A Study on the Application of Skirt Plates on Jacket Support Structures of Offshore Wind Turbines

Choi, Byeong-Ryoel,Choi, Han-Sik,Jo, Hyo-Jae,Lee, Sang-Hyep,Park, Young-Ho Korean Society of Ocean Engineers 2018 Journal of advanced research in ocean engineering Vol.4 No.2

The Korea Offshore Wind Power (KOWP) is planning to construct offshore wind energy farms with an overall rated power of 2.5 GW in the south-western coast of the country until 2019. Various types of support structures for offshore wind turbines have been proposed in the past. Nevertheless, in South Korea, jacket structures have in general, been applied as support structures for offshore wind turbines owing to the many accumulated experiences and know-how regarding this kind of support structure. The choice of offshore structure is mainly influenced by site conditions such as seabed soil type and sea environment during installation. In installing jacket sets on the seabed, the mudmat is necessary to maintain the equilibrium of the jacket without the aid of additional devices. Hence, this study proposes the installation of skirt plates underneath the bottom frame of jackets in order to improve the installation stability of jacket structures under rougher sea conditions. To confirm the effect of skirt plates, installation stability analyses considering overturning, sliding and bearing capacity have been performed. From the results, it is shown that jacket structures with skirt plates can contribute to improving the sliding stability of the structures of new wind power farms, while providing economic benefits.

New Design for Jacket-type Offshore Wind Turbine Support Structure for Southwest Coast of South Korea

Choi, Byeong-Ryoel,Jo, Hyo-Jae,Choi, Han-Sik,Ha, Sung-Yeol,Park, Young-Ho Korean Society of Ocean Engineers 2017 Journal of advanced research in ocean engineering Vol.3 No.4

The Korea Offshore Wind Power (KWOP) cooperation is planning to construct offshore wind energy farms with an overall rated power of 2.5 GW along the southwestern coast by 2019. Hitherto, various structural types of support structures for offshore wind turbines have been being proposed, but these structures have lacked economic analysis studies. Therefore, their economical superiority to existing types has been difficult to guarantee. An offshore structure with economic efficiency will have a minimum amount of mobilizing equipment and short offshore construction period because of the application of rapid installation methods. Thus, the development of a new support structure with economic efficiency is generally considered to be necessary. Accordingly, this paper proposes a newly developed and more economical jacket type for the offshore support structure. This study confirmed its structural safety and performance by conducting a structural analysis and eigenvalue analysis. The manufacturing and installation costs were then estimated. As a result, the new jacket type of offshore support structure proposed in this study significantly reduced the manufacturing and installation costs. Therefore, it is expected that the proposed jacket will contribute to reducing construction expenses for new wind power farms and invigorating wind power farm businesses.

Temperature effects on development of Naranga aenescens Moore (Lepidoptera: Noctuidae)

Byeong-Ryoel Choi,Chang-Gyu Park,Sang-Guei Lee,Hong-Hyun Park,Jeong Joon Ahn 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.04

The rice green caterpillar Naranga aenescens Moore (Lepidoptera: Noctuidae) is one of important destructive insect pests to Poaceae including rice and corn. We investigated the development periods of N. aenescens egg, larva, pupa and total immature at eight constant temperatures of 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, and 32.5°C, respectively. N. aenescens developed successfully from egg to the adult stage at all temperatures tested except 15.0°C. Developmental rate of N. aenescens increased as temperature increased from 15.0 to 30.0°C but declined at 32.5°C except pupa stage. The lower developmental threshold (LDT) and thermal constant (K) was estimated by linear regression. Higher temperature threshold (TH) and lower temperature threshold (TL) were calculated by two nonlinear functions. LDT and K from egg to adult emergence were 12.01°C and 330.84DD. The temperature range of N. aenescens from TL to TH using performance model (24.03) was wider than that from SSI model (19.77). Developmental completion of N. aenescens was described using a two-parameter Weibull distribution model. The adult emergence frequency of N. aenescens over full range of constant temperatures was simulated using developmental rate functions and Weibull function.

Oviposition model of Naranga aenescens Moore (Lepidoptera: Noctuidae)

Byeong-Ryoel Choi,Hong Hyun Park,Chang-Gyu Park,Sang-Guei Lee,Jeong Joon Ahn 한국응용곤충학회 2015 한국응용곤충학회 학술대회논문집 Vol.2015 No.10

The longevity and fecundity of Naranga aenescens adult were investigated at temperatures of 15.0, 17.5, 20.0, 22.5, 25.0, 27.5, 30.0, and 32.5°C. Adult longevity was influenced by temperature but there was no temperature effect of fecundity. Longevity decreased with increasing temperature: it was highest at 15°C (22.2 ± 3.51 days) and lowest at 32.5°C (6.2 ± 0.32 days). Total fecundity was highest at 25°C (1693 eggs) and lowest at 15.0°C (1115 eggs). The oviposition period was longest at 20°C (8.8 ± 0.57 days) and shortest at 32.5°C (4.1 ± 0.21 days). The oviposition model presented in this study consisted of two reproductive components (total fecundity and age-specific oviposition rate) and a survival component (age-specific survival rate). The relationship between adult developmental rate and temperature was described by the Logan 6 model (r2=0.98, p<0.0001).The age-specific survival rate was explained by a exponential function (r2=0.98, p<0.00001). The age-specific cumulative oviposition rate was described by the two-parameter Weibull function (r2=0.95, p<0.00001). Temperature-dependent fecundity was estimated using the Briere-2 model (r2=0.91, p<0.0125). Daily egg production of N. aenescens in relation to adult age and temperature was estimated.

