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고성능 페트 생산용 폴리스티렌 기반 하이브리드형 나노구조체 생산
최재봉(Jae Bong Choi),김상희(Sanghee Kim) 대한기계학회 2014 大韓機械學會論文集B Vol.38 No.8
친환경 소재인 황토는 화장품, 건축물, 식·음료 저장용기 등의 제조에 이용된다. Polyethylene terephthalate(PET, 페트) 는 식·음료 저장용기로 널리 사용되고 있으나, 미세기공(~nm)이 존재하여 페트 내·외부 사이에 공기의 유동으로 음료수에 유통기한이 단축되는 문제점이 대두되고 있다. 본 연구의 목적은 황토-폴리스티렌 하이브리드 구조체를 제작하여 이를 페트에 적용시켜 유통기한의 연장을 꾀하고자 한다. 친수성 소재인 황토의 소수성 페트에 직접적용을 위해 매개체로 소수성 폴리스티렌을 이용하였다. 나노크기의 황토입자가 분산된 현탁액을 에멀젼 중합으로 나노크기의 폴리스티렌 입자 내부에 캡슐화 시켰다. 원활한 캡슐화 과정을 위해 에멀젼 중합 조건을 확립하였으며, 제작된 하이브리드 구조체의 형태 및 캡슐화 정도를 주사전자현미경, X-선 분광기, X-선 회절 분석기로 분석하였다. The ecofriendly yellow ocher is used in the manufacturing of cosmetics, construction, and food packaging. The polyethylene terephthalate (PET) used for manufacturing food containers has a microporous structure that causes aeration. Hydrophilic yellow ocher may be applied to hydrophobic PET by surface modification to overcome this issue. The aim of this study is to fabricate a yellow ocher polystyrene hybrid structure in the form of nanoparticles using an optimizing molar ratio of styrene, divinylbenzene, and potassium peroxodisulfate for use in emulsion polymerization. The polymerization was conducted in a yellow ocher suspension that was prepared by dispersing mechanically ground yellow ocher in DI water. The prepared hybrid structure was measured using scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The measurement revealed the spherical morphology and Si component that resulted from the yellow ocher in the polystyrene particles. We expect that this hybrid structure would be used as platform material to minimize aeration in PET.
최재봉(Jae Bong Choi),김상희(Sanghee Kim) 대한기계학회 2020 大韓機械學會論文集B Vol.44 No.4
현재 일반적으로 행해지는 계란의 신선도 선별은 침습적 방법에 기반하여 국내 하루 생산량인 1,000만 개를 대상으로 샘플링에 의해 0.01%의 계란을 선별하여 파란 후 계란 성분을 호우지수(Haugh unit)의 범위에 따라 신선란 판별의 기준으로 설정한다. 본 연구의 목적은 비침습적인 광학 측정 및 로드 셀 기반의 모듈을 개발하여 샘플링 법의 한계를 벗어나 생산 현장에서 수거되는 전체 회수란을 대상으로 선별의 정확도를 높이고자 한다. 이를 위해서 신선란에 대한 물성 및 광학적 특성을 측정하여 데이터 베이스를 구축하고 이를 기반으로 신선란에 대한 선별 값 다섯 단계를 기준으로 설정하였다. 생산현장에서 이용하는 이송 컨베이어부의 상부에 광학 측정 모듈을 컨베이어 벨트부에 로드 셀을 장착한 후 계란의 이송 중 측정되는 실시간 광학 및 물성 데이터를 전송 받고 이를 선별 값에 할당 시켜 실시간으로 계란의 등급별 선별이 가능하도록 하였다. Generally, the grading or sorting of fresh eggs is based on the invasive Haugh unit (HU) measurement of selected eggs by sampling from a larger population of daily production. HU determines the egg protein quality based on the height of egg white (albumen) separated from the cracked eggshell. The aim of this study is the implementation of a non-invasive and on-site real-time detection and sorting system for the eggs produced daily. The detection module is composed of an optical sensor, load cell, and analyzing unit. The detection module collects data from the eggs at the beginning of the conveyor transportation. At the end of the transportation, the eggs are sorted as five different grades based on the assigned index. The analyzing unit communicates with a developed database to assign an index value by comparing the acquired real-time value with the records in the database, in which a wide range of optical and physical properties of the eggs are categorized as five different levels.
강동원(Dong-Won Kang),서정우(Jeong-Woo Seo),최진승(Jin-Seung Choi),최재봉(Jae-Bong Choi),탁계래(Gye-Rae Tack) 대한전기학회 2014 전기학회논문지 Vol.63 No.6
The purpose of this study was to extract accurate parameters of facial movement features using 3-D motion capture system in speech recognition technology through lip-reading. Instead of using the features obtained through traditional camera image, the 3-D motion system was used to obtain quantitative data for actual facial movements, and to analyze 11 variables that exhibit particular patterns such as nose, lip, jaw and cheek movements in monosyllable vocalizations. Fourteen subjects, all in 20s of age, were asked to vocalize 11 types of Korean vowel monosyllables for three times with 36 reflective markers on their faces. The obtained facial movement data were then calculated into 11 parameters and presented as patterns for each monosyllable vocalization. The parameter patterns were performed through learning and recognizing process for each monosyllable with speech recognition algorithms with Hidden Markov Model (HMM) and Viterbi algorithm. The accuracy rate of 11 monosyllables recognition was 97.2%, which suggests the possibility of voice recognition of Korean language through quantitative facial movement analysis.
유한요소법을 이용한 다양한 피질골 두께에서 6종의 골내임플랜트에 대한 수치적 연구
이용찬(Yong Chan Lee),조병욱(Byoung Ouck Cho),박영주(Young Ju Park),이영규(Young Kyoo Lee),최재봉(Jae Bong Choi),주원(Won Joo),최귀원(Kui Won Choi) 대한구강악안면외과학회 1999 대한구강악안면외과학회지 Vol.25 No.1
Dental implant is increasingly used to rehabilitate the masticatory function of missing teeth. Several types of dental implant have been desiened to give an optimal stress distribution to the surrounding bone, In this study, six types of implant were investigated using finite element methods 1) how the variation of cortical bone thickness affects the stress distribution in bony regions depending upon implant types, and 2) which type gives the best characteristics in the sense of stress distribution and stability. The hybrid-type implant with tapered cylinder and screw gave the optimum properties in view of stability and response due to variation of cortical bone thickness.
박승헌,최재봉 한국경영과학회 1994 韓國經營科學會誌 Vol.19 No.1
This study proposes a new procedure to find an initial solution to reduce the number of iterations of goal programming. The process of computing an initial solution is divided into two steps in this study. Decision variables which satisfy feasibility using Gaussian eliminations construct an initial solution reducing the iterations in the first step. It uses LHS as a tool that decision variables construct an initial solution. The initial solution which is constructed by the first step computes the updated coefficient of the objective function in the second step. If the solution does not satisfy the optimality, the optimal solution using the Modified Simplex Method is sought. The developed method doesn't reduce the overall computing time of goal programming problems, because time is more required for the process of constructing an initial solution. But The result of this study shows that the proposed procedure can reduce the large number of iterations in the first step effectively.