구조물에 작용하는 바람하중을 정량적으로 예측하는 것을 거의 불가능하다. 그러나 그 하중이 백색잡음으로부터 재생될 수 있다는 가정은 동적해석을 위한 수치시뮬레이션에 매우 유용할 뿐만 아니라 역해석과정에서 바람하중에 대한 유일 해를 추정할 수 있 는 가능성을 높일 수 있는 추가적인 구속조건을 제공한다는 측면에서 매우 유리하다. 그러한 가정에 의하여, 구조물 응답에 영향을 미 치는 동적특성과 하중특성(하중모델)을 차례로 제거하고 나면 순수한 백색잡음만 남게 되므로 이러한 백색화과정을 통하여 구조물의 동적 특성과 하중특성을 동시에 추정할 수 있는 방안을 모색할 수 있을 것이다. 본 연구에서는 스펙트럼 백색화과정을 통하여 구조물 의 모달 파라미터와 모달하중(하중모델을 구성하는 파라미터)을 동시에 추정하는 새로운 역해석 기법을 제안한다. 백색화과정을 모달 응답에 적용하여 모달 파라미터과 하중모델 파라미터를 구하는 과정을 유도하였으며, 제안된 동시 추정기법을 단자유도 모형, 공탄성 모델에 대한 풍동실험에 적용하여 모달파라미터 특히 감쇠비추정의 신뢰성을 검증하였으며, 그 결과 신뢰도가 높은 모달 파라미터, 하 중모델 파라미터 추정이 가능함을 알 수 있었다.

고밀도폴리에틸렌(HDPE)은 대표적인 열가소성 플라스틱으로서 재활용성, 내충격성 등이 우수하여 차세대 친환경 소형선박용 재료로 각광받고 있다. 그러나, HDPE의 열변형온도는 하절기의 선체 온도와 비슷한 수준이며, 재료의 열팽창 특성으로 인해 선박 구조용 재료로서의 적용 가능성에 대한 기술적 검토가 필요하다. 본 연구에서는 선박이 일상적으로 겪을 수 있는 상온 이상 온도범위에서 HDPE 의 기계적·열적 물성치를 도출하였고, 모의설계한 HDPE 어선을 대상으로 연중 태양복사열과 기관실 내부 온도가 가장 높은 하절기 운용 상황을 모사한 열전달 해석을 통해 구조부재들의 온도변화 및 분포, 응력 및 변위 구배 등을 확인하고자 하였다. 혹서기의 높은 기온과 강한 태양복사에 노출되는 HDPE 선체의 온도는 재료의 열변형온도 수준까지 상승하며 열팽창에 의한 변형 및 국부응력을 보여 설계 및 검토단계에서 선체 변형을 고려할 필요가 있고 향후 선체변형 대응방안 및 구조안전성 평가기준 마련 시 온도상승에 따른 물성치 변화를 고려할 필요가 있다.

This study analyzed the correlation between carcass traits of Hanwoo steers and feeding methods (concentrate feed and total mixed ration for ruminants). The results indicated that in the feeding system using concentrate feed, the variation in carcass weight and marbling score among individual animals within farms tended to affect the average carcass sale price, with both showing negative effects (p=0.057, p=0.053). The standardized regression coefficients were used to compare the influence of each variable, revealing that the coefficients for carcass weight variation and marbling score variation were –0.38 and –0.30, respectively, indicating a greater influence of carcass weight variation. Therefore, reducing the variations in carcass weight and marbling score among steers in farms using concentrate feed is likely to increase the average carcass sale price. In the case of farms using total mixed ration (TMR) for ruminants, the variation in marbling score among individual animals significantly affected the average carcass sale price, showing a negative effect (p=0.002). Thus, reducing the variation in marbling score among steers in TMR farms is likely to increase the average carcass sale price. In summary, the coefficient of variation of marbling score was found to have a significant impact on the average carcass sale price of the farm. In farms using concentrate feed, the variations in both carcass weight and marbling score tended to affect the average carcass sale price (0.05<p<0.1). Meanwhile, in farms using TMR, the variation in marbling score had a significant impact. In conclusion, the coefficient of variation for marbling score in carcass performance was found to have the most significant impact on the average carcass sale price for both feeding types (concentrate and TMR diets). Furthermore, reducing the variation along with carcass weight of Hanwoo steers on concentrate feed may be a way to increase farm income.