Thermal effects on development and fecundity of Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphididae) on barley

Byeong-Ryoel Choi,Chang Woo Ji,Bueyong Park,Chang-Gyu Park,Jeong-Hwan Kim,Jeong Joon Ahn 한국응용곤충학회 2016 한국응용곤충학회 학술대회논문집 Vol.2016 No.04

The bird cherry-oat aphid Rhopalosiphum padi (Linnaeus) (Hemiptera: Aphididae) is a polyphagous species and worldwide distribution. We investigated the development periods and survivorship of R. padi nymph, and longevity and fecundity of R. padi adult. The study was conducted at six constant temperatures of 10.0, 15.0, 20.0, 25, 30.0, and 32.5°C, respectively. R. padi developed successfully from nymph to adult stage at all temperatures tested. Developmental rate of R. padi increased as temperature increased from 10.0 to 25.0°C and declined after then. The lower developmental threshold (LDT) and thermal constant (K) of R. padi nymph stage were estimated by linear regression. Higher temperature threshold (TH) and lower temperature threshold (TL) were calculated by two nonlinear functions. LDT and K of R. padi nymph stage were 5.61°C and 100.65DD. The temperature range of R. padi from TL to TH using empirical model (32.18) was wider than that from biophysiological model (27.08). Developmental completion of R. padi nymph stage was described using a two-parameter Weibull distribution model. The adult emergence frequency of R. padi over full range of constant temperatures was simulated using developmental rate functions and Weibull function. Daily egg production of R. padi in relation to adult age and temperature was estimated. Life table parameters were estimated by the jackknife method.

항온조건에서 긴등기생파리 [Exorista japonica (Townsend)] (Diptera: Tachinidae) 온도별 발육

박창규,서보윤,최병렬,Park, Chang-Gyu,Seo, Bo Yoon,Choi, Byeong-Ryoel 한국응용곤충학회 2016 한국응용곤충학회지 Vol.55 No.4

야외에서 채집된 멸강나방(Mythimna separata) 유충 및 번데기로부터 우화한 기생파리를 NCBI 데이터베이스에 등록되어 있는 유전자 염기서열 정보(16S, 18S, 28S 그리고 CO I)와 비교하여 긴등기생파리(Exorista japonica)로 동정하였다. 긴등기생파리의 알부터 성충우화까지 발육 기간을 담배거세미나방(Spodoptera litura) 5~6령 유충을 숙주 곤충으로 하여 7개 항온조건(16, 19, 22, 25, 28, 31, $34{\pm}1^{\circ}C$)에서 조사하였고 온도에 따른 발육율과 발육완료 모델들의 매개변수들을 추정하였다. $34^{\circ}C$를 제외한 다른 항온 조건에서 알부터 성충우화까지 발육이 가능하였다. 알부터 번데기까지 발육 기간을 보면 $16^{\circ}C$(23.4일)에서 가장 길었고 $34^{\circ}C$(8.3일)에서 가장 짧았으나, 번데기부터 성충까지 발육기간은 $28^{\circ}C$(7.3일)에서 가장 짧았다. 알부터 성충우화까지 전체 발육 기간은 $31^{\circ}C$에서 16.3일로 가장 짧았고 $16^{\circ}C$에서 45.4일로 가장 길었으며 온도가 상승함에 따라 발육기간은 짧아졌다. 선형 발육율 모델을 이용하여 추정한 알부터 성충우화까지 발육영점온도와 유효적산온도는 각각 $7.8^{\circ}C$, 370.4DD 였다. 4개 비선형 발육율 모델(Briere 1, Lactin 2, Logan 6, Performance) 중에서는 Briere 1 모델($r^2_{adj}=0.96$)이 가장 높은 해석력을 보여주었다. 동일 연령 집단의 발육완료 분포를 설명하기 위해 사용된 3개 모델(2-parameter Weibull, 3-parameter-Weibull, Sigmoid)은 모두 같은 결정력($r^2_{adj}=0.90$)을 보였다. Exorista japonica is one of the major natural enemies of noctuid larvae, Mythimna separata and Spodoptera litura. The examined parasitoid was obtained from host species M. separata, collected at Gimje city and identified by DNA sequences (partial cytochrome oxidase I, 16S, 18S, and 28S). For purposed of this study, laboratory reared S. litura served as the host species for the development of the E. japonica. The developmental period of E. japonica immature stages were investigated at seven constant temperatures (16, 19, 22, 25, 28, 31, $34{\pm}1^{\circ}C$, RH 20~30%). Temperature-dependent developmental rates and development completion models were developed. E. japonica was successfully developed from egg to adult in $16{\sim}31^{\circ}C$ temperature regimes. Developmental duration was the shortest at $34^{\circ}C$ (8.3 days) and the longest at $16^{\circ}C$ (23.4 days) from egg to pupa development. Pupal development duration was the shortest at $28^{\circ}C$ (7.3 days). Total immature-stage development duration decreased with increasing temperature, and was the shortest at $31^{\circ}C$ (16.3 days) and the longest at $16^{\circ}C$ (45.4 days). The lower developmental threshold was $7.8^{\circ}C$ and thermal constant required to complete total immature-stage development was 370.4 degree days. Among four non-linear temperature-dependent developmental rate models, Briere 1 model had the highest adjusted R-squared (0.96). The distribution model of development completion for total immature stage development of E. japonica was well described by all model ($r^2_{adj}=0.90$) based on the standardized development duration. These results of study would be necessary not only to develop population dynamics model but also to understand fundamental biology of E. japonica.