본 연구는 청소년 부모의 부정적 양육태도, 자아존중감, 부정적 친구관 계가 스마트폰 의존도 및 학업무기력에 미치는 영향을 구조방정식모형을 이용해 분석하고, 스마트폰 의존도의 매개효과를 검증하는 것을 목적으 로 하였다. 이를 위해 한국아동·청소년패널조사2018의 초등학교 4학년 코호트 6차 조사자료(2023년)를 사용하였으며, 중학교 3학년 2,219명을 대상으로 하였다. 분석 결과, 첫째, 부모의 부정적 양육태도, 자아존중감 은 스마트폰 의존도에 유의미한 영향을 미치는 것으로 나타났으며, 부정 적 친구관계는 유의미한 영향을 미치지 않았다. 둘째, 부모의 부정적 양 육태도, 자아존중감, 부정적 친구관계와 스마트폰 의존도는 모두 학업무 기력에 유의미한 영향을 미쳤다. 셋째, 부정적 양육태도와 자아존중감은 스마트폰 의존도를 매개로 학업무기력에 유의미한 영향을 미치는 것으로 확인되었으나, 부정적 친구관계는 스마트폰의존도를 매개로 학업무기력 에 유의미한 영향을 나타내지 않았다. 본 연구는 부모의 양육태도와 자 아존중감이 청소년의 스마트폰 의존도와 학업무기력에 영향을 미치는 것 을 실증적으로 확인하였으며, 특히, 스마트폰 의존도가 학업무기력의 매 개변수로 작용함을 보여주었다. 이러한 결과는 청소년의 스마트폰 의존 도를 완화하고 학업무기력을 줄이기 위해 부모의 양육방식과 청소년의 심리적 특성을 고려한 개입이 필요함을 시사한다.

이 연구는 시설 내 노인학대의 지속적 증가와 구조적 요인에 주목하여, 시설 환경에 서 발생하는 노인학대의 구조적 특성과 교정적 개입 방안을 다각도로 분석하였다. 민･ 형사･행정 판례와 최근 국내외 선행연구를 종합 분석한 결과, 시설 내 노인학대는 인 력 부족, 낮은 근로환경, 조직문화의 결함, 감독 시스템 부재 등 복합적 구조적 요인이 작용함이 확인되었다. 특히 방임, 신체적･정서적･경제적 학대, 성적 학대 등이 반복 적･조직적으로 발생하고 있으며, 신고･처벌 위주의 기존 대응은 실질적 예방과 재발 방지에 한계가 있는 것으로 나타났다. 이에 본 연구는 구조적 개선과 함께, 가해자 대 상 교정적 프로그램 개발, 조직문화 혁신, 직원 교육 강화 등 다양한 정책적･실천적 제언을 제시하였다. 본 연구는 실효성 있는 예방 및 재발 방지 대책 마련에 기초 자료 로 활용될 수 있을 것이다.

During the reign of King Sejong in the Joseon Dynasty (1433-1438), the Daegyupyo (large gnomon) was produced. The Daegyupyo, with a crossbar (horizontal bar), was used to observe the length of the gnomon’s shadow cast by the sun passing at the meridian. The shadow of this crossbar can be obtained using a measurable device called the Yeongbu (shadow definer). These Daegyupyo and Yeongbu are described in detail in the “Treatise on Astronomy” of Yuan History or “Celestial Spheres and Globes” of Jega-Yeoksang-Jjp (Collected Discourses on the Astronomy and Calendrical Science of the Chinese Masters). According to Jega-Yeoksang-Jjp, the Yeongbu had a structure similar to a door attached to its frame. A pinhole is located in the center of a copper leaf corresponding to the door of the Yeongbu. The image of the sun’s meridian transit and the shadow of the crossbar through the pinhole are projected onto the surface of the Daegyupyo’s ruler stone. Unlike the width and length of the Yeongbu, the height of the Yeongbu is not recorded. This research analyzed the height of the Yeongbu required to maintain the constant distance from the pinhole to the ruler stone surface. Based on these assumptions, it was estimated that 8 to 13 Yeongbu of different heights would be needed for observations using the Daegyupyo in Seoul. To accommodate the need for Yeongbu of various heights, this study proposed a model for a stackable Yeongbu with an adjustable height.

