Seismic qualification of equipment including piping is performed by using floor response spectra (FRS) or in-structure response spectra (ISRS) as the earthquake input at the base of the equipment. The amplitude of the FRS may be noticeably reduced when obtained from coupling analysis because of interaction between the primary structure and the equipment. This paper introduces a method using a modal synthesis approach to generate the FRS in a coupled primary-secondary system that can avoid numerical instabilities or inaccuracies. The FRS were generated by considering the dynamic interaction that can occur at the interface between the supporting structure and the equipment. This study performed a numerical example analysis using a typical nuclear structure to investigate the coupling effect when generating the FRS. The study results show that the coupling analysis dominantly reduces the FRS and yields rational results. The modal synthesis approach is very practical to implement because it requires information on only a small number of dynamic characteristics of the primary and the secondary systems such as frequencies, modal participation factors, and mode shape ordinates at the locations where the FRS needs to be generated.

Seismic responses due to the dynamic coupling between a primary structure and secondary system connected to a structure are analyzed in this study. The seismic responses are compared based on dynamic coupling criteria and according to the error level in the natural frequency, with the recent criteria being reliant on the error level in the spectral displacement response. The acceleration responses and relative displacement responses of a primary structure and a secondary system for a coupled model and two different decoupled models of two degrees-of-freedom system are calculated by means of the time integration method. Errors in seismic responses of the uncoupled models are reduced with the recent criteria. As the natural frequency of the secondary system increases, error in the natural frequency decreases, but seismic responses of uncoupled models can be underestimated compared to that of coupled model. Results in this paper can help determine dynamic coupling and predict uncoupled models’ response conservatism.

PURPOSES : In this study, a numerical clogging model that can be used to realistically visualize the movement of particles in cylindrical permeability test equipment was proposed based on the system coupling of computational fluid dynamics with the discrete element method and experimental permeability test results. This model can also be used to simulate the interaction of dust particles with bedding particles. METHODS: A 4-way system coupling method with multiphase volumes of the fluid model and porous media model was proposed. The proposed model needs to consider the influence of flow on the dust particles, interaction between the dust particles, and interaction between the dust particles and bedding layer particles. The permeability coefficient of the bedding layer in cylindrical permeability test equipment was not calculated by using the permeability test result, but was estimated by using the particle packing model and Ergun model. RESULTS : The numerical simulation demonstrated a good agreement with the experimental test results in terms of permeability and drain time. Additionally, the initial movement of particles due to the sudden drain hole opening was successfully captured by the numerical model. CONCLUSIONS : A 4-way coupling model was sufficient to simulate the water flow and particle movement in cylindrical permeability test equipment. However, additional tests and simulation are required to utilize the model for more realistic block pavement systems.

PURPOSES : In this study, a series of fundamental falling head permeability tests were conducted on a binary particle mix bedding to determine the minimum water level, bedding layer thickness, and amount of dust that can result in the stable permeability with high repeatability. The determined condition is used to develop a CFD-DEM coupled clogging model that can explain the movement of dust particles in flowing water of a block pavement system. METHODS: A binary particle mixture is utilized to experimentally simulate an ideal bedding layer of a block pavement system. To obtain a bedding layer with maximum packing degree, the well-known particle packing degree model, i.e., the modified Toufar model, was utilized. The permeability of the bedding layer for various water levels, bedding layer thicknesses, and amounts of dust was calculated. The permeability for a small water level drop was also plotted to evaluate the effect of dust on the bedding layer clogging. RESULTS: It was observed that a water level of 100 mm, bedding depth of 70 mm, and dust amount of 0.3 g result in a stable permeability condition with high repeatability. The relationship between the minimum dust amount and surface clogging of the bedding layer was suggested based on the evaluation of the volumetric calculation of the particle and void and the permeability change in the test. CONCLUSIONS: The test procedure to determine the minimum water level, bedding thickness, and dust amount was successfully proposed. The mechanism of clogging on the surface of the bedding layer was examined by relating the volumetric characteristics of dust to the clogging surface.

