• Geomechanics and Engineering
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• v.34 no.4
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• pp.409-424
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• 2023

Response of the pipeline crossing fault is considered as the large strain problem. Proper estimation of the pipeline response plays important role in mitigation studies. In this study, an advanced continuum modeling including material non-linearity in large strain deformations, hardening/softening soil behavior and soil-pipeline interaction is applied. Through the application of a fully nonlinear analysis based on an explicit finite difference method, the mechanics of the pipeline behavior and its interaction with soil under large strains is presented in more detail. To make the results useful in oil and gas engineering works, a continuous pipeline of two steel grades buried in two clayey soil types with four different crossing angles of 30°, 45°, 70° and 90° with respect to the pipeline axis have been considered. The results are presented as the fault movement corresponding to different damage limit states. It was seen that the maximum affected pipeline length is about 20 meters for the studied conditions. Also, the affected length around the fault cutting plane is asymmetric with about 35% and 65% at the fault moving and stationary block, respectively. Local buckling is the dominant damage state for greater crossing angle of 90° with the fault displacement varying from 0.4 m to 0.55 m. While the tensile strain limit is the main damage state at the crossing angles of 70° and 45°, the cross-sectional flattening limit becomes the main damage state at the smaller 30° crossing angles. Compared to the stiff clayey soil, the fault movement resulting 3% tensile strain limit reach up to 40% in soft clayey soil. Also, it was seen that the effect of the pipeline internal pressure reaches up to about 40% compared to non-pressurized condition for some cases.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.3
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• pp.23-32
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• 1982

This study was conducted to evaluate the temperature effects on the nightsoil, anaerobic digestion, whether it could be operated with a higher organic loading rate at a higher temperature during summer months, or with a lower organic loading rate at a lower temperature during winter months. A laboratory completely mixed digester was continuously operated at 11 different temperatures from $18.5^{\circ}$ to $60^{\circ}C$ with 30 days of HRT. The study results indicated that the best efficiency occurred at a temperature range of $35^{\circ}$ to $40^{\circ}C$, at which BOD and VS removal efficiencies were respectively 71 and 53 percent, and gas production rate was $0.6m^3/kg$ VS fed or $16m^3/m^3$ fed. BOD removal efficiency would be increased to 78 percent if the digester effluent settled for 24 hours. Since the digester efficiency decreased beyond this temperature range, this suggested the digester need not to operate a higher temperature even during the summer months. The laboratory results were in good agreement with those of the existing digester operated at a temperature range of $32^{\circ}$ to $40^{\circ}C$. Application of septage or cow manure to the digester with nights oil at a rate of 1 to 1 did not greatly affect the digester performances. In addition, the digester effluent could be treated aerobically without any dillution water. BOD and SS removal efficiencies were greater than 90 percent in this case.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.6
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• pp.449-469
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• 2011

