This paper aims to quantify the retrofit effect of the Bolt Prefabricated Concrete-Filled Tube reinforcement method on non-seismic school reinforced concrete building through static cyclic loading experiments. To achieve the objective, two-story specimens including a non-retrofitted frame(NRF) and a Bolt Prefabricated Concrete-Filled Tube Reinforcement Frame(BCRF) were tested under static cyclic loading, and the lateral resistant capacities were compared in terms of maximum strength, initial stiffness, effective stiffness, and total energy dissipation. In addition, the load-displacement curves were compared to the story drift limit specified in Seismic Performance Evaluation and Retrofit Manual for School Facilities to investigate if the retrofitted frame was satisfied in target performance(life safety). Experimental results showed that BCRF successfully met the target performance, with a 200% increase in maximum strength and a 300% increase in energy dissipation capacity. Additionally, both initial stiffness and effective stiffness improved by more than 30% compared to NRF. Furthermore, BCRF exhibited an effect that delayed the occurrence of bond failure.

Wastewater management is increasingly emphasizing economic and environmental sustainability. Traditional methods in sewage treatment plants have significant implications for the environment and the economy due to power and chemical consumption, and sludge generation. To address these challenges, a study was conducted to develop the Intermittent Cycle Extended Aeration System (ICEAS). This approach was implemented as the primary technique in a full-scale wastewater treatment facility, utilizing key operational factors within the standard Sequencing Batch Reactor (SBR) process. The optimal operational approach, identified in this study, was put into practice at the research facility from January 2020 to December 2022. By implementing management strategies within the biological reactor, it was shown that maintaining and reducing chemical quantities, sludge generation, power consumption, and related costs could yield economic benefits. Moreover, adapting operations to influent characteristics and seasonal conditions allowed for efficient blower operation, reducing unnecessary electricity consumption and ensuring proper dissolved oxygen levels. Despite annual increases in influent flow rate and concentration, this study demonstrated the ability to maintain and reduce sludge production, electricity consumption, and chemical usage. Additionally, systematic responses to emergencies and abnormal situations significantly contributed to economic, technical, and environmental benefits.

In this paper, a tidal power conversion system (PCS) using seawater level differences was presented.. To verify the presented PCS, an actual lab-scale tidal power generation system was constructed. The operation of the lab-scale PCS was first modeled mathematically and was analyzed through dynamic simulation and experimental tests.

In this paper, the CFRP(Carbon Fiber Reinforced Plastic) parts were printed and cut in a large-scale additive and subtractive hybrid manufacturing system. A method to increase the strength and durability of a product by identifying the interlayer adhesion during the printing process of a large-scale additive manufacturing hybrid system was investigated. According to the printing conditions(CF content, deposition temperature, compaction process), the specimen was printed and cut to determine the tensile strength in the printing direction. As a result of the experiment, the highest tensile strength was shown when ABS-CF 20wt.% Compound was printed at 230℃ extrusion temperature, and the higher the CF content of the material, the lower the tensile strength. As a result of observing the inside of the test piece through an optical microscope, a large number of voids were kept inside the test piece. To remove voids generated inside the test piece, a compaction process was applied to the additive manufacturing hybrid system to prepare a test piece. As a result, void size decreased, and the strength of the part showed a tendency to increase. It is thought that additive manufacturing with high tensile strength can be obtained through studies on the optimization of deposition conditions in additive manufacturing hybrid systems.

In this study, the following results were obtained by designing a high-efficiency hydrogel and colloid fusion applicator and checking production speed(hydrogel) and working setting time(coating time) by promoting the starting product. As a result of performing a product production test by manufacturing a starting product based on the process automation design, the production volume increased by about three times from 4m per minute to an average of 11m per minute. The working setting time(coating time) of the fusion applicator was shortened from the target of 10minutes to 1.69minutes, which had the effect of reducing the loss of work time.

In this study, we learned about the effects of indoor radon concentration reduction associated with the operation of a mechanical ventilation system at an apartment house. The experimental parameters were mainly the indoor radon level and air change rate, which were controlled by the amount of emissions released and fan motor speed. Even at the high level of radon diffused in an apartment house, indoor radon concentrations converged to the Korean national guideline level within 3 to 4 hours when the air was ventilated at 0.5 ACH and 0.7 ACH. In the case of 0.3 ACH, however, where the degree of ventilation was insufficient compared to the legal air change rate, the high concentration indoor radon could not be sufficiently removed even if the mechanical ventilation system was operated for more than 14 hours continuously. When the indoor radon level was high, the reduction rate was 34.3% for 0.3 ACH, 70.4% for 0.5 ACH, and 69.7% for 0.7 ACH at 6 hours-operation, while at the medium-level, indoor radon can be reduced by 46.2% (0.3 ACH) to 73.2% (0.7 ACH). Depending on the indoor concentration range, it may be required to secure a ventilation rate of 0.5 ACH or more at all times. In addition, in apartment houses with excellent airtight performance, even if indoor radon is at a level similar to the national guideline, it is difficult to expect a reduction in the concentration due to natural decay. Therefore, it is desirable to lower the indoor concentrations as much as possible.

