Complaints about foul odors are emerging as an issue, and the number of complaints is steadily increasing every year. Biofiltration is known to remove harmful or odorous substances from the atmosphere by using microorganisms, and full-scale biofilters are being installed and operated in various environmental and industrial facilities. In this study, the current status and actual odor removal efficiency of full-scale biofilters installed in publicly owned treatment facilities such as sewage, manure, and livestock manure treatment plants were investigated. In addition, the effects of design and operating factors on their efficiency were also examined. As a result, it was found that odor prevention facilities with less than 30% odor removal efficiency based on complex odors accounted for 40%-50% of the biofilters investigated. In investigating the appropriate level of operating factors on odor removal efficiency, it was found that compliance with the recommended values p lays a significant role in improving odor removal efficiency. In the canonical correlation analysis for the on-site biofilter operation and design data, residence time and humidity were found to be the most critical factors. The on-site biofilter operation and design data were analyzed through canonical correlation analysis, and the residence time and humidity maintenance were found to be the most important factors in the design and operations of the biofilter. Based on these results, it is necessary to improve the odor removal efficiency of on-site biofilters by reviewing the effectiveness of the operation factors, improving devices, and adjusting operating methods.

Eutrophication and algal blooms can lead to increase of taste and odor compounds and health problems by cyanobacterial toxins. To cope with these eco-social issues, Ministry of Environment in Korea has been reinforcing the effluent standards of wastewater treatment facilities. As a result, various advanced phosphorus removal processes have been adopted in each wastewater treatment plant nation-widely. However, a lot of existing advanced wastewater treatment processes have been facing the problems of expensive cost in operation and excessive sludge production caused by high dosage of coagulant. In this study, the sedimentation and dissolved air flotation (SeDAF) process integrated with sedimentation and flotation has been developed for enhanced phosphorus removal in wastewater treatment facilities. Design and operating parameters of the SeDAF process with the capacity of 100 m3/d were determined, and a demonstration plant has been installed and operated at I wastewater treatment facility (located in Gyeonggi-do) for the verification of field applicability. Several empirical evaluations for the SeDAF process were performed at demonstration-plant scale, and the results showed clearly that T-P and turbidity values of treated water were to satisfy the highest effluent standards below 0.2 mg/L and 2.0 NTU stably for all of operation cases.

This study is carried out to analyze the velocity distribution for each location and the uniformity index according to straight distance on exit side by changing the design factors of branch pipe connected to 180° circular mixing-tee using RSM(Reynolds Stress Model) turbulence model. As the results of the flow characteristics according to hydraulic diameter, the velocity profiles in the 90° sectional area are generally similar. In the 180° section, the maximum velocity point shows Y/D=0.7~0.8 after rapid increase of the flow velocity. In the result according to the distance away from inlet, the maximum velocity point in the 90° sectional area is located in outer side of the curved pipe as the distance away from inlet increases. In the 180° sectional area, the maximum velocity point is showed in Y/D=0.7~0.8 after the rapid increase of the flow velocity regardless of the variation of branched distance. In case of inclined angle, the maximum velocity point in the 90° sectional area is located in outer side of the curved pipe as the inclined angle increases. In the 180° sectional area, the maximum velocity point is observed in Y/D=0.8 regardless of the inclined angle. In addition, the uniformity index of flow velocity shows that it is stabilizing after approximately L/D=40 away from the end of the curved pipe regardless of the flow factors in the branch pipe.

The algal blooms in stagnant streams and lakes have caused many problems. Excessive algae leads to disturbance of ecosystem and overload of water treatment processes. Therefore, phosphorus(P), source of algal blooms, should be controlled. In this study, a filtration trench has been developed to convert dissolved phosphorus into hydroxyapatite(HAP) so that it could be crystallized on the surface of ‘phosphorus removal granular material’; and residual particulate phosphorus could be removed by additional precipitation and filtration. The front and rear parts of filtration trench consisted of ‘phosphorus removal granular material contact bed’ and ‘limestone filtration bed’, respectively. As a result of the column test using phosphorus removal granular material and limestone serially, PO4-P was removed more than 90% when EBCT(empty bed contact time) of the contact bed was over 20 minutes; and T-P represented 60% of removal efficiency when total EBCT was over 1.5 hours. The results of column tests to figure out the sedimentation characteristics showed that more than 90% of particulate phosphorus could be removed within 24 hours. It was necessary to optimize the filtration part in order to increase removal efficiency of T-P additionally. Also, it was confirmed through the simulation of Visual MINTEQ that most of particulate phosphorus in the column tests is the form of HAP. Based on the results of the study, it could be suggested that the design parameters are over 0.5 hour of EBCT for phosphorus removal granular material contact bed and over 1.5 hours of EBCT for limestone filtration bed.