This study aimed to evaluate the effects of different feeding levels of domesticated barnyard millet and imported Bermuda hay on the growth performance and structural development of female and male growing goats. A 4×4 Latin square design was used, involving 8 goats with an average age of 3 months: 4 females and males with an initial body weight (BW) of 10.6 kg and 16.0 kg, respectively. Goats were randomly assigned to 4 dietary treatments: T1 (1.5% BW barnyard millet), T2 (1.5% BW Bermuda hay), T3 (2.0% BW barnyard millet), and T4 (2.0% BW Bermuda hay) over a 22-week period. Results indicated that the highest final body weight (FBW) was significantly observed at the highest feeding level (T4), with females reaching 14.9 kg and males 20.9 kg, while the highest average daily gain (ADG) values were recorded for females in T3 at 75.7 g/d and males in T4 at 81.0 g/d (p<0.05). Dry matter intake (DMI) was highest in the T4 group for both females (437.4 g/d) and males (635.9 g/d), with significant differences observed across treatments (p<0.05), whereas the feed conversion ratio (FCR) showed an improving trend, particularly with a value of 6.0 for females in T4. For structural development, the highest feeding levels led to significant increases in body length, body depth, chest width, and chest girth of both sex. Female and male in T4 achieved body lengths of 53.5 cm and 61.8 cm, and body depths of 45.2 cm and 54.8 cm, respectively. Chest width and girth reached 15.9 cm and 66.5 cm in males, and 13.5 cm and 56.5 cm in females. In conclusion, higher feeding levels, especially with Bermuda hay, may positively influence the growth performance and structural development of goats.

이 글은 최근(2020~2023) 발굴된 부소산성 추정 서문지 일원 성벽에 대해 검토한 것이 다. 지금까지 부소산성 성벽 연구는 백제 성벽의 판축 구조물에 집중되었고, 백제~고려시 대 전체 성벽의 변천을 검토해 역사적 의미를 파악하였다. 그러나 부소산에서 가장 중요한 백제 성벽의 구조와 공정에 대한 이해는 여전히 확립되지 못하였다. 이 같은 현황 속에 추정 서문지 일원에서 조사된 포곡식 백제 성벽은 구조와 공정을 파악할 수 있는 자료가 확보되 었고, 백제 멸망 이후에도 통일신라시대까지 사용된 현황이 새롭게 확인 되었다. 먼저, 포곡식 성벽 조사 결과 백제~통일신라 성벽의 축조 공정과 변화가 확인되었다. “1.포곡식 성벽 백제(1~2단계): 1)기반층 정지–2)기저부 조성층–3)성벽(판축·내외 보 강층)–4)성벽 내외시설(1단계 완료)–5)증축시설(2단계)” → “2.포곡식 성벽 통일신라(3~4 단계): 1)1차증축(3단계)-2)2차증축(4단계)” → “3.포곡식 성벽 페성(5단계)”순이다. 그리고, 백제 성벽의 세부 축조 공정은 “1)기반층(원지반) 정지-2)기저부 조성층–3)성벽 조성(①목주용 내·외 구 굴착 및 목주 등 판축 구조물 설치+②내외부 보강층→③체성 판 축→④판축 구조물 해체 및 설치+내외부 보강층+체성 판축 등 2~3회 반복)→4)성벽 내외 시설(내부 석축 배수로, 외부 구상유구)” 순으로 파악된다. 이를 통해 볼 때 백제 성벽 구조 는 “기저부[1)~2)]–체성부[3)]–성벽 내외시설[4)]” 등으로 구분된다. 이 가운데, 곡부구간의 2구역 성벽에서 1·2차 기저부층 중간에 ‘목주용 구와 할석 부 석, 석축암거 및 주변 석축, 체성 하부 다짐 및 외벽 일부 석축’ 등을 시설하여 유수 및 침투 수로부터 붕괴를 막기 위한 수준 높은 작업 공정과 기술이 확인되었다. 그리고, 3구역 판축 성벽 내외벽면에서 점토+기와로 미장(피복) 처리한 현황이 확인되었고, 이를 통해 백제 토 축 성벽의 내외 벽면 마감 방식에 대한 새로운 기법을 파악할 수 있게 되었다.

