The turbine wheel plays a crucial role in operating turbines, and with recent advancements in technology, the performance requirements for turbine wheels have significantly increased. Consequently, it is essential to predict failure speeds, as turbine wheels must maintain high stability and reliability under harsh operating conditions. In this study, only the centrifugal loads generated by rotati were considered, excluding conditions such as temperature and pressure. A round-shaped fuse section was applied to the turbine wheel, and the stresses induced by variations in shape were analyzed to predict failure speeds. The results obtained using the Hallinan criteria were compared with the results from finite element analysis (FEA) to validate the predicted failure speeds, showing good agreement between the two methods.

This study aims to calculate the passenger car equivalent (PCE) of heavy vehicles on one-lane exit sections of underground roads. Traffic-flow simulations were performed using the VISSIM software program. The scenarios were designed under varying conditions, including design speeds of 40 and 50 km/h, slope gradients ranging from 3% to 9%, and heavy vehicle proportions between 5% and 40%. The mixed-traffic flow capacity was calculated for each scenario at the threshold levels, and the PCE was estimated based on the two capacity conditions. The results revealed that the PCE decreased at lower design speeds. For slopes less than 6% at a design speed of 40 km/h, and for slopes less than 4% at 50 km/h, the PCE remained consistent across all conditions. Single-lane exit sections are often employed on underground roads because of congestion and structural constraints. However, when heavy vehicles are present in these sections, the overall traffic flow is dictated by the speeds of the heavy vehicles. To address this issue, the implementation of variable or temporary two-lane exit sections has been proposed to enhance traffic flow and capacity.

The purpose of this study was to optimize the design of asphalt concrete pavements for Jeju Island by considering the regional characteristics of the island. This study employed an MEPDG program to determine the allowable traffic loads for class 4 vehicles by considering the axle loads, climate, and material properties. Samples of basalt asphalt concrete from Jeju were used to measure the dynamic modulus for material property estimation. The climate input was based on 30-year climate data from Jeju. The thicknesses and moduli of the subgrade, subbase, and asphalt layers were incorporated into the design. The regression-analysis program SPSS was used to develop a regression equation for the overlay design, factoring in the modulus and thickness ratios between the existing and overlay asphalt layers. A pavement-thickness design formula tailored to Jeju's characteristics was derived. An equivalent single-axle load factor (ESALF) formula was developed to facilitate traffic-load estimation for different roads, enabling the easy incorporation of varying traffic volumes into the design. The ESALF formula demonstrated a high correlation with the pavement thickness, subgrade conditions, and axle loads, whereas the pavementthickness design formula exhibited strong correlations with the pavement thickness, subgrade state, thickness ratios, and modulus ratios. The use of basalt aggregates in asphalt concrete pavements provides an economically viable and technically sound solution for Jeju. The proposed design methodology not only reduces costs but also enhances pavement performance and road safety. The developed formulas offer flexibility in adjusting designs based on specific traffic conditions, providing optimal pavement solutions for different road categories.

