• Journal of the Korean Society of Manufacturing Process Engineers
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• v.21 no.4
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• pp.1-13
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• 2022

Household refrigerator cabinets must undergo cyclic testing at -20 ℃ and 65 ℃ for quality control (QC) after their production is complete. These cabinets were assembled from different materials, including acrylonitrile butadiene styrene (ABS), polyurethane (PU) foam, and steel plates. However, different thermal expansion values could be observed owing to differences in the mechanical properties of the materials. In this study, a technique to predict delamination on a refrigerator wall caused by thermal deformation was developed. The mechanical properties of ABS and PU foams were tested, theload factors causing delamination were analyzed, delamination was observed using a high-speed camera, and comparison and verification in terms of stress and strain were performed using a finite element model (FEM). The results indicated that the delamination phenomenon of a refrigerator wall can be defined in two cases. A method for predicting and evaluating delamination was established and applied in an actual refrigerator. To determine the effect of temperature changes on the refrigerator, strain measurements were performed at the weak point and the stress was calculated. The results showed that the proposed FEM prediction technique can be used as a basis for virtual testing to replace future QC testing, thus saving time and cost.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.450-453
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• 2002

In radiotherapy treatment planning, it is critical to deliver the radiation dose to tumor and protect surrounding normal tissue. Recent developments in functional imaging and radiotherapy treatment technology have been raising chances to control tumor saving normal tissues. A brain phantom which could be used for image registration technique of CT-MR and CT-SPECT images using surface matching was developed. The brain phantom was specially designed to obtain imaging dataset of CT, MR, and SPECT. The phantom had an external frame with 4 N-shaped pipes filled with acryl rods, Pb rods for CT, MR, and SPECT imaging, respectively. 8 acrylic pipes were inserted into the empty space of the brain phantom to be imaged for geometric evaluation of the matching. For an optimization algorithm of image registration, we used Downhill simplex algorithm suggested as a fast surface matching algorithm. Accuracy of image fusion was assessed by the comparison between the center points of the section of N-shaped bars in the external frame and the inserted pipes of the phantom and minimized cost functions of the optimization algorithm. Technique with partially transparent, mixed images using color on gray was used for visual assessment of the image registration process. The errors of image registration of CT-MR and CT-SPECT were within 2mm and 4mm, respectively. Since these errors were considered within a reasonable margin from the phantom study, the phantom is expected to be used for conventional image registration between multimodal image datasets..

• Journal of Appropriate Technology
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• v.7 no.1
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• pp.59-71
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• 2021

Hybrid hydrothermal carbonization (Hybrid HTC) technology is a proprietary thermochemical process for two or more organic wastes.The reaction time is less than two hours with temperature range 180~250℃ and pressure range 20~40bar. Thanks to accumulation of the carbon of the waste during Hybrid HTC process, the energy value of the solid fuel increases significantly with comparatively low energy consumption. It has also a great volume reduction with odor removal effect so that it is evaluated as the best solid fuel conversion technology for various organic wastes. In this study of the hybrid hydrothermal carbonization, the effect on the calorific value and yield of Cambodian mango waste were evaluated according to changes in temperature and reaction time. Through the study, parameter optimization has been sought with improving energy efficiency of the whole plant. It is decomposed in the Hydro-Carbonation Technology to Generate Gas. At this time, it is possible to develop manufacturing and production technologies such as hydrogen (H₂) and methane (CH₄). Based on the results of the study, a pilot plant (2t/day) has been proposed for future commercialization purpose along cost analysis, mass balance and energy balance calculations.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.12
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• pp.863-870
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• 2012