While the subduction zone earthquakes have long ground motion durations, the effects are also not covered in seismic design provisions. Additionally, the collapse risk of steel frame buildings subjected to long-duration ground motions from subduction earthquakes remains poorly understood. This paper presents the influence of ground motion duration on the collapse risk of steel frame buildings with special concentrically braced frames in chevron configurations. The steel buildings considered in this paper are designed at a site in Seattle, Washington, according to the requirements of modern seismic design provisions in the United States. For this purpose, the nonlinear dynamic analyses employ two sets of spectrally equivalent long and short-duration ground motions. Based on the use of high-fidelity structural models accounting for both geometric and material nonlinearities, the estimated collapse capacity for the modern code-compliant steel frame buildings is, on average, approximately 1.47 times the smaller value when considering long-duration ground motion record, compared to the short-duration counterpart. Due to the sensitivity to destabilizing P-Delta effects of gravity loads, the influence of ground motion duration on collapse risk is more profound for medium-to-high-rise steel frame buildings compared to the low-rise counterparts.

Truss structures, widely used in engineering, consist of straight members transferring axial forces. Traditional analysis methods like FEM and the Force Method become computationally expensive for large-scale and nonlinear problems. Surrogate models using Artificial Neural Networks (ANNs), particularly Physics-Informed Neural Networks (PINNs), offer alternatives but require extensive training data and computational resources. Variational Quantum Algorithms (VQAs) address these challenges by leveraging quantum circuits for optimization with fewer parameters. Variational Quantum Circuits (VQCs) based on Quantum Neural Networks (QNNs) utilize quantum entanglement and superposition to approximate high-dimensional data efficiently, making them suitable for computationally intensive tasks like surrogate modeling in structural analysis. This study applies QNNs to truss analysis using 6-bar and 10-bar planar trusses, assessing their feasibility. Results indicate that residual-based loss functions enable QNNs to make reliable predictions, with increased layers improving accuracy and a higher Q-bit count contributing to performance, albeit marginally.

Automated structural design methods for reinforced concrete (RC) beam members have been widely studied with various techniques to date. Recently, artificial intelligence has been actively applied to various engineering fields. In this study, machine learning (ML) is adopted to make automated structural design model for RC beam members. Among various machine learning methods, a supervised learning was selected. When a supervised learning is applied to development of ML-based prediction model, datasets for training and test are required. Therefore, the datasets for rectangular and t-shaped RC beams was constructed by commercial structural design software of MIDAS. Five supervised learning algorithms, such as Decision Tree (DT), Random Forest (RF), K-Nearest Neighbor (KNN), Artificial Neural Networks (ANN), eXtreme Gradient Boosting (XGBoost) were used to develop the automated structural design model. Design moment (Mu), design shear force (Vu), beam length, uniform load (wu) were used for inputs of structural design model. Width and height of the designed section, diameter of top and bottom bars, number of top and bottom bars, diameter of stirrup bar were selected for outputs of structural design model. Performance evaluation of the developed structural design models was conducted using metrics sush as root mean square error (RMSE), mean square error (MSE), mean absolute error (MAE), and coefficient of determination (R2). This study presented that random forest provides the best structural design results for both rectangular and t-shaped RC beams.