정온한 생활환경의 보전과 국민 건강의 보호를 위해 소음에 대한 환경기준을 환경정책기본법에 따라 일반지역과 도로변지역으로 구 분하여 관리하고 있다. 그 중 도로변지역에 있는 주거지역은 주간시간대 65 dBA, 야간시간대 55 dB 이하로 환경소음을 관리하여야 한 다. 그러나, 심화된 도시화에 따라 주거건축물의 밀도는 보다 높아지고, 도심 내 간선도로의 고속화로 주거지역에 대한 도로소음의 영 향이 증가되어가고 있다. 소음진동관리법에서는 방음시설의 설치 등의 조치를 의무화하고 있으며, 이에 따라 방음벽, 방음터널 등 다 양한 방음시설이 소음저감 대책으로서 현장의 여건에 따라 사용되고 있다. 최근, 배수성 아스팔트 포장이 노면에서의 흡음에 따른 타 이어-노면 간의 마찰소음 저감 효과를 바탕으로 손쉽게 적용할 수 있는 방음대책의 하나로 활용되고 있다. 하지만, 저소음 아스팔트 포장이 일반 아스팔트 포장에 비해 환경소음을 저감시킬 수 있는지 정량적으로 평가하는 것이 매우 어려운 상황이다. 최근 타이어-노 면 간의 마찰소음을 정량적으로 평가할 수 있는 CPX 측정방법이 KS I ISO 11819-2로 표준화되어 국토부의 ‘배수성 아스팔트 콘크리 트 포장 생산 및 시공지침’ 중 소음 측정방법에도 인용되어 있다. 하지만, CPX 방법은 정속 주행시 환경의 영향을 통제한 상태에서 근접 소음만을 측정하기 때문에, 포장 종류나 경년변화에 따른 상대적인 차이를 정량화하는 것은 유리하지만, 환경기준에 따른 소음저 감도를 직접적으로 비교할 수 없는 단점이 있다. 이에 따라, 본 연구에서는 CPX 측정방법으로 도출한 포장구간별 소음저감량과 환경 소음 평가의 기준이 되는 갓길에서 측정한 등가소음간의 상관관계 분석을 통해, 환경소음 관리 및 도로소음 평가를 위한 CPX 측정결 과의 활용방안에 대해 고찰하였다.

Electric-propulsion systems for ships, also known as electric propulsion devices, represent the current direction of development for maritime power. Issues concerning the environment and fuel economy have compelled the maritime transport sector to seek solutions that reduce emissions and improve fuel efficiency. In this process, power electronics technology plays a significant role in the propulsion systems of ships. Selecting an efficient battery system is of great importance for enhancing the cruising range of yachts and minimizing environmental impact. The battery model is crucial for revealing the working principles of batteries, and it is extremely critical for the application and development of battery technology. The Battery Management System (BMS) serves a crucial regulatory function, optimizing both the safety and performance of battery cells. Central to its operation is the precise estimation of the battery's State of Charge (SOC), a process dependent on an exacting battery model. This system not only enhances longevity and reliability but also ensures that energy storage solutions meet high standards of efficacy. This study focused on testing the impedance characteristics of lithium-sulfur batteries (LSB) at various SOC points and establishing first- and second-order RC equivalent circuit models. The model parameters were identified through experimental data. Subsequently, a simulation platform was constructed using MATLAB/Simulink to simulate the behavior of LSB under a constant current discharge condition. The simulation results showed that the second-order RC model had significantly lower errors than the first-order model, demonstrating higher accuracy. These achievements can provide technical support for the research of energy storage systems in the green aviation and maritime industries.

In Korea, five major ports have been designated as sulfur oxide emission control areas to reduce air pollutant emissions, in accordance with Article 10 of the “Special Act on Port Air Quality” and Article 32 of the “Ship Pollution Prevention Regulations”. As regulations against vesseloriginated air pollutants (such as PM, CO2, NOx, and SOx) have been strengthened, the Ministry of Oceans and Fisheries(MOF) enacted rules that newly built public ships should adopt eco-friendly propulsion systems. However, particularly in diesel–electric hybrid propulsion systems,the demand for precise control schemes continues to grow as the fuel saving rate significantly varies depending on the control strategy applied. The conventional Power Take In–Power Take Off(PTI–PTO) mode control adopts a rule-based strategy, but this strategy is applied only in the low-load range and PTI mode; thus, an additional method is required to determine the optimal fuel consumption point. The proposed control method is designed to optimize fuel consumption by applying the equivalent consumption minimization strategy(ECMS) to the PTI–PTO mode by considering the characteristics of the specific fuel oil consumption(SFOC) of the engine in a diesel–electric hybrid propulsion system. To apply this method, a specific fishing vessel model operating on the Korean coast was selected to simulate the load operation environment of the ship. In this study, a 10.2% reduction was achieved in the MATLAB/SimDrive and SimElectric simulation by comparing the fuel consumption and CO2 emissions of the ship to which the conventional rule-based strategy was applied and that to which the ECMS was applied.