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigerating Engineering during 2010. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) Research trends of thermal and fluid engineering have been surveyed as groups of general thermal and fluid flow, fluid machinery, and new and renewable energy. Various topics were presented in the field of general thermal and fluid flow. Research issues mainly focused on the thermal reliability of axial fan and compressor in the field of fluid machinery. Studies on the design of ground source heat pump systems and solar chemical reactors were executed in the field of new and renewable energy. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics and industrial heat exchangers. Researches on heat transfer characteristics included heat transfer in thermoelectric cooling/power generation systems, combined heat and power systems, carbon nano fluid with PVP, channel filled with metal foam and smoke ventilation in a rescue station of a railroad tunnel. Also the studies on flow boiling of R123/oil mixture in a plain tube bundle and R410A charge amount in an air cooled mini-channel condenser were reported. In the area of industrial heat exchangers, researches on plate heat exchanger, shell and tube heat exchanger, enthalpy exchanger, micro channel PCHE were performed. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics and industrial heat exchangers. Researches on heat transfer characteristics included heat transfer in thermoelectric cooling/power generation systems, combined heat and power systems, carbon nano fluid with PVP, channel filled with metal foam and smoke ventilation in a rescue station of a railroad tunnel. Also the studies on flow boiling of R123/oil mixture in a plain tube bundle and R410A charge amount in an air cooled mini-channel condenser were reported. In the area of industrial heat exchangers, researches on plate heat exchanger, shell and tube heat exchanger, enthalpy exchanger, micro channel PCHE were performed. (3) Refrigeration systems with alternative refrigerants such as hydrocarbons, mixed refrigerants, and CO2 were studied. Performance improvement of refrigeration systems are tried applying various ideas of refrigerant subcooling, dual evaporator with hot gas bypass control and feedforward control. The hybrid solar systems combining the solar collection devices with absorption chillers or compression heat pumps are simulated and studied experimentally as well to improve the understanding and the feasibility for actual applications. (4) Research trend in the field of mechanical building facilities has been found to be mainly focused on field applications rather than performance improvements. Various studies on heating and cooling systems, HVAC facilities, indoor air environments and energy resources were carried to improve the maintenance and management of building service equipments. In the field of heating and cooling systems, papers on a transformer cooling system, a combined heat and power, a slab thermal storage and a heat pump were reported. In the field of HVAC facilities, papers on a cooling load, an ondol and a drying were presented. Also, studies on HVAC systems using unutilized indoor air environments and energy resources such as air curtains, bioviolence, cleanrooms, ventilation, district heating, landfill gas were studied. (5) In the field of architectural environment and energy, studies of various purposes were conducted such as indoor environment, building energy, renewable energy and green building. In particular, renewable energy and building energy-related researches have mainly been studied reflecting the global interest. In addition, many researches which related the domestic green building certification of school building were performed to improve the indoor environment of school.

• Tunnel and Underground Space
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• v.24 no.6
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• pp.440-448
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• 2014

Hydraulic fracturing technique has been applied in various fields in order to improve the recovery of energy resources such as gas, oil and geothermal energy and research about finding out hydraulic fracturing mechanism and application has been steadily proceeded. In this study, for effective hydraulic fracturing, a scale modeling was progressed to simulate similarly with the actual site. In order to analyze the development aspect of surface crack initiation pressure during hydraulic fracturing followed by different conditions, the number of guide holes hydraulic fracturing test was carried out by setting up a hydraulic fracturing test equipment. Also, through the result, we tried to derive reliable results by comparing and analyzing the value of numerical modeling which is obtained based on the physical properties and mechanical properties with 3DEC, a three-dimensional discrete element method program. As a result, it is considered possible to generate effective crack using the guide hole.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.6
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• pp.137-143
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• 2007

An object of this study is to understand the application characteristics in accordance with changes of EGR rate, applying BD20 reformed by ultrasonic energy irradiation to common-rail diesel engine. BD containing about 10% oxygen has attracted attention due to soaring crude oil prices and environmental pollution. This oxygen decreases soot by promoting combustion, but it also increases NOx. To make up for this problem, an EGR system is applied so that NOx might be decreased. In that case, engine power is lowered and exhaust gas is raised. However, the reformed fuel by ultrasonic energy irradiation is changed physically and chemically, promotes combustion, and thus solves such a problem. As the results of the experimemt, we could identify the optimum EGR rate by investigating the engine performance and the characteristics of exhaust materials in accordance with the EGR rate after ultrasonic energy irradiation to BD20 and applying it to common-rail diesel engine. The optimum EGR rate that can satisfy both engine performance and characteristics of exhaust materials was in the range of 15%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.19-27
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• 2020

On an offshore plant topside, various types of offshore facilities for processing energy resources, such as oil and gas, and equipment and outfitting for connecting these facilities are installed in a limited space. An offshore plant superstructure is composed of numerous supporting rack structures and reinforcements for securing and supporting offshore installations and the related equipment. This paper describes the development of design support software to support this superstructure design efficiently. The developed design support software, which was based on AVEVA Marine's PML(Programmable Macro Language), supports the parametric method for superstructure design. A method of batch 3D modeling from 2D drawings for supporting rack structure produced in the basic and detailed design was also developed using AutoLisp. In addition, through the application example of superstructure module design, the design support software introduced in this paper can be expected to reduce the design time by more than 90% compared to the use of only basic functions of AVEVA PDMS.