본 연구에서는 상용 폴리염화비닐을 개질하여 두 종류의 PVC 기반 이온교환용 고분자를 성공적으로 제조하였다. 이후 개질된 두 이온교환 고분자를 활용한 전기방사 공정과 열 압착 공정을 거쳐 2차원 계면(2D-PVC-BPM)과 3차원 접합부 (3D-PVC-BPM)를 갖는 바이폴라막(BPM)을 제조하였다. 제조된 3D-PVC-BPM은 2D-PVC-BPM에 비해 우수한 물 분해 효율 및 안정성을 보였다. 구체적으로, 300 mA cm-2의 고전류 밀도에서 3D-PVC-BPM은 2D-PVC-BPM가 나타낸 전위보다 4.4 V 낮은 8.05 V의 막 전위를 나타냈다. 더욱이, PVC 주쇄가 가진 내화학성 덕분에 3D-PVC-BPM은 가혹한 조건에서도 높은 화 학적 안정성을 보였고, 이는 4 M H2SO4 및 4 M NaOH 용액에 28일간 침지한 후 관측된 질량 손실이 각각 2.8%와 2.1%에 그친 것을 통해 입증되었다. 끝으로, 3차원 접합부가 3D-PVC-BPM에 맞물림(interlocking) 효과와 넓은 계면면적을 제공해준 덕분에 3D-PVC-BPM의 인장 강도는 36 MPa를 초과했고 신장률 또한 약 50%에 이르는 등 우수한 기계적 물성을 나타냈다.

이 연구는 다목적 선박(MPV)의 공기역학적 구조물 설계, 분석 및 향상을 통해 그린 워터 압력에 의한 구조적 안전을 보장하고, 탈탄소화 및 에너지 효율성에 이바지하는 방법을 기술하였다. 유한 요소 분석(FEA)을 통한 초기 평가에서 좌굴 발생에 대한 잠재적인 취약점 이 있음을 확인하였다. 이러한 문제를 해결하기 위해 보강재(Carling stiffener)와 두께 증가를 통하여 응력을 재분배하고 국부적인 좌굴 발생의 위험을 최소화하였다. 보강 후 분석 결과, 한국선급(KR)의 안전 기준인 항복 강도, 미국 선급(ABS) 좌굴 강도 및 노르웨이 표준(NORSOK) 변 위 기준을 모두 충족하는 것이 확인되었다. 결과적으로 고유치 좌굴 해석 결과가 안전 기준을 초과하고 최대 변위가 허용 한계 내에 있는 등 중요한 개선이 이루어졌다. 이러한 개선은 극한의 해양 조건에서 운영 신뢰성을 보장할 수 있다. 이 연구는 공기역학적 항력 감소와 구조적 안전성의 이중적인 이점을 강조하며, 국제 해사 기구(IMO)의 2050 탈탄소화 목표에 부합하는 연료 효율성 및 온실가스 배출 감소에 이바지할 수 있다. 연구 결과는 다양한 선박 유형에 걸쳐 항력 감소 기술을 확장하기 위한 기초 자료를 제공하며, 지속 가능하고 탄력적인 해양 운영을 위한 대안을 제시하였다. 향후 연구는 구조적 안전 평가를 가속할 수 있는 단순화된 모델링 기술 개발에 집중할 것이다.

