PURPOSES : The objective of this study is to develop an optimal placement of the overturning prevention device based on a 3D object model during the development of the girder-type overturning prevention device for the remote control construction of bridges METHODS : Based on existing construction methods and literature research, a detailed design model of a phase-optimized conduction prevention device is presented. The 3D-object model data, optimal placement, and an operating range of the equipment developed for the remote control construction of bridge girders were considered. RESULTS : The shape of the overturning prevention device was selected taking into account the dimensions and operating range of numerous devices developed for the remote control construction of the bridge. In particular, the detachable device was chosen to allow a trouble-free construction considering the spacing between the pier cap of the bridge and the girders. The overturning prevention device presented based on this 3D object model will be manufactured as a mock-up and used for a demonstration project on remote control bridge construction. CONCLUSIONS : This will enable easy and economical construction as this development will support remote control construction of bridge girders to avoid accidents such as workers falling from high places like piers.

PURPOSES : Preventive pavement maintenance is an economical and efficient method of infrastructure management. This study aims to improve the performance of cold thin-layer asphalt pavement, which is mainly used in earthwork pavement, and for bridge overlays and structures. METHODS : A cold asphalt mixture of modified emulsified asphalt and RAP was prepared for cold recycled thin-layer asphalt pavement. The performance of the mixture as a function of fiber reinforcement to improve flexural strength and crack resistance was evaluated. RESULTS : The use of RAP aggregate in cold asphalt mixture was found to increase the cohesive strength of the mixture and improve the wet abrasion resistance due to the effect of the residual binder. As a result of the loaded wheel test and flexural tension test with the addition of fiber reinforcement, it was found that the crack resistance of 0.4 % glass fiber was the best, and especially, the flexibility at low temperature was excellent. CONCLUSIONS : The cold recycled thin-layer asphalt pavement mixture has improved cohesive strength, flexural strength, and crack resistance compared to existing cold asphalt pavement materials, so it will contribute to economical and effective maintenance in preventive maintenance of bridge overlays and structural pavements.

PURPOSES : This study evaluates the long-term performance of the asphalt overlay designed by the Seoul pavement design method which determines overlay thickness by considering existing pavement conditions, traffic volume, and bearing capacity of the pavement. METHODS : A total of 76 sections including 17 control sections and 59 design sections were constructed under various traffic conditions, overlay thicknesses and asphalt mixtures. The performance of the pavements has been monitored up to 60 months in terms of surface distresses, rutting, and longitudinal roughness. The service life of the pavements was estimated to be the period when the Seoul pavement condition index (SPI) becomes 6.0, i.e., a rehabilitation level. RESULTS : Overall, the service life of the pavements was 72 months in the control and 120 months for the design sections. For relatively thinner overlay sections than designed, the service life reduced significantly; 36 months for 15cm thick overlay and 120 months for 25cm thick overlay. The service life of the pavement in the bus-only lane was 78 months, which is 30 months shorter than that in mixed-traffic lanes. Out of the bus-only lanes, 56% of the pavement along bus stop was deteriorated early to be a poor condition while only 2% of the pavement in a driving lane was degraded to be poor. The overlay with Stone Mastic Asphalt (SMA) in the wearing surface had 38% longer life than that with conventional dense graded mixtures. CONCLUSIONS : Most of the overlays sections designed by the Seoul pavement design method were expected to survive 10 years, except for bus-only lanes. The control sections having 5 to 10 cm thick overlays showed significant lower performance than the design sections. Thus proper thickness and materials considering the characteristics of existing pavement and traffic volumes should be applied to secure the service life of overlays.

중국 동북부지역 랴오닝성의 단둥(40°07'N 124°23'E)과 지린성의 궁주링(43°30'N 124°49') 및 룽징(42°46'N 129°26'E)에서 2020년과 2021년 벼 재배기간 중에 성페로몬트랩으로 이화명나방(Chilo suppressalis)(나비목: 포충나방과)의 성충 발생 시기를 조사하였다. 1화기 성충은 5월 중순부터 7월 하순 사이, 2화기 성충은 7월 중순부터 9월 중순 사이에 발생하여 세 지역 모두 연중 2회 성충 발생양상이 뚜렷하게 확인되었 다. 위도가 높은 지역에서 발생시기가 더 늦었다. 각 지역에서 관찰된 1화기 발생 시기를 기준으로 발생 시기 모델링을 통해 2화기 발생 시기를 추 정하고 관찰된 시기와 비교하였다. 네 개의 선행연구 자료로부터 성충, 알, 유충, 용 발육단계의 온도의존 생명현상(발육속도, 발육완성분포, 생존 율, 성충 노화율, 총산란수, 산란완성분포, 성충 생존완성분포) 모델들을 수집하거나 작성하였고, 이들을 선행 연구에 따라 단독으로 사용하거나 혼합하여 곤충 발생 시기 추정 소프트웨어인 PopModel에서 결합하였다. 모델링 결과에서 유충 발육기간이 짧게 관찰된 선행연구 자료를 기반으 로 하여 구성된 모형들이 2화기 성충 발생 시기를 더 근접하게 추정하였다. 2021년에는 단둥과 룽징에서 성충 조사 시기에 맞추어 이화명나방에 의 한 벼 피해주율의 변화를 조사하였다. 피해주율은 벼 재배기간 중 누적되어 2번의 증가시기가 뚜렷하게 나타났고, 이화명나방의 각 세대 유충에 의 해 발생한 것으로 추정되었다.

Fisheries is known as a high-risk industry in Korea, and various efforts have been made to reduce occupational accidents. Trap fisheries represent crustacean production, accounting for 4.7% of total fisheries production and 10.7% of its production value, which is classified as a relatively high-risk industry. With the disaster insurance payment data of the National Federation of Fisheries Cooperatives (NFFC) from 2016 to 2020, the accident rate of the entire fishery, the accident rate of trap fisheries, and the type of disasters in the past five years were analyzed. As a result, the average fishery accident rate for the past five years was 5.31%, but it was high at 6.15% for coastal trap fisheries and 5.59% for offshore trap fisheries. Slips and trips, struck by objects and contact with machinery were the most common types of the accident according to the characteristics of the work, and hand injuries were analyzed the most. Additional efforts, including education for accident prevention, development of personal protective equipment and improvement of the working environment, are needed to prevent accidents caused by repeated types of disasters.

As a series of basic research to draw the pilot design measures for developing the habitat apparatus of Sulculus diversicolor supertexta inhabiting the coastal area of Jeju island, this study conducted a water tank experiment to understand the habitat marine environment of Sulculus diversicolor supertexta and the preference of habitat space focusing on the research fisheries performing the discharge of marine products. In the composition degree of marine algae in both fisheries, Donggwi-ri showed the highest gulfweed (79.3%) as brown algae and there were some coralline algae (17.2%) as red algae. Hansu-ri yielded the highest gulfweed (48.1%) as brown algae, which was followed by sea lettuce (10.4%) as green algae. In the preference of habitat space, the shelter angles 40° showed the highest adhesion as number of 82.9, which was followed by 60° and 70° as 69.2 and 68.2 respectively (P<0.05) by reviewing the environmental characteristics of habit of Salculus diversicolor supertexta in the coastal fishery of Jeju Island, when considering the adhesion rate in each of five shelters with different angles. In the future, there should be continuous research and monitoring for designing the fish shelters suitable for the coastal fisheries of Jeju island, and it would be also necessary to add the field-centered sustainable concrete research.