• Transactions of the Korean Society of Mechanical Engineers
• /
• 제16권1호
• /
• pp.162-174
• /
• 1992

Blades are one of the critical parts of the wind machine. This paper presents a design procedure for the blade of a 7m diameter horizontal axis wind turbine with the constraint conditions of stresses and fundamental frequency. This blade consists of glass/polyester woven fabric and unidirectional prepreg. It was firstly designed by the classical beam theory on the assumption that torque box sustains all external loads and the reliability of the blade was then inspected in the preliminary estimation by using FEM.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 한국추진공학회 1997년도 제9회 학술강연회논문집
• /
• pp.15-15
• /
• 1997

본 연구는 전방점화 방식(the head-end ignition)을 채택하고 있는 composite 고체 추진기관(구룡 1모타)을 이용하여 후방점화 방식(the after-end ignition)에 의한 점화 가능성을 검토하였으며, 점화 방식 차이에 따른 추진기관의 초기 연소거동의 차이점을 고찰하고자 한 실험 연구로서, 후방 점화장치를 설계·제작하여 지상연소시험을 수행하였다. 점화장치는 착화장치(initiation system)와 에너지 방출장치(energy release system), 구조물(Hardware)로 구성되는데, 착화장치는 기존의 K2 squib를 사용하였고, 에너지 방출장치는 FRP튜브에 MTV pellet 점화제를 사용하였으며, 점화기를 후방에 부착시키는 방법으로는 flexible finger 형태의 locking sleeve를 설계하여 노즐목에 고정하였다.

• Food Science and Preservation
• /
• 제17권1호
• /
• pp.1-8
• /
• 2010

We investigated the effect of freezing on changes in the chemical components of semi-dried red pepper (SDRP). We used storage temperatures of $0^{\circ}C,\;-10^{\circ}C,\;-20^{\circ}C,\;and\;-70^{\circ}C$. After 30 days of storage, capsaicin content had decreased by 40% at $0^{\circ}C$ and by 21% at $-20^{\circ}C$. Initial vitamin C content was 1,358.02 mg%. Compared with control, the $0^{\circ}C$ storage group showed a significant decrease in vitamin C content but no such decrease was noted in the $-20^{\circ}C$ and $-70^{\circ}C$ storage groups after 30 days. ASTA values were not influenced by storage temperature or period, in agreement with previous results. We concluded that storage was effective at temperatures of less than $-20^{\circ}C$. Next, both dried red pepper (DRP) and SDRP were stored at $-20^{\circ}C$ for 12 months. DRP had the lower level of capsaicinoids (55.01 mg%) owing to the long drying time. After 12 months, SDRP capsaicinoid had decreased by 30-33%, compared with a decrease of 54% in DRP. Initial vitamin C contents were 721.48 and 955.25 mg% in DRP and SDRP, respectively, and, after 12 months, vitamin C loss in the SDRP group (37%) was less than that in fresh red pepper (FRP) samples (45%). Initial $\beta$-carotene content was greatest in the FRP group (259.82 mg%), and that of DRP decreased by 20% after 12 months. The color a/b value of SDRP (1.40) was greater than that of DRP (1.00).

• Proceedings of the Korean Aquaculture Society Conference
• /
• 한국양식학회 2003년도 추계학술발표대회 논문요약집
• /
• pp.64-64
• /
• 2003

