PURPOSES : In general, a high-performance concrete construction method is a method of loading mixed cement and other materials on a mobile mixer equipped with a concrete plant. However, the construction cost is high because the unit cost of the mixed cement is very high and the equipment usage fee of the mobile mixer is also high. To compensate for these drawbacks, a cellular spray concrete method was developed. This is a highly functional customized concrete construction method in which admixtures are added to high-flow concrete with cellular (air bubbles) added at the site and constructed through spraying. METHODS : Field workability evaluation using cellular concrete was carried out using a spray method in 2017 and an anti-foaming agent in 2018. The test construction section was set as a new road-pavement construction site. After construction, strength, durability characteristics, and void analysis were performed to compare the construction methods. The results of laboratory tests under optimal conditions were also compared to the on-field results. By comparing the indoor mixing and the on-field results, we analyzed whether there were any problems concerning the performance expression. The economic feasibility at the initial construction stage was analyzed by comparing the existing and the cellular concrete construction methods in terms of material cost and equipment usage fee. RESULTS : In the case of cellular spray concrete, construction through spraying is cumbersome, and the need to additionally use large equipment such as a pump car and compressor constitutes a disadvantage. However, the most relevant feature is that it can be constructed not only on the floor, but also on a slope. In the case of cellular concrete with an antifoaming agent, it was possible to quickly produce high-performance concrete using on-site remixing equipment. By supplying materials to the pouring surface using a conveyor, smooth construction and construction in narrow spaces were also possible. CONCLUSIONS : The cellular concrete method allows the immediate on-site production of high-performance concrete, and it is possible to selectively apply spray construction, antifoaming agent construction, etc.

기존 포장에서 고내구성과 조기강도 발현을 위하여 쓰이고 있는 바인더의 경우, 고가의 폴리머를 다량 으로 사용하고 속경성 시멘트를 적용한다. 또한 단위시멘트 360 kg/㎥이상의 부배합 시멘트를 적용하고, 양질의 골재를 사용하고 있다. 이로 인하여 재료비가 증가하게 되고 시공을 위한 고가의 특수 장비를 운 영해야 하기 때문에 공사비가 증가된다. 이러한 문제점을 해결하기 위하여 콘크리트의 내구성을 증진시켜 주는 산업폐기물로 시멘트를 치환하고, 현장 레미콘을 사용하여 재료 단가를 낮춰 줌으로써 경제성을 확 보 할 수 있다. 레미콘에 현장에서 직접 혼화재료를 투입하기 때문에, 혼화재료 투입의 효율을 증대시키 기 위한 장비개발을 위한 연구가 필요시 된다. 따라서 기존에 인력으로 투입되던 혼화재료를 현장생산 system(기포발생장치)를 이용하여 레미콘에 투입하고, 인력투입대비 공정효율을 증가시키는 것이 본 연 구의 목적이다. 현장생산system(기포발생장치)를 이용하여 개선된 방안을 토대로 공정 효율을 비교한 결과 인력투입대 비 약 140% 이상 효율이 증대되는 것을 확인하였다.

온라인 게임에 대한 수요가 증가하면서 많은 사용자들은 다양한 무선 접속 기술들을 이용하여 장소에 구애받지 않고 게임 컨텐츠를 이용할 수 있게 되었다. 모바일 기반에서 온라인 게임 컨텐츠 및 시나리오를 신속하게 내려받기 위해서는 무선링크를 통한 전송속도가 충분히 확보되어야 한다. 본 논문에서는 이동/무선 환경에서 고속의 데이터 전송을 지원하는 대표적인 3세대 이동통신 표준인 WCDMA/HSDPA 시스템의 기본적인 개념과 핵심 요소들을 소개하고 온라인 게임의 향후 발전 방향을 전망한다.

In designing and operating cellular networks, it is assumed that the area of coverage is geographically divided into hexagonal cells. Among these cells, a certain number of cells are chosen to install switches that serve as relays for communications between any pair of cells. Then, each cell is assigned to a switch to complete the cellular network. This decision regarding assignment of cells to switches is known as a CSA (Cell-to-Switch Assignment) problem. Since this problem is so-called NP hard problem, many researches have proposed heuristic-based algorithms to provide near-optimal solutions with a reasonable computation time. Considering these characteristics of the CSA problem, this work develops a genetic algorithm and a local search algorithm. Throu호out a number of experiments, the performance of the proposed algorithms are evaluated, and compared with existing heuristic method