We analyzed risk factors of coastal gillnet fishers during fishing process and considered work safety measures to reduce safety accidents during fishing using a UWB (ultra wideband) based positioning system. The static position accuracy of the UWB based positioning system was 45 cm. When entering a port, there is a risk of falling overboard. When casting a net, there was a risk of falling overboard due to being hit by fishing gear or guards, or getting caught in a buoy line or sinker line. When hauling a net, there is a risk of getting caught between fishing gear and net hauler, and the risk of musculoskeletal disorders due to repetitive work over a long period of time. Most safety accidents during work on fishing boats are blamed on human errors of the fisher and skipper, but safety accidents occur due to a mixture of mechanical and equipment factors, work and environmental factors, and management factors in addition to human errors. Therefore, the 4E were presented as countermeasures against the 4M, which are causes of safety accidents, and the proposed measures were used to identify risk factors for operation process, comply with work safety rules, and ensure the wearing of personal protective equipments. We need to reduce safety accidents during work by making it part of our daily routine. These research results can be used in the future for optimal placement of fishing gear and fishing nets in other coastal industries where safety accidents occur frequently.

In this study, we estimated the distribution density of giant jellyfish in coastal waters of Korea in 2023 and compared the occurrence of giant jellyfish over four years. In May, the giant jellyfish were mainly distributed in the waters of the Yangtze River outflow, and in July, they were highly distributed in the west of Jeju Island and near the south coast of Korea. In addition, when comparing the distribution densities of giant jellyfish in Korea over four years, both acoustic and sighting surveys showed that the highest density of jellyfish occurred in 2021.

This study examined the power consumption of angling boats during entry, departure, and fishing operations using a black box-type storage device. Through this analysis, it determined the energy consumption and carbon emissions of small fishing boats used for catching the largehead hairtail. The energy consumption and carbon emissions were calculated using formulas provided by the Korea Energy Agency, which incorporated updated emission coefficients from 2022. The findings revealed that the average power consumption of small fishing boats for the largehead hairtail was 546.3 kWh, with a total energy consumption of 0.1164 TOE and carbon emissions of 24.057 CO2. The average energy consumption was calculated at 0.0006 TOE per kilogram, and the carbon emissions were determined to be 0.135 CO2/kg.

As discarded fishing gear settles or floats on the seabed, it destroys the spawning and habitat of fisheries resources that causes various safety accidents and adverse effects on the environment, such as generating microplastics and causing ship accidents. In order to solve this problem, this study is intended to present an implementation plan for establishing a fishing gear deposit system in order to use it as basic data for establishing policies for fishing gear management in Korea. In order to successfully implement the fishing gear deposit system, the deposit system must be established in the form of fishing gear completed at the production stage. It was found that the marking of the object should be easy, and that determining an appropriate deposit amount to motivate the return of waste fishing gear and establishing a convenient return procedure for returned waste fishing gear were important factors. In addition, transparent management of unreturned deposits and mandatory use of fishing gear subject to the deposit system for fishermen will be necessary. The role of a specialized organization to manage and operate all of these procedures is also very important. It is necessary to establish a new mandatory provision in the Fisheries Act to require fishermen who directly use fishing gear to use fishing gear with a deposit refund mark, and to ensure the implementation of the deposit system by linking it with the evaluation items of government policy projects. Since the main purpose of the deposit system is to collect discarded fishing gear, a support plan will be necessary in accordance with the purchase project for fishing waste salvaged by local governments in 2020.

In this study, we aimed to determine the seasonal distribution and biomass of fish in Samcheok marine ranching area (MRA) of Republic of Korea using the scientific echosounder. Fish trap and gillnets were used to identify fish species in the survey area, and dB-difference method was used to estimation the spatio-temporal distribution and density of fish. The results showed that the dominant species in Samcheok marine ranching area were Chelidonichthys spinosus, Sebastes inermis, Hexagrammos otakii and Tribolodon hakonensis. The spatio-temporal distribution of fish showed that fish had a relatively higher distribution at night than during the day. In addition, the density of fish by season was highest at night in July at 34.22 g/m 2 and lowest in April at 0.42 g/m 2 .

This study was investigated in order to find composition and density of fisheries resource using bottom trawl in April, July, August, and November 2022 in the East China Sea. The average density of fisheries resource was estimated using the swept area method. As a result, 35 species were collected from the East China Sea. These included 21 fishes, six crustaceans, six cephalopods and two echinoderms. Seasonally, the average density of crustacean individuals per unit area were highest in November (692.1 inds./km 2 ), while cephalopod individuals per unit area were highest in August (39.4 inds./km 2 ). The average density of fish individuals per unit area were highest in August at 355.0 (inds./km 2 ).