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최찬웅,진지원,이학성,허몽영,강기원 한국섬유공학회 2019 Fibers and polymers Vol.20 No.5
This study aims to optimize the polymerization conditions in a thermoplastic-resin transfer molding (T-RTM)process for the mechanical properties of carbon fiber-reinforced PA6 composites (CFPA6) using a response surface method. For this, a T-RTM process was first established with carbon fiber and caprolactam (PA6 monomer) as the base materials. Next, the injection speed, C20 (activator) rate, and C10 (catalyst) rate were selected as design variables that affect themechanical properties of the CFPA6 composites. Experimental conditions for the three design variables were establishedusing the central composite design (CCD) from the design of experiments (DOE) method. The significance of the CCD wasverified by analysis of variance (ANOVA) and sensitivity analysis. Finally, an optimization problem was solved with anobjective function of tensile strength and a constraint of the polymer conversion rate to identify the optimal CFPA6polymerization reaction conditions.
식품첨가물의 독성자료 고찰과 ADI 평가지침 - 소포제 Polydimethylsiloxane를 사례로-
최찬웅,정지윤,박형수,문진현,이광호,이효민 한국식품위생안전성학회 2009 한국식품위생안전성학회지 Vol.24 No.4
The purpose of this study was to introduce the toxicological study review to evaluate the safety of PDMS on the 69th JECFA meeting. Polydimethylsiloxane is a polymer and its ADI was established at 23rd JECFA meeting in 1979. The ADI was maintained although the specification was expanded at its 26th, 29 th, 37 th meetings. Recently, it was reported that PDMS with low molecular weight and viscosity has high absorption rate and different toxicity, so it was submitted at 69th meeting. Toxicological studies of PDMS were submitted from the sponsor and additional information is collected from a document searching. The toxicological studies were reviewed in accordance with the 'Guidelines for the preparation of toxicological working papers for the Joint FAO/WHO Expert Committee on Food Additives'. In the available acute, sub-chronic and chronic toxicity studies on PDMS, dose-related increases in incidence and severity of ocular lesions(corneal crystal, inflammation of the corneal epithelium etc.) were consistently observed after oral dosing. It seems to be a local irritant effect, but the mechanism by which the ocular lesions arose is unclear, although the lack of absorption of PDMS indicates that it is unlikely to be a direct systemic effect. Consequently, the relevance of the ocular lesions for food use of PDMS could not be determined. The ADI of PDMS was re-established from 0-1.5 mg/kg bw/day to 0-0.8 mg/kg bw/day by applying additional safety factor 2 based on its ocular toxicity. The result of 0-0.8 mg/kg bw/day is a temporary ADI until further data are provided to 2010.
국내 지역별 일사량을 고려한 버스 탑재형 태양광 패널의 발전량 예측
최찬웅,장병춘,곽민주,진지원 한국기계기술학회 2023 한국기계기술학회지 Vol.25 No.3
Numerous studies have attempted to predict the energy output of solar-powered vehicles based on different parameters such as road conditions, driver characteristics, and weather. However, since these studies were conducted on stationary vehicles, they are limited in their accuracy when applied to driving vehicles. This study aimed to improve the accuracy of electric power prediction for a solar-powered bus by applying a technique that improves energy efficiency without affecting driving performance. A comparative analysis of power generation and solar irradiance data was conducted for the bus driven on different roads to forecast its power generation, and a high-accuracy power generation prediction equation was derived. A comparison with actual test results revealed that a power generation forecast accuracy of at least 90% was achieved, validating the equation used for forecasting. With this power generation prediction process, it is possible to forecast the amount of energy generated in advance when a solar bus is operated in a specific area.
국내역학조사에 기초한 한국인의 카드뮴 PTWI 설정 연구
최찬웅,문진현,박형수,염태경,이광호,이효민 한국식품위생안전성학회 2009 한국식품위생안전성학회지 Vol.24 No.4
There are differences of Cadmium (Cd) urinary concentration which is considered as indicator of renal tubular dysfunction in other countries, so we have reviewed domestic epidemiological data and suggested Korean health based guidance value (HBGV) for Cd to improve an efficiency of risk management. We decided to apply the WHO calculation model which considered the relationship between dietary intake and Cd concentration in urine sample. It is determined that Cd concentration 2.5 ug/g creatinine in urine as the prevalence of renal tubular dysfunction based on epidemiological data, because there is no renal tubular dysfunction and injury/lesion such as proteinuria at the concentration of 11.63 ug/g creatinine which is the highest Cd concentration in urine from the domestic epidemiological data. It is identified that the ratio between the Cd dietary consumption (8.3~10.4 ug/day) and Cd urinary concentration (0.38 ug/g creatinine) in Korean adult who predicting never been exposed to Cd are 21.8~27.3 and then it is applied to the corresponding model suggested by WHO. Also it is applied that 10% of bioavailability and 50% of excretion rate of absorbed to body (the ratio is 24) were assumed. The estimate of daily Cd consumption level which begins tubular dysfunction is 1 ug/kg bw/day, so we suggest the Korean provisional tolerable weekly intake (PTWI) as 7 ug/kg bw/week.
