• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.10
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• pp.1307-1313
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• 2011

The mechanical limited slip differential (LSD) in vehicles is being replaced by the electromagnetic LSD because of its fast response and better active control characteristics. The coil housing made of STS 304 is one of the most important parts in the solenoid assembly of the electromagnetic LSD. High geometrical accuracy is a prerequisite for the manufacture of such coil housings, but precision machining is difficult because of the use of STS 304 thin plate and the variance in machining variables. The aim of this study is to optimize the mean and variance of the shape accuracy in the coil housing by finding a robust solution for the machining process conditions. The mean and standard deviation of the jaw contact pressure, cutting speed, and feed rate are considered to be the major parameters for minimizing the geometrical mean and variance. The response surface model based on the second-order Taylor series is combined together to minimize the mean and variance of the shape accuracy of the coil housing.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.39-46
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• 2017

In this paper, a model updating procedure based on the response surface method combined with the multi-objective optimization was proposed and applied for updating of the FE models representing a low-rise reinforced concrete building before and after the seismic retrofit. The dynamic properties to be matched were obtained from vibration tests using a small shaker system. By varying the structural parameters according to the central composite design, analysis results from the initial FE model using a commercial software were collected and used to produce two regression functions each of which representing the errors in the natural frequencies and mode shapes. The two functions were used as the objective functions for multi-objective optimization. Final solution was determined by examining the Pareto solutions with one iteration. The parameters representing the stiffnesses of existing concrete, masonry, connection stiffness in expansion joint, new concrete, retrofitted members with steel section jacketing were selected and identified.

• Applied Chemistry for Engineering
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• v.29 no.6
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• pp.734-739
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• 2018

We successfully coated poly(3,4-ethylenedioxythiophene) : poly(styrene sulfonate) (PEDOT : PSS) on CVD graphene by adding poly(vinyl alcohol) (PVA) to PEDOT : PSS. Extensive studies on the wettability of coating solutions and electrical properties of formed films led us to conclude that PVA with 89% of the degree of saponification and the molecular weight of less than $100,000gmol^{-1}$ produced optimum results. Furthermore, the optimum content of PVA was found to be 5% of PEDOT : PSS by the solid weight. The film coated by PEDOT : PSS with PVA on CVD graphene displayed a conspicuous improvement in the surface roughness, adhesive property, bending durability and stability in resistance at $160^{\circ}C$, compared to those of using CVD graphene films.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.6
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• pp.1068-1073
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• 2004

Response surface methodology (RSM) was used to monitor characteristics of hot water extracts from Hericium erinaceus. A central composite design was applied to investigate the effects of independent variables, extraction temperature (X$_1$), sample ratio (X$_2$) and extraction time (X$_3$) on dependent variables such as soluble solid (Y$_1$), total phenols (Y$_2$), crude protein (Y$_3$) and electron donating ability (Y$_4$) of the extracts. As the sample ratio increased, the soluble solid content increased, while extraction temperature played a minor role. As a whole total phenols and crude protein contents increased with increasing the sample ratio. Electron donating ability increased in proportion to extraction temperature and sample ratio, which didn't increase at certain period. Then ranges of optimum extraction conditions for maximized physicochemical properties were 91.5∼96.5$^{\circ}C$ in extraction temperature and 3.5∼4.2 g/100 mL in sample ratio. Predicted values at the optimized conditions were coincident with experimental values.

• Applied Chemistry for Engineering
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• v.19 no.1
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• pp.37-44
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• 2008

The multi-layer PET film of ITO/ATO was prepared by a wet coating method to obtain the transparent film with a high conductance at low cost. ITO nano-particles were synthesized by a SAS method at 15 MPa and $50^{\circ}C$, where optimized rate of In/Sn was 65. Average diameter and resistivity of ITO obtained from SAS are $15{\pm}2nm$ and $4{\times}10^4{\Omega}{\cdot}cm$. Coating solution was prepared at pH 10. Roughness (Ra), resistivity, and transmissivity of ATO film on PET are 9 nm, $5.5{\times}10^6{\Omega}{\cdot}cm$, and 91%. The multi-layered film of ITO/ATO was obtained by solution including 0.1, 0.5, 1.0, and 2.0 ITO wt% on ATO layer. Roughness (Ra) of multi-layered film with 0.1, 0.5, 1.0, and 2.0 ITO wt% is 4, 10, 12, and 16 nm, respectively. Corresponding resistivity with an increasing ITO concentration is $3.7{\times}10^6$, $2.4{\times}10^6$, $8{\times}10^5$, and $2{\times}10^5{\Omega}{\cdot}cm$. Transmissivity of ITO/ATO film decreases as 89, 88, 86, and 82% with an increasing ITO concentration as 0.1, 0.5, 1.0, and 2.0 wt%.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.11
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• pp.205-210
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• 2014

This is concerned with the technology to display the design on Porcelain and adjust malfunction for moving effect and light intensity by curator. More precisely, the technology makes it possible that the porcelain is connected to Light module which is the device for controlling light emission and rotating rolling plate, etc that are connected to LED light module, optical fiber and controller that is for scenario from the given storytelling. In addition, with a WiFi portable device (Smart-phone, other mobile device). equipped with a scenario programs, information for operation, failure and malfunction can be obtained and analyzed in real-time, and menu color and alarm is alerted when the displaying design is in abnormal status, which makes the early reactions to the status. Furthermore, the collected data can be sent through WiFi network to the device and PC managed by the curator specialized in managing the design on the Porcelain, thus the technology could help the curator who have less knowledge about moving pattern on the Porcelain. There is always a possibility of malfunction due to various condition that are caused by wring-harness when modules are wired-connected. In this research, in order to overcome this problem, we propose a system configuration that can do monitoring and diagnosis with a device for collecting data from LED control module, Light emission sensor and a personal WiFi device. Also, we performed connection between optical Fiber and LED and interlock for the system defined by the definition for information and storytelling scenario.

