According to the recently revised seismic design standards, seismic design of underground structures is required. Concrete underground outer walls are installed separately from temporary earth retaining walls as permanent underground outer walls. This raises issues of constructability, economy, and space narrowness. Therefore, a steel underground continuous wall is developed to promote construction efficiency, safety, and economy by introducing the off-site construction (OSC) method of underground structures. The steel underground continuous wall will be used as a permanent underground continuous wall along with the temporary earth retaining wall. To this end, it must satisfy structural performance equivalent to or higher than the concrete underground outer wall. The integrity and in-plane shear resistance performance between single panel members must be satisfied to be used as a permanent wall. The interlocking effect through geometric bonding is intended to enhance the bonding effect between these members. Therefore, trapezoidal members were developed, and bending performance tests and analyses of each member were performed to confirm the structural bending performance of these members. The bending performance improvement effect of the combined multiple members was confirmed. As a result, it was confirmed that the integration of members and structural performance was improved due to the interlocking effect of the absence of joints. The seismic design analysis of the demonstration site was performed with these developed members, and it was confirmed that the structural performance was equivalent to or higher than that of the existing RC underground continuous wall. As a result, it was confirmed that the steel underground continuous wall can be used as a permanent underground wall together with the temporary earth retaining wall.

본 연구는 대기 중 장기간 노출로 인해 열화된 Ni-rich NCM811(LiNi₀.₈Co₀.₁Mn₀.₁O₂) 양극 소재의 계면 저항 증가 및 전기화학적 성능 저하 문제를 해결하기 위해, 물리적 열처리 방법을 제안하였다. NCM811 양극 소재는 대기 중 수분 및 이산화탄소와의 반응에 의해 표면에 불순물이 형성되기 쉬우며, 이는 고체전해질과의 계면 저항을 증가시켜 전고 체전지 시스템에서의 성능 저하를 초래한다. 이러한 문제를 해결하기 위해, 열화된 NCM811 양극 소재를 O₂ 분위기 에서 열처리하여 표면의 불순물을 효과적으로 제거하고 양극 표면의 전도성을 향상시킴으로써, 양극-고체전해질 간의 계면 저항을 현저히 감소시키는 결과를 얻었다. SEM, XRD, ICP 분석을 통해 열화된 NCM811 양극 소재의 표면 특성 변화를 분석하였으며, 열처리 후 NCM811 소재의 계면 특성이 개선됨에 따라 전기화학적 성능 또한 상용 NCM811 소재와 유사한 수준으로 회복되는 것을 확인하였다. 특히, O₂ 분위기의 물리적 열처리 방법은 Ni-rich NCM811 양극 소재의 열화를 효과적으로 억제하고 고체전해질과의 계면 접촉을 개선하여, 황화물계 전고체전지의 전기화학적 성능 을 획기적으로 향상시킬 수 있는 유망한 기술임을 입증하였다. 이러한 결과는 전고체전지 상용화를 위한 핵심 전략으 로 적용될 수 있을 것으로 기대된다.

본 연구에서는 강합성라멘교의 벽체 배면 철근 커플러 적용 여부에 따른 두 실험체를 제작하여 하 중가력 실험을 수행하였다. 그 결과 공법에 적용된 주요 기술에 대한 구조적 안전성 및 적정성을 확인 하였으며, 실험체는 설계 내하력 대비 충분한 안전성을 확보하고 있음이 확인되었다. 또한, 경간장 17.3m, 교폭 3.0m, 높이 3.25m의 실험체에 대한 정적성능실험 및 동특성 측정 실험을 수행하였으며, 그 결과 설계 내하력 대비 충분한 안전성을 확보하고 있는 것으로 나타났다.

본 연구는 도로 노면의 결빙을 방지하기 위해 열적 특성을 갖는 콘크리트를 개발했습니다. 팽창 점 토에 상변화 물질(PCM)을 함침 시키고, 고열 전도성 에폭시와 실리카 흄으로 이중코팅을 하여 PCM 물질의 유출 방지, 골재의 부착성 개선, 열적 성능 개선을 하였으며 이를 DSC를 통해 열적 성능 평가 를 진행하여 확인했습니다. 또한 상변화 물질과 경량골재의 사용으로 인한 강도 감소 개선을 위한 CNT 혼합으로 강도 감소를 25% 개선하였습니다.