X-ray diffraction is widely used as a non-destructive method for measuring residual stress in crystalline materials, and is particularly useful as a technique for controlling residual stress that has been introduced during the heat treatment or surface treatment of metallic materials. Neutron stress measurement is gaining attention as an internal material measurement method. It complements the demerits of the X-ray method in that it measures stress in a very thin surface layer. The neutron stress measurement method, like the X-ray method, is based on the principle of crystal diffraction, and its penetration depth is about 1,000 times greater than that of the X-ray method and is suitable for measuring the inside of a material. This study investigated the residual stress measurement method using the sin2ψ method using shot-peened mechanical structural carbon steel. The non-destructive measurement using high-energy X-rays was compared with the residual stress measured using conventional laboratory X-rays, and the following results were obtained. The high intensity diffraction angles using highenergy X-rays are low, but can be measured with sufficient precision. Interpreting the three diffractions 633, 552, and 721 as a single diffraction profile allowed stress measurements to be made, and the calculated value was close to the weighted average of the intensity ratios. The results of the high-energy X-ray residual stress measurements were in good agreement with the results from laboratory X-rays, confirming the usefulness of this method as a non-destructive method of assessing stress deep inside materials.

The rotary type dust remover is a device in which the rake assembly filters and processes clumps in the water while rotating and repeating movements along the track. It is installed in the pump suction part of the drainage pump station and the rainwater pump station to protect the pump to ensure smooth drainage. Since the rake assembly plays a key role in filtering out complications while passing through the water, stainless steel is applied to all components constituting it, and damage or failure due to deformation causes a crisis in case of heavy rain. This is because the existing rake assembly is excellent in rigidity, but all components are assembled by welding, which takes a lot of time for repair and replacement. In this study, shape design for rakes and assemblies of the rotary type dust remover, structural analysis to secure reliability, and demonstration tests were conducted through prototype production. Through this, it is intended to help prevent the stiffness of the joint of the rotary type dust remover from deteriorating, reduce time and cost, and efficient operation.

This study analyzes the aerodynamic and structural characteristics of an H-Darrieus vertical-axis wind turbine (VAWT) under varying inlet velocities using transient analysis. The k-ε turbulence model and six-DOF were applied to simulate urban environments in the flow analysis, while the structural analysis considered blade momentum of inertia and RPM conditions. The numerical results showed that the drag and lift forces increased by 60% and 53% respectively from the nominal wind speed to the cut-off wind speed conditions. Structural analysis indicated that the maximum Von-Mises stress in the blade did not exceed the yield strength of 69 MPa of PC-ABS, ensuring structural stability. However, the connecting rod exceeded the yield strength of SPCC 270 MPa, suggesting potential failure due to repeated rotational loads. This study confirms that materials with a yield strength of more than 1,100 MPa required for connecting rods to ensure reliable operation at high wind speed. These findings provide important insights for the design of robust VAWTs suitable for extreme environments.

In this paper, the design feasibility of the high-temperature rotation test jig for the operating state of gas turbine blades was confirmed through thermal structural analysis and modal analysis. The structural analysis model was composed of assembled blade, disc, cover, and shaft. Here, the disc was designed to be assembled with two types of blade. First, thermal analysis was performed by applying the blade surface temperature of 800°C. Next, structural analysis was performed at 3600 RPM, the normal operating condition, and 4320 RPM, the overspeed operation condition. Lastly, modal analysis was performed to examine the natural frequency and deformation of the jig. The FE analysis showed that the temperature decreased from the blade to disc dovetail. Additionally, both the blade and disc showed structural stability as the maximum stress was below the yield strength. Also, the first natural frequency was 636.35Hz and 639.43Hz at 3600RPM and 4320RPM, respectively, satisfying gas turbine design standards and guidelines. Ultimately, the designed test jig was confirmed to be capable of high temperature and rotation testing of various blades.

Piloti-type buildings are widely constructed in urban areas of South Korea. Due to stiffness irregularities, piloti-type buildings are vulnerable to lateral loads such as earthquakes. Although seismic retrofitting is necessary for piloti-type buildings, many of these structures are privately owned, and the extensive number of buildings creates significant challenges in terms of cost and time for regional seismic performance evaluation. This study proposes a methodology for determining the seismic performance of multiple piloti-type buildings within a region by utilizing structural parameters. Information on piloti-type buildings is classified into public building data and exterior building data, which are integrated to define structural parameters for estimating the first natural period of the buildings. Linear regression analysis was performed to develop a regression equation correlating structural parameters with the natural period. Additionally, the natural period and structural parameters are used to perform another linear regression analysis to estimate the yield and ultimate points of the capacity curve. The capacity curves derived from the regression equations facilitate seismic performance evaluation based on structural parameters.