The temperature of the spent fuel cladding is the basis for the evaluation of integrity. It is almost impossible to directly measure the temperature of spent nuclear fuel. Because spent nuclear fuel is dangerous. We are preparing a test to measure the cladding temperature with an equivalent fuel assembly by simulating the characteristics of spent nuclear fuel. PLUS7 was selected as the test target in consideration of the amount of generation, thermal water retention, residual moisture content, and manufacturability of domestic spent nuclear fuel. The nuclear fuel assembly is planned to be manufactured in two main ways. Except for the cladding tube that simulates decay heat, the structure will be manufactured by KEPCO Nuclear Fuel, and fuel rods and canisters will be manufactured by SUKEGAWA Electric in Japan. The same nuclear fuel assemblies as commercial skeleton will be applied. The temperature of the fuel cladding will be measured by attaching a thermocouple directly to the surface of the cladding tube. The canister is composed of a basket, a basket supporter, a heater and drain tube, a lead, and an observation window. The working fluid is water and helium, and the maximum pressure inside the canister is 1.1 MPa and the minimum pressure is 0.05 kPa. The maximum temperature of the surface of the cladding was designed to be 500°C, and the maximum temperature of the sealing to keep airtightness was designed to be 250°C. To satisfy this condition, we plan to evaluate the leak rate below 10−5 std.cm3·s−1, which is equivalent to helium tightness. The maximum heat of decay per fuel rod is 13 W, and one assembly is up to 3 kW. Production of the test equipment is expected to be completed in the first half of next year, and testing is scheduled to begin in the second half of next year. The test will evaluate all environments that the spent nuclear fuel may experience, such as dry normal conditions, abnormal conditions, wet conditions, and dry conditions. All data will be used for interpretation verification purposes.

A program was written that calculates the contact point and rolling radius difference by considering the lateral displacement of the wheelset with respect to the rail. The characteristics of the equivalent conicity were analyzed according to the distribution characteristics of wheelset lateral displacement using the calculated rolling radius difference. The standard deviation value representing the characteristics of the wheelset lateral movement should be appropriately applied considering the range of the lateral wheelset displacement. If a small standard deviation value is applied when the lateral displacement increases during actual driving condition, the equivalent conicity could be underestimated, which may cause a problem in determining a reliable stability of the railway vehicle.

When performing finite element analysis using materials with porosity the porosity shows different mechanical properties from the existing mechanical properties of the existing base materials. In this study the equivalent properties were calculated and verified by applying the representative volume element (RVE) method and assuming that the material with porosity is a 2D orthotropic material. In case of finite element analysis using porous material or composite material, it is inefficient to perform the analysis through material modeling. Based on the element volume and element stress values ​​derived using the finite element analysis program, the representative stress values ​​and elastic modulus matrix were calculated using Python. In addition, equivalent properties were derived using the calculated elastic modulus matrix. The pores were simulated by etching a thin plate specimen made of STS304 material in a certain pattern, and the elastic modulus and Poisson's ratio were measured through a UTM and compared with simulation results. It was confirmed that an error of 7.028% for elastic modulus and 10% for Poisson's ratio occurred, and through this, the validity of this simulation was verified.

The demand for materials with porosity is steadily increasing and the need for porous materials is increasing in fields such as chemical engineering and energy storage. In order to minimize trial and error, verifying design validity through finite element method at the design stage has the advantage to verify design validity with low cost. However there are limitations in finite element analysis using porous materials. In this study calculating the equivalent mechanical properties reflecting the porosity was carried out, and the first step was the isotropic elasticity in plane stress condition. The equivalent elastic modulus and the equivalent Poisson's ratio were derived through simulation. Assuming that the voids exist in a two-dimensional symmetrical shape and a constant distribution, the unit cell was defined and the equivalent mechanical properties were calculated. The specimen with same condition were measured through a universal test machine (UTM), the elastic modulus and Poisson's ratio were measured. The similarity between the value obtained through the simulation and the value measured through the experiment was under 5%, so the validity of this simulation was verified. With this result, FEM with porous materials will be used for design.

