Gate valves are hydraulic components used to shut-off the water flow in water distribution systems. Gate valves may fail owing to various aspects such as leakage through seats, wearing of packing, and corrosion. Because it is considerably challenging to detect valve malfunctioning until the operator identifies a significant fault, failure of the gate valve may lead to a severe accident event associated with water distribution systems. In this study, we proposed a methodology to diagnose the faults of gate valves. To measure the pressure difference across a gate valve, two pressure transducers were installed before and after the gate valve in a pilot-scaled water distribution system. The obtained time-series pressure difference data were analyzed using a machine learning algorithm to diagnose faults. The validation of whether the flow rate of the pipeline can be predicted based on the pressure difference between the upstream and downstream sides of the valve was also performed.

Black carbon (BC), which is mainly contained in fine particulate matters, is one of the typical anthropogenic air pollutants that are generated from the incomplete combustion process and discharged into the atmosphere, and its various health effects particularly on children have been a growing concern. In this study, BC and particulate matters were closely analyzed in an elementary school adjacent to a high- traffic road in a large metropolitan city. The investigation showed that black carbon behaved similarly to ultrafine dust of 0.3 μm or less in the air, accounting for 20%-40% of it. The occurrence of high concentration outdoor pollution influences the BC content in indoor particulate matters. The average I/O value was 0.7 during the class-hours, and 0.8 without students. However, when students played in the classroom, the range of BC concentrations varied from 0.25 to 1.15, wider than 0.41-1.13 without students. Although this study was conducted with regard to just one elementary school, it can be considered to represent the typical air quality status of domestic schools, and it is believed to present valuable data which can be utilized to assist with preparing measures to enhance the air quality management of schools.

목적 : 멀티포컬 콘택트렌즈(MFCL) 착용 시 시각 피질에서 발생하는 ERP 변화를 확인하기 위하여 단초점 콘택트렌즈 착용 시 나타나는 ERP 변화와 비교하였다. 방법 : 안질환이 없는 근시안 20명 (여성 15명, 남성 5명, 평균 연령 24.00±0.51세)을 대상으로 하였으며, 단안 시력 0.00 logMAR 이하, -0.75 D 이상의 난시안, 0.50 D 이상의 부등시안, 조절력이 비정상적이거나 시력교정술을 받은 경우는 제외하였다. 단초점 콘택트렌즈(SVCL)와 낮은 가입도 중심부-근용 멀티포컬 콘택트렌즈를착용시킨 후 NeuroScan SynAmps 2 프로그램을 이용하여 시피질에서 일어나는 시각반응을 ERP로 기록하였다. P100 분석은 O1, O2 채널을 사용하고, N170 분석은 P7, PO7, P8 및 PO8 채널을 사용하였다. MFCL 착용 후 나타난 P100과 N170의 활성도(amplitude)와 반응시간(latency)은 SVCL 착용 후 나타난 값과 비교하였다. 결과 : MFCL 착용 시 단안과 양안에서의 P100 활성도는 SVCL 착용 시와 차이가 없었으나 P100 반응시간은 우세안에서 SVCL 착용 상태보다 길었다(p=0.036). MFCL 착용 시 우세안의 N170 활성도는 비우세안보다 작았고(p=0.001), 비우세안은 단초점 콘택트렌즈 착용 시보다 작았다(p=0.008). 그러나 양안에서 N170 활성도와 반응시간은 SVCL 착용 상태와 차이를 보이지 않았다(p=0.200), (p=0.249). 결론 : MFCL 착용 후 초기시각반응과 인식과정은 우세안에서는 저하되었지만, 양안 상태에서는 SVCL 착용시와 차이가 없었다. 따라서 MFCL 착용 후 나타나는 망막에 맺힌 흐린 상은 양안 융합과정에서 극복되어 시기능에 영향을 주지 않는 것으로 사료된다.

We introduce the Transformable Reflective Telescope (TRT) kit that applies an aluminum profile as a base plate for precise, stable, and lightweight optical system. It has been utilized for optical surface measurements, developing alignment and baffle systems, observing celestial objects, and various educational purposes through Research & Education projects. We upgraded the TRT kit using the aluminum profile and truss and isogrid structures for a high-end optical test device that can be used for prototyping of precision telescopes or satellite optical systems. Thanks to the substantial aluminum profile and lightweight design, mechanical deformation by self-weight is reduced to maximum 67.5 μm, which is an acceptable misalignment error compared to its tolerance limits. From the analysis results of non-linear vibration simulations, we have verified that the kit survives in harsh vibration environments. The primary mirror and secondary mirror modules are precisely aligned within 50 μm positioning error using the high accuracy surface finished aluminum profile and optomechanical parts. The cross laser module helps to align the secondary mirror to fine-tune the optical system. The TRT kit with the precision aluminum mirror guarantees high quality optical performance of 5.53 μm Full Width at Half Maximum (FWHM) at the field center.

Even in an era where 8-meter class telescopes are common, small telescopes are considered very valuable research facilities since they are available for rapid follow-up or long term monitoring observations. To maximize the usefulness of small telescopes in Korea, we established the SomangNet, a network of 0.4{1.0 m class optical telescopes operated by Korean institutions, in 2020. Here, we give an overview of the project, describing the current participating telescopes, its scientic scope and operation mode, and the prospects for future activities. SomangNet currently includes 10 telescopes that are located in Australia, USA, and Chile as well as in Korea. The operation of many of these telescopes currently relies on operators, and we plan to upgrade them for remote or robotic operation. The latest SomangNet science projects include monitoring and follow-up observational studies of galaxies, supernovae, active galactic nuclei, symbiotic stars, solar system objects, neutrino/gravitational-wave sources, and exoplanets.