• Journal of Life Science
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• v.31 no.8
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• pp.761-770
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• 2021

In this study, the optimal medium composition for enhancing protease production was established by the Bacillus strain isolated from Makgeolli, a traditional fermented food, using the response surface methodology. B. amyloliquefaciens SRCM115785 was selected as the protease producer by productivity analysis and identified by 16S rRNA gene sequencing. Plackett-Burman design (PBD) was introduced to analyze the effect of each component on protease production among the 11 selected medium components. As a result, glucose, yeast extract, and beef extract were finally selected as factors for enhancing protease production. Central composite design (CCD) analysis was designed as a method to determine the optimal concentration of each component for protease production and the concentration of each medium composition for maximum protease production was predicted to glucose 6.75 g/l, yeast extract 12.42 g/l and beef extract 17.48 g/l. The suitability of the experimental model was proved using ANOVA analysis and as a result of quantitative analysis to prove this, the amount of increase was 230.47% compared to the LB medium used as a control. Through this study, the optimization of medium composition for enhancing protease production was established, and based on this, it is expected that it can be efficient use of protease as an industrial enzyme.

• Proceedings of the KWS Conference
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• 2009.11a
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• pp.10-10
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• 2009

파이프 용접은 중력의 영향으로 인하여 위치에 따라 같은 용접변수라도 비드 형상이 매우 달라 지게 된다. 또한 지금까지 많은 용접 기술자들이 위험하고 까다로운 환경에서 수작업으로 용접을 실행하였다. 따라서 이러한 이유로 용접 자동화 공정이 반드시 필요하게 된다. 본 연구에서는 FCAW를 사용하여 파이프 모재 대신 필릿 평판을 아래보기, 위보기 자세를 포함하여 9개 자세에서 실행하였다. 용접 자세를 비롯한 용접 변수와 비드 형상 변수간의 관계를 비선형 회귀 분석과 구간적 3차 에르미트 보간법을 이용하여 주어진 용접 변수에서의 비드 단면의 형상을 예측하고, 비드의 결함 유무를 파악하였다. 이러한 방법을 통하여 자세에 따라서 용접 결함이 없는 용접 변수를 구할 수 있었다. 시각센서를 이용하여 용접 후 비드 형상에 대해 모니터링을 실시하였다. 모니터링의 알고리즘은 영상획득, 이진화, 세선화, 적응형 미디언 필터링, 적응형 허프 변환, 용접 결함 검출의 순서로 구성되어 있으며, 본 연구에서는 보다 빠른 영상처리를 위하여 적응형 미디언 필터링을 제시하였다. 모니터링을 통하여 2차원 비드 단면뿐만 아니라, 디루니 삼각법을 적용하여 3차원으로 비드 표면을 표현할 수 있다. 보간법을 사용하여 얻은 비드 형상과 시각 센서를 통하여 얻은 비드 형상간의 비교를 통하여 본 연구의 적합성 여부를 확인하였다.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.141-142
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• 2008

다결정 실리콘 박막 트랜지스터를 만들기 위해 가장 많이 사용되는 제작방법은 비정질 실리콘을 기판에 형성한 뒤 결정화 시키는 방법이다. 고온에서 장시간 열처리하는 고상 결정화(SPC)와 레이저를 이용한 결정화(ELA)가 자주 사용되어진다. 그러나 SPC의 경우는 고온에서 장시간 열처리하기 때문에 유리 기판이 변형될 수 있고 ELA의 경우 장비가격이 비싸고 표면일 불균일하다는 문제점이 있다. 본 연구에서는 이 문제를 해결하기 위해서 화학 기상 증착법(저온 공정)을 이용하여 비정질 실리콘 박막을 증착 시키고, 이를 금속 촉매를 이용하여 금속 유도 결정화 방법(MIC)으로 결정화 시키는 공정을 이용하였다. 유리 기판 상부에 버퍼 층을 형성한 후 플라즈마 화학 기상 증착법(PECVD)을 이용하여 비정질 실리콘을 증착하고 Ni-solution을 이용하여 얇게 Ni 코팅하고 그 시료를 약 $650^{\circ}C$의 Rapid Thermal Annealing(RTA) 공정을 이용하여 비정질 실리콘을 다결정 실리콘으로 결정화 시키는 연구를 진행하였다. Ni 코팅시간은 20분, RTA 공정은 5시간의 진행시간을 거쳐야 최적의 결정화 정도를 만들어낸다.

• Korean Journal of Food Science and Technology
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• v.48 no.2
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• pp.133-141
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• 2016

The physicochemical properties, antioxidant capacities, and sensory optimization of taro (Colocasia esculenta) under different aging conditions were investigated to develop black taro. Black taro was processed in three steps (steaming: $95{\pm}3^{\circ}C$ for 1 h; aging: 85, 90, $95^{\circ}C$ for 20, 40, and 60 h; drying: $60^{\circ}C$ for 24 h) and ground into a powder for all experiments. Black taro showed an increased crude fiber content and browning index compared to raw taro. Calcium oxalate contents, reducing sugar contents, moisture contents, and lightness values were decreased during the processing of taro. Improvements in total polyphenol content and antioxidant activity (DPPH, ABTS, FRAP) were observed in the black taro samples aged at higher temperature. Response surface methodology was used for sensory optimization, and the optimum aging conditions with the highest acceptance values were found to be $88.73^{\circ}C$ for 39.50 h for taste, and $88.82^{\circ}C$ for 42.60 h for overall acceptance.