A corrugated steel plate wall (CSPW) system is advantageous to secure the strength and stiffness required for lateral force resistance because of its high out-of-plane stability. It can also stably dissipate large amounts of energy even after peak strength. In this paper, a preliminary study has been carried out to use the CSPW system in the seismic retrofit of existing reinforced concrete (RC) moment frame buildings. The seismic performance for an example building was evaluated, and then a step-by-step retrofit design procedure for the CSPW was proposed. An equivalent analytical model of the CSPW was also introduced for a practical analysis of the retrofitted building, and the strengthening effect was finally evaluated based on the results of nonlinear analysis.

In this study, the effect of carbon equivalent and cooling rate on microstructure and hardness of A516 steels for pressure vessel is investigated. Six kinds of specimens are fabricated by varying carbon equivalent and cooling rate, and their microstructures and hardness levels are analyzed. Specimens with low carbon equivalent consist of ferrite and pearlite. As the cooling rate increases, the size of pearlite decreases slightly. The specimens with high carbon equivalent and rapid cooling rates of 10 and 20 oC/s consist of not only ferrite and pearlite but also bainite structure, such as granular bainite, acicular ferrite, and bainite ferrite. As the cooling rate increases, the volume fractions of bainite structure increase and the effective grain size decreases. The effective grain sizes of granular bainite, acicular ferrite, and bainitic ferrite are ~20, ~5, and ~10 μm, respectively. In the specimens with bainite structure, the volume fractions of acicular ferrite and bainitic ferrite, with small effective grains, increase as cooling rate increases, and so the hardness increases significantly.

본 연구는 지역 클러스터 내에 존재하는 기술지식 교류 네트워크의 전반적인 구조적 특징을 파악하기 위해 사회네트워크 분석에 토대한 구조적 등위성 분석을 실증적으로 수행한다. 지금까지 기존 연구들은 구조적으로 등위적인 집단들 간에 성과차이가 존재하는 것으로 개념적으로 주장하였다. 그러나, 이에 대한 실증연구가 거의 없어 본 연구가 이를 보완하기 위해 수행되었다. 분석을 위해 구미국가산업단지 내에서 53개의 기술지식 교류 관련 협회 등을 조사하여 2550개 기업의 2-mode 네트워크 데이터를 활용하였다. 분석결과, 구조적 등위 집단들이 규정되고 중요한 기업들의 속성에 기초하여 네트워크 기존기업(established firms), 중개 기업(broker firms), 신생기업(emerging firms), 고립 기업(isolationist firms)으로 4개의 역할이 결정될 수 있었다. 또한, 블록 1에서 불록 4로 구분된 각각의 구조적 등위 집단들 즉, 역할들 간의 성과(매출액), 급진적 혁신성향, 기술혁신역량 차이에 대한 검증에서는 역할마다 검증결과가 차별적일 수 있음이 본 연구를 통해 제시되었다. 마지막으로 본 연구는 구조적으로 등위적인 집단들 간의 성과차이에 대한 연구를 발전시킬 필요성을 제안한다.

Among the 8,700 in-service bridges in national highway, the steel bridges cover the 1600 sites and make up approximately the 20 percentage of the total amounts. Due to recent rapid increase both in traffic volume and in frequency of overloaded vehicles, the need for re-evaluating the fatigue life of the steel bridges is increasing. However, the existing fatigue life assessment method are too complicate and difficult to apply to field directly. To improve such deficiency of the existing fatigue life assessment procedures, this study reviews the fatigue life assessment methods in Eurocode and then proposes an easier and simpler fatigue life assessment procedure that could evaluate the remaining fatigue life of the steel bridges using traffic data collected from a high-speed weigh-in-motion system installed in the national highway network. The Proposed fatigue life evaluation method is as follows; 1. Calculation of fatigue resistance 𝛾𝑀f and fatigue strength Δ𝜎𝑐 used in design, 2. Calculation of partial safety factor 𝛾𝐹f for equivalent stress range, 3. Calculation of stress range Δ𝜎𝐸2 using influence line, 4. Calculation of damage equivalent factor λ, 5. Review of Fatigue state and evaluation of fatigue life. The Proposed method can omit the existing complicated and repetitive calculation. Therefore, proposed method can estimate the fatigue damage and the theoretical fatigue life simply by comparing with the existing method.