Coupling is commonly used as a mechanical fastener to connect the turbine housing and the bearing housing in a turbocharger assembly. The finite element analysis was used to predict the structural behaviors of the coupling system, which could be caused by the bolt clamping force in the assembly process and the thermal deformation during turbocharger operation. The back plate is used to prevent gas leakage from the turbine housing to the bearing housing while the fixed pin is inserted to set the reference position between the two parts. Thus, in order to predict the mechanical behaviors of the coupling system numerically, the temperature distributions were calculated by heat transfer analysis based on the rated speed of the diesel engine. As a result of analyzing the structural characteristics of the turbocharger, the contact pressure of the back plate was influenced by thermal deformations whereas the bending deformation of the fixed pin was affected by the thermal deformation and the pin position.

V-Coupling is commonly used as a mechanical fastener to connect the turbine housing and the bearing housing in a turbocharger assembly. The back plate between the turbine housing and bearing housing would be compressed by tightening torque of the coupling bolt in order to protect the gas leakage at a turbocharger’s operation. This paper presents the numerical and experimental method for the prediction of the mechanical behavior and sealing performance of the coupling system. The test was conducted to verify the finite element model by measuring the circumferential and axial direction strains of V-coupling under turbocharger’s assembly load. Finite element analysis was carried out to obtain the mechanical strains and contact pressures of the coupling. It can be seen that the analysis results are in good agreement with the measured strains from the coupling’s assembly load. And, the pressure distribution of the back plate also presented to identify the sealing performance of the turbocharger’s coupling system.

After studying the composition about the torsional shafting of main engine for fishing vessel with Power Take Off (PTO) System, the authors made a computer program using the transfer stiffness coefficient method (TSCM) for analyzing torsional vibration about the shafting with PTO system and nonlinear elastic coupling. The torsional shafting of main engine was separated by 3 types according to the connecting. The torsional shafting of main engine was separated by 3 types according to the connecting condition of main engine with propeller or the PTO system or both of them. In this paper, the change of natural frequencies and natural modes according to connecting condition of torsional shafting and nonlinear elastic coupling were analyzed. The accuracy of the TSCM was confirmed by comparing with the computational results of the Finite Element Method.

본 연구에서는 광대역 불규칙가진력을 받는 자기매계변수계의 모드상호작용을 고찰하였다. 고찰대상 모델은 매우 흔한 구조물의 형태인 내부공진을 갖는 자기매계변수 동흡진기이다. Gaussian closure 방법에 의하여 계의 불규칙 응답을 나타내는 동적 모멘트방정식은 1차 및 2차 모멘트로 구성된 자율 상미분방적식으로 줄여진다. 계의 평형해와 평형해의 안정성측면에서 계의 응답이 조사되었다. 참고문헌 [18]과 [20]에서 보고된 발견한 감쇠가 안정성을 축소하기도 한다라는 이 효과는 본 연구에서 발견할 수 없었다. 또한 확정적 비선형계에 존재하는 포화현상은 발견되지 않았다.

본 연구에서는 장어 통발어선 자동화 조업장치 개발의 첫 단계로서 통발을 모릿줄에 기계적으로 연결, 분리할 수 있는 장치인 집게식 통발연결장치 및 통발자동분리장치를 개발하여 해상성능실험을 실시하였다. 본 연구에서 얻어진 결과를 요약하면 다음과 같다. 1. 집게식 통발연결장치가 무른 꼬임 트와인 고다리 및 된 꼬임 트와인 고다리에 각각 연결되었을 때, 그 사이의 최대 인장하중은 각각 1379 N및 1,603 N 이었다. 2. 집게식 통발연결장치에 대한 해상성능시험 결과 성능이 양호함을 확인하였으며, 통발 회수율은 100% 이었다. 3. 통발자동분리장치에 대한 해상성능시험 결과 성능이 양호함을 확인하였으며, 통발 분리율은 100% 이었다.