대구 인공종묘 생산 기술 개발의 일환으로 수정란에 기생하여 폐사를 유발하는 세균 및 세균 감염 경로를 파악함으로써 수정란의 생존율과 부화율 향상을 위하여 본 실험을 실시하였다. 세균 감염 경로를 파악하기 위하여 난소와 정소 자체 세균 감염 여부를 조사하였다. 일반배지 (BHIA)와 비브리오 선택배지 (TCBS)를 사용하여 세균검사를 실시하였다. 난소의 세균 검사는 생식소 내부를 일부 절개한 후 멸균 roop를 찔러 세균을 검사하였고, 정소는 채정하기 전 복부를 절개하여 멸균 roop로서 적출하여 배지에 도말한 후 배양하였다. 수정란 내 세균 수는 수정란을 각각 20개씩 샘플하여 난 외부에 기생하는 세균을 제거하기 위하여 난소독제로 이용되고 있는 benzalkonium 0.1%로 1분간 소독한 후 멸균 생리식염수로 3회 세척하여 호모게나이즈하여 검사하였다. 호모게나이즈한 액 중 100${\mu}\ell$를 pipetting하여 일반배지(BHIA)에 도말하여 인큐베이터에서 배양하였다. 난소와 정소 내에서 세균이 검출됨에 따라 수정 시 세균 감염을 억제하기 위하여 자외선 살균해수와 일반해수를 수정액으로 사용하여 발생율을 비교 시험하였다. 수정 시간은 1분으로 동일하게 적용하였으며, 수정 용기는 멸균 처리된 일회용 100$m\ell$ 플라스틱 용기를 사용하였다. 수정 후 과다한 정자를 제거하기 위한 세란은 1$\ell$ 멸균 비이커에서 5회 30분 가량 실시하여 정자를 제거하였고 멸균 봉으로 저어주면서 수정란의 점착력을 제거하였다. 수정란은 100$\mu\textrm{m}$ 그물망으로 수정란 유실을 방지한 플라스틱 용기에 수용하여 유효수량 270$\ell$ FRP 수조에 수용하여 3$\ell$/min 환수하였고, 수온은 자연수온 1$^{\circ}C$로 유지하였다. 발생율은 만능투영기로 3회 측정하였다. 수정 후 세균과 기생충에 의한 수정란의 폐사를 억제하기 위하여 수정 직후, 수정 후 1일, 2일째 oxytetracycline과 iodine 처리에 따른 발생율 변화를 조사하였다. 발생율은 만능투영기로 조사하였고, 시험구별로 3회 측정하였다. 경과 일수별로 약제 처리는 약제 미처리 수정란 중 정상적인 발생이 이루어지고 있는 것을 선별하여 조사하였다. 약제 처리에 따른 배체 발생 단계는 수정 후 1일째는 상실기, 2일째는 포배기였다. 수정란 및 대구 자어에서 분리된 V. splendidus 에 의한 폐사를 예방하기 위해 in vivo에서 oxytetracycline 외 5종의 항생제를 대상으로 96well plate에서 최고 농도 250ppm부터 2 fold로 단계 희석하여 $25^{\circ}C$에서 48시간 배양하여 MIC를 조사하였다. 세균 감염경로 파악을 위하여 난소, 정소 및 정자에서 세균을 분리한 결과 일반배지 및 비브리오 선택배지에서 모두 균이 검출되었고, 균 동정 결과 터봇 자어에서 검출된 것으로 보고된(Gatesoupe et al., 1999) V. splendidus로 나타났다. 수정액과 정자 및 미수정란의 세균 분리 결과 일반배지에서 3$\times$10/ml ~ 7$\times$10/ml로 균이 검출되었다. 수정액을 일반해수와 자외선 살균 해수를 사용하여 발생율을 비교한 결과 수정 후 3일째 발생율은 자외선 살균해수 72.3%, 일반해수 52.7%였으며, 수정 후 7일째 40.9%와 25.1%로 자외선 살균해수가 유의적으로 높게 나타났다. 수정 후 경과 일수별로 oxytetracycline과 Iodine을 처리한 결과 수정 직후 처리한 시험구는 7일째 19.8%와 18.9%로 대조구 23.1%와 유의적인 차이가 없는 것으로 나타났다. 수정 후 1일째 처리한 시험구는 54.5%와 56.8%, 수정후 2일째 처리구는 47.9%와 50.6%로 두 시험구 모두 대조구와 수정 직후 처리구보다 유의적으로 높게 나타났다. 수정란 및 대구 자어에서 분리된 V. splendidus 에 의한 폐사를 예방하기 위해 in vivo에서 항생제 종류별 MIC 조사 결과 oxytetracycline이 0.48ppm으로 가장 효과가 높은 것으로 나타났다.

• Journal of the Korean Chemical Society
• /
• 제33권4호
• /
• pp.371-378
• /
• 1989

Kinetics of the substitution reaction of [pt[dien]X]$^+$(X = $Cl^-$, $Br^-$, $I^-$) with NO2- in aqueous solution were investigated by a spectrophotometric method at $20-35^{\circ}C$ and 1-1500 bars. The rates of these reactions were increased with raising temperature and pressure. The relative reactivities of replaceable ligands in [pt[dien]X]$^+$ follow the order ($Cl^-$ > $Br^-$ > $I^-$). Activation volumes (${\mid}{\Delta}V^{\neq}{\mid}$) were large negative values and decreased with raising temperature. First ($k_1$) and second($k_2$) order rate constants of these reactions were determined at $25^{\circ}C$ and both $k_1$ and $k_2$ were increased with raising pressure and activation volumes (${\Delta}{V_1}^{\neq}$, ${\Delta}{V_2}^{\neq}$) for the $k_1$ and $k_2$ path were large negative values respectively. The $k_1$ and $k_2$ of these reactions were determined at 1 bar and these values were increased with raising temperature. Activation parameters of $k_1$ and $k_2$ path were determined, therefore it can be inferred frp, these results that the substitution reactions of [pt[dien]X]$^+$ with ${NO_2}^-$ proceed through on associative (A) mechanism independent of a leaving groups and reaction paths.