Numerical analysis has been carried out to investigate the characteristics of seawater flow fields and turbine output in a compact double current tidal power generation system for various level differences. There are growing concerns for the development of efficient tidal power generation which is stable and less affected by environmental circumstances as ocean energy. Especially the flow field characteristics in the compact tidal power generation system have a large influence on the system power generation performance. Flow velocity, pressure, and streamline distributions are compared including vertical type turbine out, and it can be predicted that seawater is accelerated by vortex flow in front of the turbine and there is severe turbine output variation due to the water level difference with pressure difference. These results can be applied as basic data for the effective development of compact tidal power generation system.

본 논문은 대형 시설물의 점검 및 진단을 위한 외관조사시 영상기반 스캐닝 시스템의 성능 및 정확도를 정량적으로 평가하기 위한 것으로, 도로터널, 철도터널, 지하철과 같은 대형 터널 시설물의 복공 라이닝을 대상으로 영상기반 스캐닝 분석 결과, 균열, 박리, 박락, 철근노출 등 각종 손상의 검출 성능과 정확도를 육안조사, 터널 스캐닝 분석 후 확인조사 데이터를 이용하여 비교 분석하였다. 제안된 터널 스캐닝 시스템의 균열손상 검출성능은 육안조사 분석결과 대비 개소 수 및 면적물량에 있어 월등히 우수함을 확인하였으며, 균열손상 증감을 고려한 균열손상은 현장 확인조사 결과 95%이상의 검출 정확도를 확보하고 있는 것으로 평가되었다.

Large-scale cultivation of Microcystis aeruginosa in different light conditions was conducted for verifying the cell growth in a greenhouse system. Environmental and chemical parameters of the large-scale culture medium were measured for analyzing the interaction between M. aeruginosa and its symbiotic bacteria. During cultivation, a difference in cell growth pattern was observed between control (natural light) and lightlimited groups (reduction of blue, green, and blue/green light, respectively). Comparing the control group, the light reduced groups showed slow and delayed cell growth through the cultivation period. Also, there is differences in the consuming pattern of total nitrogen and total phosphorus which indicated that the possibility of interaction between M. aeruginosa and symbiotic bacteria.

본 연구에서는 합성가스의 에너지화를 위한 가스엔진 성능 평가를 수행하였다. 회전수 1800 rpm 조건에서 공기과잉률이 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6 증가에 따른 엔진출력(kWm)과 열효율(%)을 평가한 결과, 공기과잉률 λ 1.4에서 엔진출력 34 kWm를 나타냈으며, 공기과잉률이 증가할수록 엔진 열효율은 전반적으로 감소하는 경향을 보였다. 엔진출력 34 kWm 조건에서 공기과잉률이 1, 1.1, 1.2, 1.3, 1.4 증가시 열효율이 34.2%, 36.9%, 37.2%, 37.4%, 38.1%로 증가하였고, 발전출력을 통한 종합효율은 발전출 력 30 kWe 부하조건에서 38.7 kg/h의 연료를 소모하여 32.1%의 발전효율과 냉각수와 배기가스에서의 열 회수를 통해 57.3 kW의 폐열을 회수하여 53.8%의 열을 회수하여 총 85.8%의 종합효율을 보이는 것으로 나타났다.

Effects of a commercial scale intervention system combining ultraviolet (UV)-C and plasma treatments on the microbial decontamination of black pepper powder were investigated. The process parameters include treatment time, time for plasma accumulation before treatment, and water activity of black pepper powder. A significant reduction in the number of indigenous aerobic mesophilic bacteria in black pepper powder was observed after treatments lasted for ≥ 20 min (p<0.05) and the reduction was differed by powder manufacturer. The microbial reduction rates obtained by individual UV-C treatment, individual plasma treatment, and UV-C/plasma-combined treatment were 0.2, 0.5, and 1.0 log CFU/g, respectively, suggesting that the efficacy of the microbial inactivation was enhanced by treatment combination. Nonetheless, neither plasma accumulation time nor powder water activity affected the microbial inactivation efficacy of the combined treatment. The UV-C/plasma-combined treatment, however, decreased lightness of black pepper powder, and the decrease generally increased as operation time increased. The plasma accumulation time of 20 min resulted in significant reduction in both lightness and brown color. The results indicate that the commercial-scale intervention system combining treatments of UV-C and plasma has the potential to be applied in the food industry for decontaminating black pepper powder.

Existing reinforced concrete building structures have seismic vulnerabilities due to their seismically-deficient details resulting in non-ductile behavior. The seismic vulnerabilities can be mitigated by retrofitting the buildings using a fiber-reinforced polymer column jacketing system, which can provide additional confining pressures to existing columns to improve their lateral resisting capacities. This study presents dynamic responses of a full-scale non-ductile reinforced concrete frame retrofitted using a fiber-reinforced polymer column jacketing system. A series of forced-vibration testing was performed to measure the dynamic responses (e.g. natural frequencies, story drifts and column/beam rotations). Additionally, the dynamic responses of the retrofitted frame were compared to those of the non-retrofitted frame to investigate effectiveness of the retrofit system. The experimental results demonstrate that the retrofit system installed on the first story columns contributed to reducing story drifts and column rotations. Additionally, the retrofit scheme helped mitigate damage concentration on the first story columns as compared to the non-retrofitted frame.