위해인지도 맵을 이용한 나노기술 리스크 커뮤니케이션 연구
최찬웅(Chan-Woong Choi),정지윤(Ji-Yoon Jeong),황명실(Myung-Sil Hwang),정기경(Ki-Kyung Jung),이효민(Hyo-Min Lee),이광호(Kwang-Ho Lee) 환경독성보건학회 2010 환경독성보건학회지 Vol.25 No.3
Nanotechnology is the fastest growing area in scientific research and it has important applications in a wide variety of fields. Nevertheless, consumers encountered this new technology without any identification of risks and benefits. Also until now, there are no specific safety evaluation methods for nanotechnology. For this reason, we studied risk communication strategy for nanotechnology to prepare its application in commercialized products on public. A survey was conducted to identify the differences in perception between public (N=110) and expert (N=37) toward applied nanotechnology in food, drugs and cosmetic products. The survey results were used to draw up a risk cognitive map which was introduced by Paul Slovic, and the perception level of public and expert on nanotechnology was evaluated. As a result of the survey, public recognized nanotechnology as unknown but low dread risk factor, but expert recognized it as unknown and high dread risk factor. These results indicate that there are perception differences between two groups. Several risk communication strategies are reported including care, consensus and risk communication. In the case of nanotechnology, it contains both risks and benefits. Considering the nature of nanotechnology, the consensus communication which informs consumers about risks and benefits of issues is the most appropriate strategy.
Steel/CFRP 이종소재의 표면거칠기에 따른 접합특성 분석에 관한 연구
최찬웅(Chan-Woong Choi),전병욱(Byung-Wook Jeon),강기원(Ki-Weon Kang),진지원(Ji-Won Jin) 대한기계학회 2021 大韓機械學會論文集A Vol.45 No.11
본 논문에서는 steel/CFRP 이종소재의 표면거칠기에 따른 접합강도를 평가하고 분석하였다. 먼저 접합강도 산출을 위해 ASTM D3163에 따라 단일 겹침 전단 시편을 제조하였으며, 접착제의 접착두께를 선정하기 위해 접착두께 변화에 따른 접합강도를 산출하여 최적의 접착두께 0.3 mm를 도출하였다. 다음으로 steel 및 CFRP 소재에 적합한 표면거칠기 선정을 위해 표면거칠기에 따른 접합시험을 수행하였으며, steel 시편의 표면거칠기(Ra)는 1.0~2.0이고, CFRP 시편의 표면거칠기(Ra)는 1.2~2.0으로 적용하였다. 해당 조건을 이용해 접착두께가 0.3 mm인 접합시편을 제작하고 접합강도를 측정함으로 steel 및 CFRP에 적합한 표면거칠기를 선정하였다. 최종적으로 steel/steel, CFRP/CFRP 및 steel/CFRP 접합시편의 표면거칠기에 따른 접합 강도를 분석함으로 steel/CFRP 이종소재에 적합한 표면거칠기를 도출하였다. The bond strength according to the surface roughness of a steel/carbon-fiber-reinforced polymer (CFRP) multimaterial was evaluated and analyzed. First, we prepared a single-lap shear specimen to calculate the bonding strength and analyzed the bonding strength according to the change in the bonding thickness of the adhesive to derive the bonding thickness of 0.3 mm. Next, a bonding test was performed according to the surface roughness of steel and CFRP; the surface roughness (Ra) of the steel specimen was 1.0~2.0 and that of the CFRP specimen was 1.2~2.0. The surface roughness suitable for steel and CFRP was selected by manufacturing a bond specimen with an adhesive thickness of 0.3 mm and measuring the bond strength. Finally, we analyzed the bond strength according to the surface roughness of steel/steel, CFRP/CFRP and steel/CFRP bond specimens and derived the surface roughness suitable for steel/CFRP multimaterial.