A Catholic school is a school that spreads religious ideology to students by combining religious education with regular school curriculum. But, most Catholic schools do not have a separate liturgical space, mass is performed in multipurpose spaces such as auditoriums, and are exposed to severe acoustic defects due to the very aging facilities and lack of sound performance suitable for the liturgical space. So, in this study, an improvement plan was proposed using sound simulation after identifying acoustic defects through field measurements in the liturgical space of Haeseong High School in Jeonju. Also, hearing experiment using Acoustic Psychological Analysis was conducted to identify changes in subjective responses felt by students as they improved their acoustic performance. The results of study, before and after sound performance improvement sound pressure level (SPL500Hz) was 64.8dB at 66.7dB, the weighted sound level (SPLdB(A)) was 67.9dB(A) at 75.8dB(A), reverberation time (RT500Hz) was 2.04sec at 2.52sec, definition (D50,500Hz) was 40.2% at 33.5%, clarity (C80.500Hz) was –0.8dB at –1.18dB, and RASTI was 57.7% at 49.2% was evaluated. In addition, the amount of improvement in subjective responses before and after sound performance through psycho-acoustic experiment decreased by “Reverberation” -17.0%, “Loudness” -11.3% and increased by “Clear” 21.3%, “Vivid” 21.3%, “Intimacy” 12.4%, “Warmth” 14.3%, “Stability” 19.3%, “Godliness” 18.8%. Therefore, after improving sound performance, Haesung High School's liturgical space improved satisfaction with subjective sound performance felt by students and teachers to ensure sound performance suitable for the liturgical space.

The railroad facilities are intended for long-term operation as the initial acquisition costs necessary for infrastructure construction are high. Therefore, regular maintenance of railroad facilities is essential, and furthermore, system reliability through systematic performance evaluation is required. In this study, the signal control system of railroad electrical equipment was selected as the subject of research and the performance evaluation target facility selection study was conducted using AHP. The results of the study can contribute to the reliability of the signal control system as well as to the reliability of the railroad system, which is a higher system.

In this study, a motion control problem for the vessel towed by towing ship on the sea is considered. The towed vessel does not have self-control capabilities such that its course stability totally depends on the towing ship. Especially, in the narrow canal, river and congested harbor area, extreme tension is required during the towing operation. The authors, therefore, propose a new control system design method in which the rudder is activated to provide its maneuverability. Based on the leader following system configuration, a nonlinear mathematical model is derived and a backstepping control is designed. By experiment results with nonlinear control framework, the usefulness and effectiveness of the proposed strategy are presented.

In a previous paper, ambient vibration tests were conducted on a cable stayed bridge with resilient-friction base isolation systems (R-FBI) to extract the dynamic characteristics of the bridge and compare the results with a seismic analysis model. In this paper, a nonlinear seismic analysis model was established for analysis of the bridge to compare the difference in seismic responses between nonlinear time history analysis and multi-mode spectral analysis methods in the seismic design phase of cable supported bridges. Through these studies, it was confirmed that the seismic design procedures of the “Korean Highway Bridge Design Code (Limit State Design) for Cable Supported Bridges” is not suitable for cable supported bridges installed with R-FBI. Therefore, to reflect the actual dynamic characteristics of the R-FBI installed on cable-supported bridges, an improved seismic design procedure is proposed that applies the seismic analysis method differently depending on the seismic isolation effect of the R-FBI for each seismic performance level.

In this study, a field bridge test was conducted to find the dynamic properties of cable supported bridges with resilient-friction base isolation systems (R-FBI). Various ambient vibration tests were performed to estimate dynamic properties of a test bridge using trucks in a non-transportation state before opening of the bridge and by ordinary traffic loadings about one year later after opening of the bridge. The dynamic properties found from the results of the tests were compared with an analysis model. From the result of the ambient vibration tests of the cable supported bridge with R-FBI, it was confirmed that the dynamic properties were sensitive to the stiffness of the R-FBI in the bridge, and the seismic analysis model of the test bridge using the effective stiffness of the R-FBI was insufficient for reflecting the dynamic behavior of the bridge. In the case of cable supported bridges, the seismic design must follow the “Korean Highway Bridge Design Code (Limit State Design) for Cable supported bridges.” Therefore, in order to reflect the actual behavior characteristics of the R-FBI installed on cable-supported bridges, an improved seismic design procedure should be proposed.