Water quality improvement processes for stagnant area consist mainly of technologies applying vegetation and artificial water circulation, and these existing technologies have some limits to handle pollution loads effectively. To improve the purification efficiency, eco-friendly technologies should be developed that can reinforce self-purification functions. In this study, a multi-functional floating island combined with physical · chemical · biological functions (① flotation and oxidization using microbubbles, ② vegetation purification and ③ bio-filtration with improved adsorption capacity) has been developed and basic experiments were performed to determine the optimal combination conditions for each unit process. It has been shown that it is desirable to operate the microbubble unit process under conditions greater than 3.5 kgf/cm2. In vegetation purification unit process, Yellow Iris (Iris pseudacorus) was suggested to be suitable considering water quality, landscape improvement and maintenance. When granular red-mud was applied to the bio-filtration unit process, it was found that T-P removal efficiency was good and its value was also stable for various linear velocity conditions. The appropriate thickness of filter media was suggested between 30 and 45 cm. In this study, the optimal design and operating parameters of the multi-functional floating island have been presented based on the results of the basic experiments of each unit process.

Construction techniques and materials are developing and structures are designed to be irregular shaped, and therefore more detailed structural analysis is required. The purpose of this study is to analyze the cause of accidents related to falsework systems during construction and discuss prevention methods in order to prevent accidents relate to prefabricated shoring system during construction. In this paper structural analysis was conducted to study the influence of slab irregularity on system supports and analysis to investigate the participation of the bracing in the system support.

최근에는 도심지 개발에 따른 지표면 포장률 증가로 인해 불투수면적의 증가하여 지하수의 고갈, 도시형 수해 증가 등의 문제가 발생하고 있다. 투수성 포장기법은 대표적인 저영향개발적용 기술 중 하나인 친환경 포장 공법으로 물순환 체계의 개선을 통한 환경 개선 효과와 더불어 차량 주행소음의 감소, 열섬 현상 완화, 미끄럼 저항의 향상 등 다양한 기능을 얻을 수 있으며 국내외 관련 연구가 활발히 진행되고 있다. 현재 일반도로는 한국형 포장설계법을 적용하여 설계를 하게 되어 있으나, 현재 투수성 아스팔트 도로를 설계를 위한 지침은 제시되어 있지 않다. 이에 본 연구에서는 국내외 선행 연구 조사 및 검토를 통해 투수성 아스팔트 포장 설계인자 및 구조 설계방법을 제안하고자 한다. 선행 연구 조사 결과, 투수성 포장 구조설계는 AASHTO 1993 설계법을 적용하여 수행하고 있는 것으로 확인되었다. 투수성 포장 설계인자 중 투수성 아스팔트 포장재료의 상대강도계수를 제안하였고, 한국형 설계법에서 고려하고 있는 도로설계등급을 고려하여 교통량 산정하는데 적용하였다. 또한, 투수성 콘크리트 포장설계를 위한 지지력 복합계수를 한국형 설계법에서 적용한 방법을 활용하여 구조 설계에 고려하였다. 이러한 설계인자를 고려하고 경제성을 고려한 최적 포장 두께를 산정하기 위한 최적화 알고리즘을 적용설계를 할 수 있는 PerPaveDesign 프로그램을 그림 1과 같이 개발하였다.

RTG (Radioisotope Thermoelectric Generator) is a power generation system producing electricity by converting the thermal energy gained from shielding radioisotope. RTG generates power without being charged from outside and as it utilizes radioisotope, RTG mainly serves as an energy source operated for a specific purpose in environment hardly accessible by human. Its design structures vary according to its purpose of operation, thermal source of operation and environment of operation. Since RTG is a power generation system, it should have the highest power efficiency with limited heat source. In this study, heat transfer analysis was implemented to investigate diverse design factors influencing the insulation system of RTG for aerospace use. Design factors considered in this study were silver coating, number of radiation shields inside vacuum insulation and supporter material. As a result, it was found that, depending upon design factors, insulation efficiency increased by 9.3% and finally insulation efficiency of RTG v2.0 was estimated at 84.3%.

재래식 해수담수화 수평적 압력용기 설계는 후단에 있는 역삼투막에는 농축수에 의해 수질악화 및 생산수저감 등이 동반된다. 이를 해결하기 위해 본 연구에서는 개념적인 중앙 주입식 압력용기가 생산수 단가에 미치는 영향과 역삼투 공정 설계 시 주요 인자들이 성능에 미치는 영향을 조사를 위해 상업화된 역삼 투 프로그램인 ROSA를 이용하여 분석하였다. 그 결과 중앙 주입식 압력용기를 이용할 경우 총괄적인 회수율과 SEC 측면에서 성능이 저하하지만, 막 모듈 당 생산되는 생산수량이 증가하는 것으로 나타났다. 또한 생산수의 수질개선은 2단 설계의 용량 감소로 인하여 건설비 저감으로 연계되는 것으로 조사되었다. 본 연구는 국토교통부 플랜트연구사업의 연구비지원(과제번호 16IFIP-B089908-03)에 의해 수행되었습니다.

An eductor is an fluid transportation simplified device that generate relatively low pressure utilizing the kinetic energy of pressured fluid to provoke suction of another fluid, mix the two and discharge the mixture against a counter pressure. In this study, a parameter analysis was conducted to predict the eductor performance against various operating conditions.