• Journal of Environmental Science International
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• v.13 no.4
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• pp.339-347
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• 2004

This paper asks the question: what choice of environmental policy instruments is efficient to reduce sulfur dioxide from stationary sources\ulcorner: In Korea, command and control has been a common way of controlling $SO_2-emissions.$ When compared to the non-incentive environmental policy instrument such as command and control, economic incentive environmental policy instrument has been the advantage of making polluter himself flexibly deals with in marginal abatement cost to develop environmental technology in the long view. Therefore, the application possibility of the incentive environmental policy instrument was studied in this research to realize the countermeasure for controlling of $SO_2-emissions.$ As a result, enforcement of the countermeasure such as flue gas desulfurizer by command and control would be suitable because power generation is performed by the public or for the public in source of air pollution and thus, economic principle is not applied to the polluter. In the source of industrial pollution, enforcement of fuel tax is found to be suitable for the countermeasure for the use of low sulfur oil in terms of the flexibility of demand for the price in the long tenn. For the permissible air pollution standards applicable to all air pollutant emitting facilities, enforcement of incentive environmental policy such as bubble, off-set, banking policy or tradeable emission penn its would be ideal in long terms according to the regional characteristics and the number and scale of air pollutant emitting facilities.

• Journal of the Korean Data and Information Science Society
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• v.22 no.3
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• pp.401-412
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• 2011

This study uses a vector error correction model to analyze the daily time series data of the spot price of EUA (European Union Allowance). As endogenous variables, five variables are considered for the analysis, including prices of crude oil, natural gas, electricity and coal in addition to carbon price. Data period is Phase 2 period (April 21, 2008 to March 31, 2010) to avoid Phase 1 period (2005-2007) where the EUA prices were distorted. Unit-root and cointegration test results reveal that all variables have a unit root and cointegration vectors exist, so a vector error correction model is adopted instead of a vector autoregressive model.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2004.05a
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• pp.341-346
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• 2004

In the present work, for various energy and electricity generating systems to be compared in view of integrated social impacts, nuclear, coal-fired, heavy oil-fired, and LNG, and hydroelectricity systems are considered as electricity generating options. The following assessment factors are selected: economic effect, health effect, environmental effect, and benefit at the national level. As a preliminary study, these factors are represented as power generation cost, estimated mortality, Carbon Dioxide gas emission, and fuel supply stability, respectively. For integrated representation of a multi-criteria decision-making (MCDM) problem, radar charts are introduced to facilitate a comparative recognition of estimates. In the near future, based on the estimates, a MCDM methodology for both qualitative and quantitative comparison will be developed.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.34-41
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• 2018

A flange joint is a pipe connection used to prevent the leakage of high-pressure fluids by inserting a gasket and tightening the bolts. Among several kinds of gaskets available, metal ring type joint gaskets are most widely used in conditions that require high-temperature and high-pressure fluid flow, such as oil pipelines, gas pipes, pumps, valve joints, etc. The purpose of this study is to investigate the contact pressure and stress characteristics closely related to the sealing performance of Class 900 flange joints used in high temperature and high pressure environments. The dimensions of flange joints with five different nominal pipe sizes were determined with reference to those specified in ASME 16.5. The metal ring gaskets inserted in the joints were octagonal and oval gaskets. The bolt tensile forces calculated from the tightening torques were input as the bolt pretension loads in order to determine the contact pressure and stress levels after fastening. Loading was composed of three steps, including the fastening step, and different amounts of applied pressures were used in each analysis to investigate the effect of fluid pressure on the contact force of the joints. A general-purpose software, ANSYS 17.2, was used for the analysis.