In this study, optimizations were carried out for a heater core and an evaporator installed in a passenger car. The main geometric parameters of each component were selected as design variables, and the main performances examined were the outlet temperature and the pressure drop. In addition, the sensitivity analysis was performed to grasp the dominant design variable. The thermal flow analysis for each component was performed using the commercial program STAR CCM+. On the other hand, EasyDesign, a commercial program based on DOE and metamodel-based optimization, was used as an optimization tool. The optimized performances of the heater core were compared with performance target, and finally, the improved designs of the heater and the evaporator were presented.

본 연구는 고추수확기의 이물질 선별부의 선별성능을 분석하기 위해 수행하였다. 고추 품종 3가지에 대하여 건조하지 않은 시료와 건조한 시료의 고추 과실 및 이물질의 부유 속도를 측정하였다. 각 시료의 부유 속도를 측정한 결과, 건조하지 않은 고추 과실, 고추 줄기, 고춧잎은 각각 11.5-14.3 m/s, 10.9-12.5 m/s, 3.45-5.42 m/s 로 나타났다. 건조한 고추 과실, 고추 줄기, 고춧잎의 부유속도는 각각 10.89-12.1 m/s, 8.35-9.54 m/s, 2.74-5.14 m/s로 나타났다. 이물질 선별부 요인 실험 장치를 제작하고, 풍향 가이드 3개, 5개를 추가한 풍구를 제작하여 풍향 가이드 추가에 따른 풍속을 측정하였으 며 그 결과, 풍향 가이드 추가한 풍구의 좌우 풍속의 편차가 풍향 가이드를 추가하지 않은 풍구의 풍속 편차보다 낮았다. 풍구 가이드의 갯수와 수집 가이드의 위치에 따라 이물질 선별률, 이물질 정체율을 조사하고, 그 결과를 반복이 있는 이원배치법을 사용하여 통계분석을 실시하였다. 수집 가이드 위치를 전방 중앙 기준으로 풍향 가이드를 추가하지 않은 풍구 이물질 선별률과 이물질 정체율은 각각 47.0%, 7.2%로 나타났다. 풍향 가이드를 3개 추가한 경우 이물질 선별율과 정체율은 각각 34.2%, 2.6% 였으며, 풍향 가이드 5개를 추가한 경우 각각 31.1%, 0.8%로 나타났다. 이물질 선별 및 정체를 고려하였을 때 풍향 가이드 3개를 추가하고 수집 가이드 위치를 전방 중앙 조건에서 최적인 조건으로 판단된다.

목적 : 본 연구는 비정시 군인에게 지급되는 military goggle 및 insert frame의 특성을 비교하고, 결합 상태에 서 발생 가능한 시각적 문제점을 분석하였다. 발견된 시각적 문제점을 해결하기 위해 multi-function unit(MFU) insert frame을 제작했다. 이를 통해 비정시 군인의 시력 향상에 기여하고자 하였다. 방법 : Military goggle에 조합시키기 전·후 insert frame의 크기(렌즈삽입부, 연결부 및 전면부, 정정간거 리)와 각도(안면각 및 경사각)을 측정했다. 3D 스캐닝과 프린팅을 통해 바이오레진 재질의 MFU insert frame을 제작했다. 또한, 평균 연령 21.08±0.89세의 비정시 군인 37명을 대상으로 고대비 및 저대비 교정시력과 주관적 만족도를 조사했다. 결과 : 조합된 상태의 insert frame은 MFU insert frame에 비해 정점간거리, 안면각 및 경사각에서 각각 18.17±0.24 mm, 20.17±0.24°, 10.17±0.24°로 더 큰 것으로 나타났다. 전반적 만족도는 MFU insert frame (3.30±1.22 points)이 insert frame(2.24±1.09 points)에 비해 높은 것으로 나타났으며, 통계적으로 유의한 차이가 발견되었다(p＜0.050). 결론 : 본 연구에서 제작된 MFU insert frame은 비정시 군인의 시력 및 시각적 만족도를 향상시킬 것으로 생 각된다.