The market trends of automatic meter reading associated with smart water meters were investigated. Also, recent developments and field applications of key technology for automatic meter reading associated with smart water meters were analyzed. Smart water meters have been manufactured mostly in United States and Europe and have been expanded their business to Asia. Integrated water management system combining with the additional functions such as real-time consumption metering, cost notification, water conservation, leak detection, water quality monitoring, and flow control have been operated in automatic meter reading. Both water quality and quantity data measured from smart water meters and sensors were transferred to data concentration units through neighborhood area network, and then were transferred to integrated server through wide area network. The data transfer methods were determined by comprehensively considering urban scale, density of smart water meters, power supply and network topologies. Common data collection methods such as fixed network to data concentation units, vehicles drive by, people walk by, and drone fly by have been applied. The automatic meter reading associated with smart water meters are spread throughout the world, and both water and energy savings result in saving the money and reducing the greenhouse gases emission.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.51-51
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• 2010

Recently just as in the automobile industry, shipbuilders also try to reduce material consumption and weight in order to keep operating costs as low as possible and improve the speed of production. Naturally industry is ever searching for welding techniques offering higher power, higher productivity and a better quality. Therefore it is important to have a details research based on the various welding process applied to steel and other materials, and to have the ability both to counsel interested companies and to evaluate the feasibility of implementation of this process. Submerged-arc welding (SAW) process is usually used about 20% of shipbuilding. Similar to gas metal arc welding(GMAW), SAW involves formation of an arc between a continuously-fed bare wire electrode and the work-piece. The process uses a flux to generate protective gases and slag, and to add alloying elements to the weld pool and a shielding gas is not required. Prior to welding, a thin layer of flux powder is placed on the work-piece surface. The arc moves along the joint line and as it does so, excess flux is recycled via a hopper. Remaining fused slag layers can be easily removed after welding. As the arc is completely covered by the flux layer, heat loss is extremely low. This produces a thermal efficiency as high as 60% (compared with 25% for manual metal arc). SAW process offers many advantages compared to conventional CO2 welding process. The main advantages of SAW are higher welding speed, facility of workers, less deformation and better than bead shape & strength of welded joint because there is no visible arc light, welding is spatter-free, fully-mechanized or automatic process, high travel speed, and depth of penetration and chemical composition of the deposited weld metal. However it is difficult to application of thin plate according to high heat input. So this paper has been focused on application of the field according to SAW process for thin plate in ship-structures. For this purpose, It has been decided to optimized welding condition by experiments, relationship between welding parameters and bead shapes, mechanical test such as tensile and bending. Also finite element(FE) based numerical comparison of thermal history and welding residual stress in A-grade 3.2 thickness steel of SAW been made in this study. From the result of this study, It makes substantial saving of time and manufacturing cost and raises the quality of product.

• Clean Technology
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• v.14 no.2
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• pp.129-135
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• 2008

Nylon membrane was used to separate ethanol-water by a pervaporation method. Experimental equations were derived to use the simulation of membrane-aided distillation using nylon. The increases in permeation pressure resulted in the decrease in selectivity and energy consumption. The energy cost to enrich ethanol from 94 wt% to 99.5 wt% was calculated to be 53.3 won/kg of ethanol with extractive distillation and 18.9 won/kg of ethanol with a pervaporation method. The saving energy by the pervaporation method is consumed by recycling the permeate residue into the distillation column in the membrane-aided distillation column. Therefore, membrane with the high selectivity to minimize the permeate residue recycle is required to effectively enrich ethanol in the membrane-aided distillation method.

• THE INTERNATIONAL COMMERCE & LAW REVIEW
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• v.46
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• pp.29-60
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• 2010