The paper presents the experimental investigation of RC beams retrofitted with Textile Reinforced Mortar (TRM), featuring enhanced bond capacity. Anchoring systems, including an extension of retrofitting length and the use of chemical anchors, are newly employed to improve the structural performance of the RC beam retrofitted with TRM. For the experimental investigation, a total of seven shear-critical RC beams, with and without stirrups, were designed and constructed. The structural behaviors of specimens retrofitted with the proposed TRM methods were compared to those of non-retrofitted specimens or specimens strengthened with conventional TRM methods. Crack pattern, force-displacement relationship, and absorbed energy were evaluated for each specimen. The experimental results indicate a significant improvement in the shear capacity of the RC beam with the proposed retrofitting method. Therefore, it is concluded that the application of an extended retrofitting length and chemical anchors to the TRM retrofitting method can effectively enhance the bond capacity of TRM, thereby improving the shear performance of RC beams.

아스팔트는 점성이 높은 도로포장 재료로서 골재와 채움재를 결합시키는 역할을 하는 중요한 재료이다. 아스팔트 콘크 리트는 생산 및 시공 과정에서 혼합물이 장비에 부착되는 현상이 발생하여 생산 효율 및 성능 저하를 유발하기도 한다. 이와 같은 문제를 해결하기 위하여 석유류와 식물성 기름을 부착방지제(Asphalt Release Agent)로 사용하고 있다. 하지 만 석유류는 단시간에 아스팔트를 용해시켜 혼합물의 성능 저하를 유발할 수 있고, 발생하는 유증기로 인해 작업자를 위 험에 노출시킬 수 있다. 식물성 기름은 석유류에 비해 아스팔트에 대한 용해력은 다소 작지만 석유류와 동일한 문제를 야기하며 제품 단가로 인해 높은 비용을 발생시킨다. 이에 따라 아스팔트 혼합물 생산 및 시공현장에서 저독성이며 친환 경적인 부착방지제의 중요도가 상승하고 있다.

This paper proposes the armored combat bulldozer, essential for amphibious tasks, requires water ingress prevention and submersion capabilities, typically addressed by a centrifugal pump. This study aims to boost the bulldozer's drainage pump efficiency by replacing the traditional aluminum 3-blade impeller with one made of ASA material using 3D printing. Analysis via ANSYS Fluent revealed that the 5-blade impeller increased discharge volume by 19.31% and efficiency by 6.07%, while the 6-blade variant saw a 27.07% increase in discharge volume and 8.81% efficiency improvement. Further scrutiny with ANSYS Static Structure ensured the new impellers' structural integrity and robustness under extreme conditions. This research confirms the potential of 3D printing in enhancing military equipment, demonstrating significant improvements in pump performance and opening paths for advanced manufacturing techniques to meet the demanding needs of combat vehicles.

In this study, a condensate drain valve was newly installed in the steam inlet pipe line of the soot blower to reduce the amount of condensate contained in the steam for the soot blower. When the economizer is inactive, the condensate drain valve on the soot blower steam inlet pipe line is always opened to drain the condensate. It is intended to reduce environmental pollution and improve economizer performance by reducing the water hammer that inevitably occurs in facilities using steam, and reducing the amount of condensate water generated during the shutdown of the soot blower and the release of soot containing condensate water into the atmosphere when removing soot.

During the initial construction of Won buddhism, the sound absorbing material and diffusion material were used in the interior of the Won buddhism, so the sound performance at each buddhism could not be secured above a certain level, and even in the case of the Won buddhism Bukil dharma hall, the reverberation and volume of the sound generated inside the sanctum was too loud, and since the establishment of the buddhism continued to be dissatisfied, the improvement of the acoustic performance was very urgent. From this perspective, this study measured acoustic performance of the Bukil dharma hall before remodeling, determined the acoustic defects and status, and used acoustic simulation to present three plans for improving acoustic performance. Taking economic feasibility, construction, and construction duration into account, remodeling was performed on the basis of Plan 1 and post-remodeling acoustic performance was measured for comparative analysis of acoustic performance between before and after the improvement. The results of study, before and after sound performance improvement sound pressure level (SPL500Hz) was 71.9dB at 79.4dB , the weighted sound level (SPLdB(A)) was 79.7dB(A) at 89.4dB(A), reverberation time (RT500Hz) was 1.12sec at 1.49sec, early decay time (EDT500Hz) was 1.39sec at 1.63sec, definition (D50,500Hz) was 34.9% at 32.3%, clarity (C80.500Hz) was 1.0dB at –0.4dB, and RASTI was 60.0%(“Good”) at 51.3%(“Fair”) was evaluated. Therefore, the Bukil dharma hall was after remodeling, neither definition(D50) improved notably but excessive volume and reverberation and sound mixing almost disappeared and acoustic performance improved so much that many different events and services could be held.

