• Journal of Internet of Things and Convergence
• /
• v.8 no.1
• /
• pp.23-29
• /
• 2022

The product to be developed in this study is a heat recovery device which generates steam or hot water at high temperature and high pressure by heating water using exhaust gas from diesel engine, gas engine, gas turbine, etc. as an exhaust gas boiler off heat boiler(EGB) type for ship and power generation. The steam vapor or the created warm water is used as the power source required for the steerage heating and hot water facility or the HFO heating of the ship, and the turbine drive. The principle of waste heat boilers serves to heat water as high temperature exhaust gas with heat pass through the tube of the boiler. The heated water is a structure that is sent to a cabin or turbine device in the form of steam. In this study, the objective of this study is to maximize the efficiency by increasing the heat transfer surface by replacing the tube which is the heat transfer part of EGB with the plate tube.

• The KSFM Journal of Fluid Machinery
• /
• v.19 no.4
• /
• pp.48-53
• /
• 2016

The centrifugal separator which uses gravity separation method for oil-water separation, rotating at high-speed, is one of the most commonly used device for controlling the amount of the oil in waste water collected in bilge. The IMO (International Maritime Organization) has set regulations, also known as MARPOL 73/78, for the prevention of marine pollution. In addition, DET NORSKE VERITAS (DNV) has set standards regarding the assignment of Environmental Class Notation, CLEAN or CLEAN DESIGN, of ships. One of the requirements for classification is that in addition to conforming to MARPOL 73/78, more stringent measures must be taken as well. One of these measures is to limit the oil concentration in bilge water to less than 5ppm. So in this study, an Oil-Water Separator (OWS) is used together with multiple separating plates as a filtration system to be used as an oil-water separation device. The OWS operates using centrifugal separation in which the mixture is separated by centrifugal forces. The main purpose of this paper is to present the OWS separation efficiency according to the rotation speed, mass-flow rate, the angle and the number of stacked layers of the laminated plate using Computational Fluid Dynamics (CFD). Improvements to the device will be investigated from these results.

• Journal of Advanced Marine Engineering and Technology
• /
• v.40 no.7
• /
• pp.563-568
• /
• 2016

In this study, experiments were conducted to evaluate the performance of a heat pump system. A heat pump system with an air as heat source is adapted as reference. The developed system uses a plate heat exchanger an evaporator to absorb heat from a stack of fuel cell driven electric vehicles. Hence, the system functions as a water source heat pump system. The results indicated that the; power consumption increased with the rotational speed of the compressor. A system performance($COP_h$) of 2.03 at an electronic expansion valve(EEV) openings of 25% and a compressor speed of 1200 rpm was observed in the reference system. However, at the same compressor speed, the $COP_h$ of the water source heat pump system corresponded to 9.42 at an EEV openings of 75%. It was found that the water source heat pump system exhibited the highest performance at a water temperature of $50^{\circ}C$.

• Composites Research
• /
• v.34 no.5
• /
• pp.269-276
• /
• 2021

PCM (Prepreg Compression Molding) process is a high-speed molding technology that can manufacture high-quality CFRP (Carbon Fiber Reinforced Plastic) parts. Compared to the autoclave process, it generates less waste and can significantly reduce cycle time, so various studies are being conducted in the aerospace and automobile industries. In this study, in order to improve the quality of the PCM process, a molding method was developed to increase the compression pressure of the press step by step according to the curing behavior of the prepreg. It was confirmed that this multi-stage compression molding technology is a good means to produce high-quality CFRP products and shorten cycle times. And, the laminated prepreg at room temperature was immediately put into the mold and preheated and molded at the same time, so that it could be molded without a separate preheating process. In addition, as a result of applying the same process conditions optimized for flat plate molding to three-dimensional shapes, a product similar to a flat plate in appearance could be made without the process of establishing process conditions.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2019.05a
• /
• pp.479-481
• /
• 2019

In recent years, training systems in various industrial fields have been made using virtual reality (VR) technology and widely used in education. Virtual reality based training system is safe, there is no waste of material, and there are many advantages to be able to practice anytime and anywhere. For example, virtual reality welding training simulation system is widely used for field worker because it can perform actual joining of steel plate in immersive environment. At this time, realistic representation of the steel plate joint is important to maximize the effectiveness of the training, but existing techniques have limited the natural expression of the effect. In this study, we propose a method of visualizing joint effect based on shader in order to construct welding training system. The results of this study can be applied to the welding training system to improve the weld training effect to provide the user with high-quality visualization.