본 연구는 기존에 사용하여 왔고, 최근에 온습도의 정확도를 검증하였던 강제 흡출식 복사선 차폐장치(Aspirated Radiation Shield; ARS)를 이용하여 모 기업(A 회사)에서 개발한 시스템의 성능을 개선하고, ARS 장치의 풍속이 온습도에 미치는 영향에 대해서도 시험적으로 검토하였다. 그 결과를 요약하면 다음과 같다. A 회사 제품의 시스템을 개선하기 전, A 회사 시스템의 온도는 ARS 장치로 측정한 온도보다 최대 10.2℃정도 높았고, 상대습도는 20.0%정도 낮게 나타났다. 시스템을 개선한 후, 노드 1, 2의 온도 및 상대습도는 거의 일치하는 것으로 나타났다. 개선 후의 노드 2와 ARS 장치로 측정한 온도간의 최고, 평균 및 최저온도를 포함한 온도편차는 각각 0.2～0.7℃정도로써 ARS 장치가 약간 낮거나 높게 나타나는 경향이 있었다. 상대습도의 경우, 일몰 직후 ARS 장치의 상대습도가 약 10.0%정도 높게 나타나는 경향이 있었지만, 그 이외에는 평균적으로 1.9%정도 ARS 장치가 약간 낮게 나타나는 경향이 있었다. 그리고 노드 1을 최소-중간 사이, 중간-최대 사이 및 최대로 설정한 경우, 노드 1, 2의 최고, 평균 및 최저온도를 포함한 편차는 각각 0.1～0.4℃, 0.0～0.2℃ 및 0.0～0.5℃정도였다. 그리고 노드 1의 3개 측점과 ARS 장치의 최고, 평균 및 최저온도를 포함한 편차는 각각 0.2～0.5℃, 0.1～2.2℃ 및 0.1～1.1℃정도의 범위로써 풍속의 크기에 따른 온도편차는 아주 미미한 것으로 나타났다. 또한 선행연구 및 본 연구의 결과를 종합하여 보면, 온도오차를 개선하기 위한 적정 풍속은 1.0～2.0m·s-1 정도의 범위일 것으로 판단되었다.

Gas burner has been widely utilized to many industrial fields and personal outdoor activities and so on. Portable small-sized gas burner is, especially, useful in personal outdoor activities. The performance and safety of portable small-sized gas burner is important because it uses gas as fuel. The purpose of this study was to investigate the possibilities of performance improvement of portable small-sized gas burner through flow and structural analysis, respectively. As the results, it showed that mass fraction of butane gas in all cases(Type 1, Type 2, Type 3) was about 12~18% and further safety load of 3 stand leg was below 10 kgf.

Recently, blockchain technology has been recognized as one of the most important issues for the 4th Industrial Revolution which can be represented by Artificial Intelligence and Internet of Things. Cryptocurrency, named Bitcoin, was the first successful implementation of blockchain, and it triggered the emergence of various cryptocurrencies. In addition, blockchain technology has been applied to various applications such as finance, healthcare, manufacturing, logistics as well as public services. Distributed consensus algorithm is an essential component in blockchain, and it enables all nodes belonging to blockchain network to make an agreement, which means all nodes have the same information. For example, Bitcoin uses a consensus algorithm called Proof-of-Work (PoW) that gives possession of block generation based on the computational volume committed by nodes. However, energy consumption for block generation in PoW has drastically increased due to the growth of computational performance to prove the possession of block. Although many other distributed consensus algorithms including Proof-of-Stake are suggested, they have their own advantages and limitations, and new research works should be proposed to overcome these limitations. For doing this, above all things, we need to establish an evaluation method existing distributed consensus algorithms. Based on this motivation, in this work, we suggest and analyze assessment items by classifying them as efficiency and safety perspectives for investigating existing distributed consensus algorithms. Furthermore, we suggest new assessment criteria and their implementation methods, which can be used for a baseline for improving performance of existing distributed consensus algorithms and designing new consensus algorithm in future.