The green supply chain has become a central concern for global businesses, particularly in maritime industries, where sustainable development is pursued as both an economic growth strategy and a means of environmental preservation. This study seeks to identify the key challenges to implementing green supply chain in Vietnam. The Analytical Hierarchy Process (AHP) is employed to assess the significance of various factors, while Fuzzy Structural Modeling (FSM) is used to explore their interrelationships. Five major factors - economic, technological, organizational, governmental, and social - are identified as critical to the implementation of green supply chain. The study highlights that the organizational factor is the most crucial, with customer pressure, particularly regarding environmental standards from export countries, being the most influential sub-factor. The findings provide important insights for developing government policies, offering support to businesses, and guiding investment decisions in green supply chain.

This study investigates the structural stability of a telescopic arm designed for a painting robot through finite element analysis (FEA). As factory automation progresses, robots are increasingly used to replace hazardous tasks like painting. However, the heavy weight of telescopic arms poses significant control challenges. This research specifically examines the structural stability of a 7.4-meter telescopic arm, designed for use in a 14m x 14m large-scale block painting environment. The telescopic arm consists of six steel links, each ranging from 700 mm to 1500 mm, and supports a 50 kg painting robot mounted at the end of Link 6. Using Dassault System’s Abaqus2022 software, simulations were performed in both stretched and rotated modes to analyze self-weight effects and structural stability. The results revealed maximum deflection of 92.3 mm in stretched mode and 127.3 mm in rotated mode, with the highest stress concentration of 416.8 MPa occurring at the Link 3 and Link 4 connection. To improve stability, additional reinforcement materials and an increase in connector thickness from 40 mm to 80 mm were applied, successfully reducing maximum stress to 94.3 MPa. These findings suggest an effective enhancement in the stability of the telescopic arm under various operational modes.

In order to revitalize the marine leisure industry, researches on various leisure vessels have been widely conducted in Korea. In particular, in the field of leisure sports, researches and developments for improving the performance of high-speed motorboats are actively progressing. For reducing the weight of motorboats various composite materials are applied to the hull, and these composite materials must ensure structural safety. In this study, the material properties of composite materials applied to tunnel-type motorboats, used in the OSY(Outboard Stock Yamato)-400 race, were evaluated and the structural analysis was performed to examine the safety of the motorboat hull. Material tests were conducted according to Korean Industrial Standard and structural analysis of finite elements model of the motorboat hull was performed under longitudinal bending and torsional load conditions, respectively. By comparing the analysis results with the material test results, it was confirmed that the applied composite material meets the required strength.

본 연구는 275명의 대학생을 대상으로 AI 프로그램에 대한 인식과 활 용 간의 구조적 관계를 분석하였다. 연구 방법으로는 설문 조사를 통해 AI 프로그램의 유용성, 신뢰성, 사용 빈도, 만족도를 측정하였으며, 구조 방정식 모델(SEM)을 이용해 변수 간의 관계를 분석하였다. 그 결과, 유 용성 인식이 높을수록 AI 프로그램 활용 빈도와 만족도가 증가하는 반 면, 신뢰성 인식이 낮을수록 사용 빈도와 만족도가 감소하는 경향을 확 인하였다. 이러한 결과는 AI 프로그램을 학습 도구로 효과적으로 통합하 기 위해서는 신뢰성을 높이고 사용 편의성을 개선하는 것이 중요하다는 점을 시사한다. 본 연구는 대학생들의 학습에서 AI 프로그램의 역할을 체계적으로 분석하고, AI 기술의 교육적 활용 방안을 제시한다.