국내의 방음시설은 비교적 저렴하고, 설치 및 시공이 간단한 방음벽에 초점이 맞춰져 왔다. 특히, 반사형 방음패널의 경우 흡음형 방음패널과 같은 불투명형 방음벽과는 달리 시야를 가리지 않으므로 방음시설을 요구하는 거주자들에게 인기를 얻고 있다. 그러나 흡음의 효과가 거의 없어 방음벽을 설치한 반대측의 거주자에게 2차 피해를 야기할 수 있다. 따라서 반사형 방음패널의 형태를 개량하여 시야를 가리지 않는 범위에서 피해를 줄일 수 있는 방안마련의 필요성이 제기되고 있다. 이에 반사형 방음 패널의 전면 형상 및 기하학적 형태를 변화시켜 반사음의 전달이 방음벽 설치 반대방향으로 나아가는 것을 최소화 시킬 수 있는 형상을 도출하고자 하였다. 설계형상 및 설계인자는 그림 1과 같으며, 반사소음 평가는 방음벽이 설치되지 않은 맞은편 도로의 15m(R1), 30m(R2)높이를 목표지점으로 설정하였다. 추가로 도로내측(R3)의 경우 평판형 대비 소음이 증가여부를 확인하기 위하여 선정하였다. 방음벽 설계인자는 표 1에 제시하였으며 위 경우의 소음도를 예측하였다. 그 결과 방음벽 A와 B의 경우 평판 형에 비해 R1지점에서 반사소음을 저감하는 것이 확인되었으며, 특히 A의 경우 2.2 dB(A)의 소음이 감소되어 가장 좋은 결과를 나타내었다. R2지점은 0.2~0.7dB(A)의 소음이 증가하였고, B와 C방음벽은 모든 지점에서 0.1~0.2 dB(A)의 소음이 증가하였다. 결론적으로, 방음벽의 설계인자에 따라 반사소음 증감이 나타났고 방음벽 설계인자중 θ값이 작을수록 저감효과가 좋은 것을 확인하였다. 따라서 방음벽 형상에 따른 반사소음저감 기술개발의 가능성을 확인하였다.

In the car speaker, because the sound characteristics is changed by the space of car which mount the speaker, the speaker elements must be decide according to sound field. In this study, the mass of cone paper and damper is changed and the characteristics of the sound pressure and loudness are investigated by the experimental approach. According to the change of the speaker characteristics, the sound pressure and loudness level are changed. The effect of the con paper is larger than that of the damper in the aspect of the loudness. In the future, these data will be used to investigate the correlation between the sound quality and measurement data.

This study is concerned about the optimal design of the main frame in a moper. Mopper is widely used for cleaning in the fields such as airport, subway, train station, large shopping mall, department store, hospital, government buildings, school, industrial building floor, etc. Especially, main frame in mopper are stressed by high, mostly loads. Nevertheless, design of main frame is dependent on experience, and it will cause reliability reduction and cost increase. This research purpose is to propose and verify a method to achieve higher product quality, lower costs, and far less physical testing. In this study, design parameters used for optimization are each thickness of 4 square pipes and 1 plate in the main frame. The result after optimization showed that the weight of main frame reduced to maximum 6.5% when compared with the initial design in main frame.

원자력발전소에서 나온 사용후핵연료 건식저장시스템의 안전한 운영과 유지는 기본적으로 적절하게 선택 된 설계기준에 좌우된다. 저장시스템의 가장 중요한 설계목표는 저장된 사용후핵연료로부터 작업자의 안전과 대중에게 과도한 위험이 없이 보관, 취급, 수납 및 감시할 수 있는 신뢰를 제공하는 것이다. 이러한 목표를 달성하려면, 시스템의 설계, 사용후핵연료로부터의 잔류 열을 제거하고 방사선 차폐를 제공함과 동시에 설계 기 준에 지정된 시스템의 수명동안 격납을 유지하기 위한 기능을 포함한다. 운영 중 발생가능한 설계사항은 설 계 기준에 반영되어야 한다. 본 논문에서는 건식저장시스템의 일반적인 성능 요구 사항을 소개하였다. 저장시 스템은 인허가를 위한 규제 요구 사항과 연관하여 사용후핵연료를 저장할 수 있도록 설계된다. 여기서 최대연 소도의 증가는 냉각기간과 맞물려 가감할 수 있다. 이때 열부하와 방사능의 크기가 최대 설계기준 연소도의 기준을 설정하는 주요한 인자가 된다. 이외에 건식저장시스템의 설계기준사고와 다른 분야 즉 기계 및 구조 그리고 차폐 및 방사선적인 요구사항들의 종류가 기술되었다.

The paper reviews gauge R&R studies by two-factor mixed models including random and fixed factors. The two-factor mixed models include restricted models and unrestricted models considering the interaction of two factors. This study also classifies the models according to the number of factors, and the combination of various factors such as random factor, fixed factor, block factor and repetition type.