• The Korean Journal of Malacology
• /
• 제20권2호
• /
• pp.121-124
• /
• 2004

Water temperature tolerance of spats of the Manila clam, Ruditapes philippinarum was investigated in the different temperature groups, 15, 20, 25, 30 and 35$^{\circ}C$. The survival rates of the groups were 99.7%, 91.0%, 88.7%, 73.3% and 0%, respectively (p < 0.05). When the temperature of the water decreased from 15$^{\circ}C$ to 5$^{\circ}C$, the survival of spats was higher than when the temperature increased. The growth and survival of spats were investigated in different types of bottom substrates in the tanks. The spats grew the best in the polyvinyl plates, the average shell length was 3.9 ${\pm}$ 0.4 mm. In the FRP tank bottom and sand bottom, the average shell lengths of spats were 3.6 ${\pm}$ 0.3 mm and 3.2 ${\pm}$ 0.3 mm, respectively. The best survival of spats cultured in the FRP tank bottom (22.9 g) and in the polyvinyl plates (20.6 g) (p < 0.05).

• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• 제7권2호
• /
• pp.161-170
• /
• 1997

This is an effort to confirm changes biological monitoring according to changes in levels of exposure to styrene for industrial workers. This study was conducted on 108 workers, including male of 64 and female 44 who were working at factories of FRP, dipping, and coating. An improved passive monitor method(organic vapor monitor; OVM) was employed to determine levels of exposure. The biological monitoring include blood styrene concentration, urinary mandelic acid(MA), and urinary phenylglyoxylic acid(PGA). Biological monitoring were made through the Collection of blood and urine. The mean value of exposure to styrene was 21.0ppm, which is measured by organic vapor monitor, one of improved passive monitors. The highest exposure level was observed among workers in boat factories, laminating procedure workers, processing workers, respectively(p<0.01). For exposure level, 11% of subjects under study showed over 50ppm which is time weighted average(TWA). The correlation coefficient between biological specimens and the exposure level was 0.62 for blood styrene concentration, 0.58 for MA corrected by creatinine, and 0.70 for PGA corrected by creatinine, respectively(p<0.01). The regression analyses found exposure level relative importance in explaining variance in biological monitoring. In additional to that, gender was a significant factor in explaining variance of MA and MA+PGA. Almost half of variance(49%) in blood styrene concentration was explained by predictors, including exposure level, age, gender, duration, and drinking volume during the last week(p<0.01). The very high correlation(higher than 0.95 was found when a comparison was made among three types of corrected methods, including uncorrected specific gravity and creatinine. In conclusion, these findings suggest OVM to represent levels of exposure to styrene for industrial workers. A discussion was made on possible use of specific gravity sample for biological monitoring. Exposure level may be predicted on MA, PGA in urine, which could be applied to represent biological monitoring.

• Journal of Ocean Engineering and Technology
• /
• 제28권1호
• /
• pp.77-84
• /
• 2014

Recently, CFRP composites have often been used as the materials for lightweight pleasure yacht hulls. Because CFRP composites not only make the hull light but also have good physical characteristics, in the leading countries of the marine industries, CFRP yachts are being sold at a higher price. The design and construction of FRP composite yachts, including those made of CFRP, have to follow rules based on ISO 12215, such as the hull structure rules of the international classification societies. On the other hand, there are no rules related to CFRP composites in the Guidance for Recreational Crafts, which was newly revised by the Korean Register of Shipping. In this paper, ISO 12215-5 and Part B, RINA Pleasure Yacht (REGISTRO ITALIANO NAVALE) on the design pressure and scantling of CFRP hull structures are compared and analyzed. Through a comparative study and the application to a cruise yacht design, we try to understand how to design CFRP hull structures using the international standards, ISO 12215, and the rules of the international classification society, RINA.

• Journal of Aquaculture
• /
• 제8권3호
• /
• pp.221-229
• /
• 1995

Two long term feeding trials using moist pellet diet were conducted to study the growth pattern of Korean rockfish (Sebastes schiegeli). Two groups of the fish with initially averaging of 6.8g and 11.0g were stocked in the indoor FRP tanks, and were fed with moist pellet for 22 months and 10 months, respectively. It took approximately 11 months and 23 months after parturition to grow up to 200g and 500g of average body weight, respectively. Average body weight of fish increased almost linearly, and no significant growth stagnation was observed even in winter (the lowest water temperature was $11^{\circ}C$) and summer (the highest water temperature was $25^{\circ}$) seasons. Growth rate, feed intake and protein intake decreased gradually with fish size up to approximately 200g of average body weight, and these values were remained relatively consistent afterward.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• 제40권4호
• /
• pp.344-350
• /
• 2004

This is the study on dry sliding wear behavior of unidirectional carbon fiber reinforced epoxy matrix composite at ambient temperature. The wear rates and friction coefficients against the stainless steel counterpart specularly processed were experimentally determined and the resulting wear mechanisms were microscopically observed. Three principal sliding directions relative to the dominant fiber orientation in the composite wear selected. When sliding took place against smooth and hard counterpart, the highest were resistance and the lowest friction coefficient were observed in the antiparallel direction. When the velocity between the composite and the counterpart went up, the wear rate increased. The fiber destruction and cracking caused fiber bending on the contact surface, which was discovered to be dominant wear mechanism.