PURPOSES : The purpose of this study was to improve the performance of concrete pavements by decreasing measurement deviations using an Internet of Things (IoT)-based air content measurement device. METHODS : We calculated the properties of concrete which varied according to the air content. For a low measurement deviation, the concrete pavement performed according to the design standard. To confirm the difference in the performance of the concrete pavement for various air contents, we verified the change in the relative dynamic modulus according to the number of freeze–thaw cycles for each value of the air content. In addition, we analyzed the number of durability cracks according to the freeze–thaw cycles in the field. RESULTS : We confirmed that IoT-based measurement equipment improved the performance of pavements without changing their mixing designs or specifications. We confirmed that the performance of concrete pavements changed even with variations in air content within the range of quality standards. Using IoT-based air content management, we confirmed the reduction in concrete pavement durability cracks without changing the mixing design. CONCLUSIONS : We confirmed that IoT-based air-content management improved pavement performance. The feasibility of extending this concept to manage other concrete properties such as the chloride content should be acknowledged. Future research will require laboratory tests to understand the variation in concrete properties with varying air contents and to consider diverse load conditions.

선박 발전기의 여자기는 출력 단자 전압을 일정하게 유지하기 위하여 여자전류 제어를 통해 자속을 조정한다. 여자기 내부에 있는 전압제어기는 통상적으로 비례 적분 제어방식이 사용되는데 게인과 시정수에 의해 결정되는 응답 특성은 적절치 못한 설정값에 의 해 원하지 않는 출력을 내며 이로 인해 선내 전력의 품질과 안정성을 떨어뜨릴 수 있다. 본 논문에서는 IEEE에서 제공하는 AC4A 타입의 여자기 모델을 통해 얻을 수 있는 안정적인 입출력 데이터를 활용하여 신경망 회로를 학습시킨 후 기존의 비례 적분 제어방식의 전압제 어기를 학습된 신경망 회로 제어기로 대체하여 시뮬레이션을 수행하였다. 그 결과 기존 대비 최대 9.63%까지 오버슈팅이 개선되었으며, 안정적인 응답 특성에 대한 우수성을 확인하였다.

공동주택 방화문의 화재성능 결함으로 인하여 하자소송이 확대되고, 화재발생 시 치명적일수 있다. 그러나 현행 법령은 이에대한 대책이 소홀한 편이다. 본 연구에서는 방화문의 결함과 특성 등을 잘 반영하고 있는 『강제창호 제작･품 질검수 매뉴얼』과 LH 설계･시방서 개정작업에서 드러난 문제점들에 대한 개 선방안을 제시하고자 한다. 방화문의 적정단가를 산정하고 내용연수를 합리적 으로 조정하며 3단계 점검시스템 등 관련규정을 신설 운영한다면, 방화문 품질 성능 향상과 화재시 입주민 보호에 크게 기여할 것으로 판단된다.

PURPOSES : The purpose of this study was to improve the performance of concrete pavements by measuring the unit-water content with an Internet-of-Things (IoT)-based unit-water content measurement device at an increased precision compared with that of existing measuring equipment. METHODS : We calculated the properties of concrete that varied according to variations in the unit-water content. To confirm the change in the performance of concrete pavements, we compared and analyzed the fatigue cracking rate and international roughness index of concrete pavements at the 20-year point of public use according to the changes in properties using the Korea Pavement Research Program(KPRP). RESULTS : We confirmed that IoT-based measurement equipment can improve the performance of pavements without changing their mixing designs or specifications. We confirmed that the performance of the concrete pavements changed significantly, even with unit-water content variations within the range of quality standards. According to IoT-based unit-water content management, we confirmed that the performance of the concrete pavement (fatigue cracking rate and international roughness index) improved without changing the mixing design. CONCLUSIONS : We confirmed that by using IoT-based unit-water content management, pavement performance can be improved. It is necessary to consider whether the application of this concept to other concrete property management items, such as the chloride content, is possible. Considering the changes in concrete properties according to the unit-water content based on laboratory tests and considerations of various load conditions will be necessary for future research.