This study investigated the use of a hydroxyl-radicals-generated microbubble/catalyst (MB/Cat) system for removing organic pollutants, nitrogen, and phosphorous from liquid fertilizer produced by livestock wastewater treatment. Use of the MB/Cat system aims to improve the quality of liquid fertilizer by removing pollutants originally found in the wastewater. In addition, a reduction effect has been reported for antibiotics classified as representative non-biodegradable matter. Samples of liquid fertilizer produced by an aerobic biological reactor for swine wastewater treatment were first analyzed for initial concentrations of pollutants and antibiotics. When the MB/Cat system was applied to the liquid fertilizer, TCOD, TOC, BOD5, and NH3-N, and PO4-P removal efficiencies were found to be approximately 52%, 51%, 30%, 21%, and 66%, respectively. Additionally, Amoxicillin hydrate was removed by 10%, and Chlortetracycline HCl and Florfenicol were not present at detectable levels These findings confirm that the MB/Cat system can be used with livestock wastewater treatment to improve liquid fertilizer quality and to process wastewater that is safe for agricultural re-use.

An experimental study was conducted to examine for the structural behavior of coupled steel plate shear wall (Coupled SPSW) system what is formed by connection the two steel plate shear walls (SPSW) with a coupling beam. The variable of this study was the length of coupling beam. The testing results were showed that the strength and stiffness of specimen with shorter coupling beam were improved than those of other specimen. However there is no difference of the yielding mechanism.

Since the late 20th century, the urbanization in Korea has been rapidly increasing, especially in major cities like Seoul, as a result of industrialization. One of the aspects of urbanization is coating the surfaces with impervious concrete or asphalt that water cannot penetrate. In addition, various urban, such as urban heat islands, which also have a great impact on the urban environment, occur within the cities. Therefore, the urban environment is gradually becoming hot and dry, and the need for more urban parks to compensate for these negative impacts is growing. Thus, several numerical studies have been conducted to assess these problems using coupled Numerical Weather Prediction (NWP) and Computational Fluid Dynamics (CFD). In this study, an experiment was conducted to determine the accuracy of the area of the input field using Weather Research and Forecasting (WRF) model, and applying the more accurate input field to a numerical simulation using ENVI-met, in order to investigate the effect of urban parks on the thermal comfort. The results showed that an input field with a larger area is more accurate than that with a smaller area, because the surrounding terrain and cities are considered in details in the experiment with the larger area. Subsequently, the more accurate input field was used in ENVI-met, and the results of this simulation showed that the presence of the urban park increased the thermal comfort and improved the humidity conditions.

Buildings nowadays are increasingly expected to need higher and more economic performance requirements. Energy consumption in buildings accounts for over 30% of total energy use. The Building Energy Management System (BEMS) and renewable energy (RE) technologies are considered as a potential measure to improve energy efficiency and reduce use of grid-power. It is, however, a challenge to utilise the intermittent energy supply of RE in building energy systems. This paper presents an experimental study on a RE-embedded BEMS. A control algorithm for the RE-embedded BEMS was designed to maximise the utilisation of RE and eventually to reduce electrical utility bill. The proposed system is tested at a laboratorial chamber with an air conditioner, fan and heater. The contribution of RE in building energy system is discussed to this end.

A system coupled the prognostic WRF mesoscale model and CALMET diagnostic model has been employed for predicting high-resolution wind field over complex coastal area. WRF has three nested grids down to 1km during two days from 24 August 2007 to 26 August 2007. CALMET simulation is performed using both initial meteorological field from WRF coarsest results and surface boundary condition that is Shuttle Radar Topography Mission (SRTM) 90m topography and Environmental Geographic Information System (EGIS) 30m landuse during same periods above. Four Automatic Weather System (AWS) and a Sonic Detection And Ranging (SODAR) are used to verify modeled wind fields. Horizontal wind fields in CM_100m is not only more complex but better simulated than WRF_1km results at Backwoon and Geumho in which there are shown stagnation, blocking effects and orographically driven winds. Being increased in horizontal grid spacing, CM_100m is well matched with vertically wind profile compared SODAR. This also mentions the importance of high-resolution surface boundary conditions when horizontal grid spacing is increased to produce detailed wind fields over complex terrain features.