in the south-western area of Jeju Island were investigated using X-ray fluorescence spectroscopy, X-ray diffractometry, and $^{57}Fe$ $M{\ddot{o}}ssbauer$ spectroscopy. The samples were prepared from four parasite volcanoes. It was found that these samples are typical basalt comprised of $SiO_2$, $Al_2O_3$, Fe, and silicate minerals. The $M{\ddot{o}}ssbauer$ spectra showed doublets for olivine, pyroxene, and ilmenite as well as sextets for hematite and magnetite. The valence state of Fe is chiefly a 3+ charge state with a slight 2+ charge state. It is expected that these results will add to the body of information related to the formation mechanisms of Jeju Island.

탄화 규소가 균일 분산된 규화 몰리브데넘계 복합재의 제조

최원준,박천웅,김영도,변종민,Choi, Won June,Park, Chun Woong,Kim, Young Do,Byun, Jong Min 한국분말야금학회 2018 한국분말재료학회지 (KPMI) Vol.25 No.5

Molybdenum silicide has gained interest for high temperature structural applications. However, poor fracture toughness at room temperatures and low creep resistance at elevated temperatures have hindered its practical applications. This study uses a novel powder metallurgical approach applied to uniformly mixed molybdenum silicide-based composites with silicon carbide. The degree of powder mixing with different ball milling time is also demonstrated by Voronoi diagrams. Core-shell composite powder with Mo nanoparticles as the shell and ${\beta}-SiC$ as the core is prepared via chemical vapor transport. Using this prepared core-shell composite powder, the molybdenum silicide-based composites with uniformly dispersed ${\beta}-SiC$ are fabricated using pressureless sintering. The relative density of the specimens sintered at $1500^{\circ}C$ for 10 h is 97.1%, which is similar to pressure sintering owing to improved sinterability using Mo nanoparticles.

Spectral Response Change in a Quantum Well Infrared Photodetector by Using Quantum Well Intermixing

최원준,김은규,H. J. Kim,한일기,J. C. Shin,J. I. Lee,J. W. Choi,Y. J. Park 한국물리학회 2003 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.42 No.III

We have studied the change of spectral response in a Quantum Well Infrared Photodetector (QWIP) by using the Impurity Free Vacancy Disordering (IFVD) technique to change the bandgap of GaAs/AlGaAs Multi Quantum-Well (MQW) absorption layer. The fabricated QWIP whose MQW absorption region was intermixed by an IFVD technique showed the maximum change in spectral response peak from 8 to 10mm at 10K when compared to a QWIP without intermixing.

글루타민산나트륨(Mono Sodium Glutamate)을 처방한 모발 경화제가 펌에 미치는 효과

최원준ㆍ유세은(Won Joon ChoiㆍSe Eun Yoo) 한국인체미용예술학회 2016 한국인체미용예술학회지 Vol.17 No.1

This study attempted to assess the applicability of the hair-hardener considering hair elasticity and retention through analysis of changes in hair conditions after chemical treatment. For this, the following were analyzed: safety and stability of the hair-hardener, changes in hair thickness, amino acid, changes in surface color, hair surface using the SEM, changes in tensile strength, and wave efficiency by the frequency of shampooing. Then, the results found the following: The stability of the hair-hardener was confirmed because there were no changes in its physical properties and color at room temperature and constant temperature. In a clinical allergy test as well, a negative response was found in all 20 clinical trial participants, which confirms its safety. In terms of changes in hair thickness, hair was thicker in the group that used the hair hardener than in the control group. In comparison of amino acid, total amino acid, L-glutamic acid, and cysteine contents increased in the experimental group that used the hair hardener. In terms of changes in surface color, L* value was high in the experimental group. A* value, which represents the level of reddish color, was also high in the experimental group. In contrast, b* value, which reveals the level of yellow color, was low in the experimental group. In observation of hair surface using the SEM, hair cuticles were tidier in the experimental group than in the control group. In terms of tensile strength, the experimental group was greater than the control group. According to measurement of wave efficiency by the frequency of shampooing after a general perm and setting perm as well, wave formation was more efficient in the experimental group.