The incentive and reasons to publish FIDIC Conditions of Contract for Design, Build and Operate Projects(DBO Form) are manifold. It is partly a response to the increasing need for sophisticated project delivery methods in both the public and private sectors and the already widespread use of the FIDIC Yellow Book with operation and maintenance obligations and partly a response to the challenge to decrease maintenance cost to a minimum by means of a new procurement route. As a result, FIDIC has developed a new model form to meet this market place requirement. On the other hand, FIDIC did not simply adapt the Yellow Book but has developed a new form from it, whilst preserving the style of the already known FIDIC Forms and maintaining the wording where it was not necessary to change it for the purposes of a DBO Form. Moreover DBO Form fills up supposed gaps in other FIDIC Forms and ameliorates the claim management and dispute management framework. FIDIC DBO approach may be shortly summarized as follows. First, DBO Form provides for single project responsibility. Second, DBO Form has the clear objective of ensuring the use of a most reliable and efficient technology at the lowest life-cycle cost. Third, DBO Form is intended to operate as an effective quality increase in the design and construction of projects. Fourth, DBO Form is intended to provide significant benefits with regard to system integration and reduction of risks. Fifth, DBO Form accelerates and enhances completion schedule compliance. Sixth, DBO takes care of all three supporting pillars of sustainability(including economical, environmental and social elements). DBO Form is obviously a good starting point for negotiations and the preparation of calls for tenders, thus saving the parties time and money. However, existing cultural and legal differences, particular local conditions and the particular needs of some branches of the industry may require the form to be adapted according to the particular needs of a project. And Civil law practitioners are strongly recommended to verify carefully the underlying legal concepts and background of each clause of the General Conditions in order to avoid unnecessary and sometimes unnatural changes and amendments being made. Note that when preparing the Particular Conditions ensure that terminology is consistent and that existing inherent concepts should not be ignored.

• Resources Recycling
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• v.9 no.1
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• pp.36-43
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• 2000

This study was carried out for treatment and reuse of inorganic sludge from Fenton process at B dyeing wastewater treatment plant. The parameters for pilot-scale treatment system were derived from the results of this study. It was found that $COD_{cl}$ of the treated effluent became lower than 100 mg/l approximately on the optimal reaction condition. 2nd sludge which was generated after redissolving sludge was analyzed, and it showed that reduction ratio of ash in 2nd sludge and total dry sludge weight in comparison with current sludge were 85% and 65%. Also Fe salt in sludge was redissolved about 90~95% of initial Fe by weight. It was estimated almost ￦350,000,000 for sludge reuse process. It was estimated saving of about ￦1,300,000 per day (￦420,000,000 per year) in operating cost based on 30,000 $m^3$/d treatment, which these were about ￦430,000 per day in chemical, ￦1,100,000 per day in sludge transportation and ￦200,000 per day in equipment maintenance. Payback period with interest charge for investment cost was estimated about 10.5 months. Also, net present value (NPV) was ￦792,000,000 and internal rat of return (IRR) was about 110%.

• Clean Technology
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• v.16 no.3
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• pp.213-219
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• 2010

Vortex tube is the device that can separate small particles from the compressed gas, as well as compressed gas into hot and cold gas. Due to energy and particle separation ability, a vortex tube can be used as the main component of the $CO_2$ absorption device. In this study, experimental approach has been performed to analyze the energy separation characteristics of the vortex tube. To obtain the preliminary design data, energy separation characteristics of the vortex tube has been tested for orifice diameter, nozzle area ratio, and tube length. As a result, the orifice diameter is the major factor of the vortex tube design. The nozzle area ratio and tube length have a minor effect on the energy separation performance. For Dc=0.6D, AR=0.14~0.16, and L=16D, maximum energy separation has been occurred. The result from this study can be used as the basic design data of the $100Nm^3$/hr class vortex tube applied to the $CO_2$ absorption device. Compared with the $CO_2$ absorption process containing an absorption tower, the process with a vortex tube is expected to have a huge advantage of saving the installation space and the operating cost.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.4
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• pp.95-103
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• 2012

Precast concrete method is known to have advantages of minimizing works in the construction, controlling concrete quality easily and saving construction period due to only fabrication work in the construction field, but it needs to apply steam curing to accelerate early concrete strength. In the meanwhile, the oil cost for steam curing has been continuously increased because of political instability in the middle East and international economic shaky. Thus, this study addresses the development of precast/ prestressed concrete which has over 14MPa at 1 day age and specified concrete strength of 40MPa at low temperature, not applying steam curing. Tests were carried out in terms of material characteristics in fresh concrete and compressive strength using 3 types of cement such as Type I, Type III and rapid hardening compound cement. As results of tests, it is found that cements for rapid hardening had disadvantages with respect to slump, slump loss, and air content, but showed higher compressive strength than specified one, especially the highest value when using rapid hardening compound.