https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/167 2026-07-04T00:45:08Z https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/212898 Title: Physical interaction pressure between wearers and back exoskeletons during repetitive lifting Authors: Lei, Ting; Heung, Kelvin Holam; Seo, Joon Oh; Kim, Hyunsoo Abstract: Lower back pain is a widespread occupational hazard among construction workers, causing health and economic burdens. Industrial back exoskeletons provide support to reduce spinal strain, but excessive interaction pressures-the localized contact pressures between wearer and device-limit applicability. This study quantifies interaction pressure magnitude and distribution for four back exoskeletons (Laevo FLEX, IX BACK, SV Exosuit, Laevo V2.5) during controlled repetitive lifting representative of construction tasks. Pressure sensors recorded at upper body (chest for Laevo V2.5; shoulder for others), thigh, and lateral waist (excluding SV Exosuit). Lightweight active SV Exosuit produced the lowest standing pressures. Waist belts offload thigh pressures and enhance stability but create high localized pressures and shift torque to the waist. Chest interfaces distribute loads yet can restrict breathing and cause fit issues. Thigh comfort depends on pad size, strap design, and waist configuration. Findings identify design trade-offs and guide targeted optimizations to reduce pressures and improve comfort. 2026-09-01T00:00:00Z https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/213278 Title: Comparative assessment of hexavalent chromium (Cr(VI)) immobilization in cement pastes with copper, steel, granulated blast-furnace, and ferronickel slags Authors: Kim, Gyeongryul; Sim, Sungwon; Cho, Seongmin; Jee, Hyeonseok; Kim, Min Kyoung; Kwon, Seung-Jun; Bae, Sungchul Abstract: Hexavalent chromium (Cr(VI)) is a highly toxic and mobile contaminant that requires effective stabilization in cement-based waste treatment systems. This study comparatively evaluates the Cr(VI) immobilization behavior of cement pastes incorporating four metallurgical slags: copper slag (CS), steel slag (SS), ground granulated blast-furnace slag (GGBFS), and ferronickel slag (FNS), with focus on chemistry-controlled mechanisms. Cr(VI) was introduced in the form of K2CrO4, and immobilization characteristics were examined through phase analysis, spectroscopic techniques, and leaching tests. The results indicate that CaO-rich slags promote the formation of Cr-bearing phases, including CaCrO4, CrO4-substituted AFt/AFm phases, and calcium (alumino)silicate hydrates, which contribute to chromate retention and partial reduction to Cr(III). In contrast, MgO-rich FNS limits the development of key hydrate phases and shows lower stabilization performance despite comparable strength. Phase quantification and chromium valence analysis show consistent agreement with leaching behavior, suggesting that hydrate assemblage and calcium availability play a more decisive role than mechanical performance in governing immobilization efficiency. Toxicity characteristic leaching procedure (TCLP) results confirm higher Cr(VI) retention in CaO-rich slag (SS and GGBFS) systems compared with CaO-deficient slags (CS and FNS), as well as 100% cement paste. These findings provide mechanistic insight into chromium stabilization in cementitious matrices and support the use of selected industrial slags as alternative low-carbon binders for hazardous waste immobilization. 2026-08-01T00:00:00Z https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/212327 Title: Reactivity contrast between hydrated and dehydrated cement pastes under alkali activation: Roles in gel evolution and compressive strength Authors: Park, Jaeyeon; Im, Sumin; Cho, Seongmin; Sim, Sungwon; Bae, Sungchul Abstract: This study evaluates the feasibility of recycling dehydrated cement paste (DCP) as a reactive calcium silicate source in fly ash-based alkali-activated materials (AAMs) and elucidates temperature-dependent phase evolution and gel chemistry. The performance of DCP was compared with that of hydrated cement paste and ordinary Portland cement under curing conditions of 25 °C and 60 °C. At 25 °C, the incorporation of DCP, containing residual C–S–H, promoted the early formation of C–(N)–S–H gel and improved initial strength via exothermic reactions. At 60 °C, the dissolution of both DCP and FA was significantly accelerated, leading to rapid phase evolution and substantially increased strength. Under these hydrothermal conditions, cancrinite was formed and subsequently transformed into C–(A)–S–H-type gel through ion-exchange and structural reorganization processes. These transformations were confirmed by X-ray diffraction, solid-state Si and Al nuclear magnetic resonance, and FE-SEM/EDS analyses. The results demonstrate that DCP acts not only as a reactive calcium source but also as a kinetic modifier that enhances both the reactivity and strength development of FA-based AAMs. This study provides new insight into the temperature-dependent behavior of recycled cementitious fines and demonstrates their potential as sustainable binder components. 2026-07-01T00:00:00Z https://scholarworks.bwise.kr/hanyang/handle/2021.sw.hanyang/217635 Title: Enhancing Retrieval-Augmented Generation Performance through Network Analysis of Question Types in Public Procurement Law Authors: Lee, Kyung-Tae; Im, Jin-Bin; Hong, Rong-Lu; Kim, Ju-Hyung Abstract: Public procurement and construction contracts underpin national industries; however, their complex legal frameworks and the engagement of multiple stakeholders frequently produce interpretive difficulties and disputes. Small- and medium-sized specialty contractors are particularly disadvantaged by their limited access to legal information, sparking interest in generative AI systems for statutory interpretation and contract support. However, these systems pose risks of factual errors and legal misinterpretations due to hallucinations. To mitigate these limitations, retrieval-augmented generation (RAG)–based question answering has been investigated to evaluate the reliability and efficiency of AI outputs, yet systematic analyses of legal taxonomies and the effectiveness of different question types remain scarce. This study developed a classification of the interrelationships between statutes and contracts in public procurement and conducted literature and network analyses on the Republic of Korea’s Act on Contracts to Which the State is a Party and the Standard Construction Contract. The study adopts a six-part framework comprising (1) core values and definitions; (2) documents and forms; (3) stakeholders; (4) procurement and performance; (5) special clauses; and (6) dispute-related provisions. Using this framework, a GPT-4o–driven RAG system was implemented for question-answering experiments. The accuracy by question type was evaluated using the cosine similarity between the generated answers and reference responses. The results indicate higher accuracy for conceptual queries (e.g., definitions and principles), whereas items requiring procedural or composite interpretation perform comparatively worse, empirically demonstrating that AI answer quality is directly shaped by query structure and context design. By systematizing the structural linkages between statutes and contracts through a framework and empirically validating RAG-enabled legal Q&A performance with an emphasis on question types, this study outlines a pathway to knowledge-structure standardization that supports digital transformation in public procurement and mitigates legal risk in research and practice. 2026-07-01T00:00:00Z