• Journal of Korean Society on Water Environment
• /
• v.25 no.3
• /
• pp.363-369
• /
• 2009

We developed the Eco medium for Escherichia coli and total coliforms, which was modified by Violet Red Bile (VRB) medium, and derived the standard curve of exponential phase at $OD_{410}$ by using type strains such as E. coli ATCC11303, Enterobacter cloacae KCTC2361, Klebsiella pneumoniae KCTC2241, and Citrobacter freundii KCTC2359. Also, we used total 93 samples of spring and stream water to compare the detection ability of total coliforms between the method using Eco medium and such as most probable number (MPN), and plate count methods. As a result, the qualitative analysis of E. coli and total coliforms using Eco medium contained ortho-nitrophenyl-$\beta$-galactoside (ONPG) and 4-methylumbelliferyl-$\beta$-D-glucuronide (MUG) was same as those of Korean standard methods (Colilert kit). And the colony forming unit (CFU) detected in Eco medium was similar to those of result from MPN and plate count methods. Moreover, the agreement, sensitivity, and specificity of the developed kit was more than 97.5% in comparison with Colilert kit for 350 samples. Thus, the Eco medium can be used both qualitative and quantitative analysis of E. coli and total coliforms.

• Tunnel and Underground Space
• /
• v.8 no.3
• /
• pp.184-193
• /
• 1998

In order to dispose radioactive wastes safely, it is needed to understand the mechanical, thermal, fluid behavior of rockmass and physico-chemical interactions between rockmass and water. Also, the knowledge about mechanical and hydraulic properties of rocks is required to predict and to model many conditions of geological structure, underground in-situ stress, folding, hot water interaction, intrusion of magma, plate tectonics etc. This study is based on researches about rock mechanics issues associated with a waste disposal in deep rockmass. This paper includes the mechanical and hydraulic behavior of rocks in varying temperature conditions, thermo-hydro-mechanical coupling analysis in rock mass and deformation behavior of discontinuous rocks. The mechanical properties were measured with Interaken rock mechanics testing systems and hydraulic properties were measured with transient pulse permeability measuring systems. In all results, rock properties were sensitive to temperature variation.

• Journal of Energy Engineering
• /
• v.22 no.3
• /
• pp.307-311
• /
• 2013

Heating and hot water has accounted for 68% of Korea's household energy usage. Boiler makes up the bulk of the heating and hot water production. Hence a highly efficient boiler is needed in order to reduce energy consumption. A condensing boiler that recovers latent heat is known to be highly efficient. However, it is expensive and takes more space to necessitate research for improvement. In the present study, we investigated condensation heat transfer of a surface roughened by etching treatment. The etched plate showed 9.2% increase in heat transfer compared to original plate.

• The Korean Journal of Mycology
• /
• v.38 no.2
• /
• pp.120-124
• /
• 2010

This study was carried out to investigate interaction between mushroom mycelium and microorganisms in cotton waste media for the shelf cultivation of oyster mushroom. Two oyster mushroom farms was selected for this experiment. One was good mushroom farm (farmhouse I) and the other failed mushroom farm (farmhouse II). In farmhouse I, the inhibition microorganisms were higher toward the end of growth stage than the early stage, but the result of farmhouse II was opposite. Effects of the mycelium growth on plate culture showed same results on mushrooms as the earlier one. And the mycelium growth was influenced by secretory materials of microorganisms. Among of the isolates, Only few microorganism had inhibitory effects on either P. tolaasii or T. harzianum causing the disease of oyster mushrooms. But more microorganisms had inhibition effects on P. agarici.

• Journal of Nutrition and Health
• /
• v.31 no.9
• /
• pp.1498-1507
• /
• 1998

The purposes of this study were to : a) examine the current foodservice management practices of twenty-one seniors centers in charge of hoke-delivered meal programs, b) evaluate the attitudes of one hundred and ten recipients of meal service program, and c) provide feedback for the efficient and effective foodservice management for the elderly. Statistical data analysis was completed using the SAS package program for descriptive analysis, T-test, and ANOVA. The results of quantitative analysis indicated that the costs of meals, containers and special foods were mostly dependent on the support from local government(Seoul city). The centers where the volunteers were over seventy five p ercent of the workers were frtty-eight percent and sixty-seven percent of the subjects in food preparation and food delivery to the homebound clients, respectively. Meal preparation and food purchasing were mainly practiced by social welfare worker. Standardized recipes were not developed and meal preparation was controlled under the cook' and volunteers' experiences. The survey results of recipients who participated the home-delivered meals program showed that the mean of meal satisfaction score was rated over three point five in the five-point scale. There were significant differences between dependent variables(volunteer's kindness, plate waste, menu variety) and independent variables(sex, receiving periods and family type of the subjects). (Korean J Nutrition 31(9) : 1498-1507, 1998)