• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.3 no.2
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• pp.87-96
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• 1991

A two-phase closed thermosyphon is applied to an ice storage system. The thermosyphon is used to freeze the water in a storage tank. The experiment has been performed to investigate the effects of the important parameters such as the quantity of the fluid filled with, the ratio of the length of the evaporator to the condenser, and the temperature and the mass flow rate of the brine. It is found that the higher thermal performance of the thermosyphon is obtained as the ratio of the length of the evaporator section to that of the condenser section is decreased and the temperature of the brine is lowered. The increase of the quantity of the working fluid also favors the performance of the system. The experimental data can be utilized for the basic design of ice storage systems with thermosyphons.

• Proceedings of the KSME Conference
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• 2001.06c
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• pp.451-456
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• 2001

Today, most of data storage devices use digital storage type. In this thesis, a new digital storage media called rainbow disk was introduced. It doesn't use 1-bit digital signal, but 2 or 4 bits digital signal using colors, so it can increase $2{\sim}4$ times more capacity than existing digital media in case of having the same spot size. It has made possible by means of technological advancement of devices and software. The photo quality paper was used for writing data by color inkjet or laser printing, and high resolution scanner was used for reading data. To extract data from image, the converting program was used. This paper shows the concept of rainbow disk as well as its performance and capacity. Axiomatic design was used for evaluating and developing the whole system.

• IE interfaces
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• v.17 no.spc
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• pp.52-61
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• 2004

During the past decades automated storage/retrieval (AS/R) systems have been dominantly implemented in most industrial fields due to their handling efficiency and high utilization of storage space. Such AS/R systems consist of several modules each of which contains two racks and a S/R machine. This paper proposes a design of the hybrid AS/R module which can be adopted without too much initial expenditure by most of small-and-medium sized companies. The hybrid module consists of an AS/R module on the upper floor and a traditional warehouse module on the lower floor. For the AS/R module, analytical expressions of the expected travel times for the S/R machine and the elevator per operation are derived. The expected travel times represent the performance of the module and thus can be used for its economic design.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.169-171
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• 2007

A breaking layer was introduced to conventional decal transfer method in membrane electrolyte assembly fabrication for high catalyst transfer ratio. In this study, the modified decal transfer method with high catalyst transfer ratio was introduced and its performance is studied. The structural features of electrodes made by decal method were investigated using scanning electron microscopy and current-voltage polarization measurement.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.5
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• pp.79-84
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• 2004

We evaluated the reduction performance of NOx storage catalyst and TWC for lean-burn natural gas engine by the model gas. The method of unsteady state reaction was used to compare with reduction performances of NOx storage catalyst and TWC. It was found that the effective parameter was rich spike duration, temperature of the model gas. In the presence of $CO_2$ and $H_2O$ in the reaction mixture was decreased the NOx reduction performance.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.2
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• pp.189-199
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• 2000

This paper investigates the thermodynamic performance of latent heat thermal energy storage system using two phase change materials(2-PCM system). The thermodynamic merit of using 2-PCM is clear in terms of exergetic efficiency, which is substantially higher than that of 1-PCM system. Optimum phase change temperature to maximize the exergetic efficiency exists for each case. The heat transfer area ratio of high temperature storage unit, X, becomes another important parameter for 2-PCM system if the phase change temperatures of given materials are different from those of optimum conditions. It is a good approximation for X$_{opt}$ to be 0.5 when optimum phase change temperatures are used. Otherwise X$_{opt}$ is determined differently as a function of given phase change temperatures.res.

• Journal of information and communication convergence engineering
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• v.2 no.1
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• pp.26-31
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• 2004

In the last few years, The Semantic Web has increased the interest in ontologies. Ontology is an essential component of the semantic web. Ontologies continue to change and evolve. We consider the management of versions in ontology. We study a set of changes based on domain changes, changes in conceptualization, metadata changes, and temporal dimension. In many cases, we want to be able to search in historical versions, query changes in versions, retrieve versions on the temporal dimension. In order to support an ontology query language that supports temporal operations, we consider temporal dimension includes transaction time and valid time. Ontology versioning brings about massive amount of versions to be stored and maintained. We present the storage policies that are storing all the versions, all the sequence of changed element, all the change sets, the aggregation of change sets periodically, and the aggregation of change sets using a criterion. We conduct a set of experiments to compare the performance of each storage policies. We present the experimental results for evaluating the performance of different storage policies from scheme 1 to scheme 5.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.4
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• pp.175-181
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• 2007

A computer model of a high efficiency refrigeration system equipped with heat storage for reverse cycle-hot gas defrost (the stored heat is used during defrost cycle of the system) is presented. The model was developed based on both theoretical and empirical equations for the compressor, evaporator, condenser and the heat storage equipment. Simulations of the prototype system were carried out to investigate refrigeration system performance under various operating conditions during refrigeration cycles. The simulations of the evaporator during defrost cycles at 30 and $40^{\circ}C$ hot gas refrigerant temperature were also performed which resulted on shorter defrost time but only slight increase in defrost efficiency. These information on energy efficiency and the defrost time required are important in order to avoid excessive parasitic load and temperature rise of the refrigerated room.

• Transactions of the Korean hydrogen and new energy society
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• v.30 no.1
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• pp.58-66
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• 2019

Static compound parabolic collectors (CPCs) have advantages such as ease for fabrication and lower cost compared with other concentrating collectors. In this study, thermal performance analysis of CPC employing heat storage tank was carried out. The clearness index and capacity of heat storage tank are taken as the main parameters for numerical simulation. The effects of the parameters on the hourly and daily system performances ncluding the useful energy, heat loss, and collector efficiency were numerically investigated. Results showed that the system has a potential for efficient recovery of solar thermal energy.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.11 no.2
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• pp.10-15
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• 1982

An experimental study on the storage tank which uses sensible heat of water is done. The influence of inlet flow rate (Re), the difference between initial temperature and inlet water temperature(Gr) and the location of inlet and outlet on the performance of storage tank is studied. Development of stratification is examined by measuring the transient temperatures of 36 points inside the tank. Measured values are transformed to the dimensionless parameters in order to calculate the temperature efficiency of storage tank. In the presence of combined natural and forced convection, the development of stratification becomes clearer and thus the efficiency becomes higher, as $Gr/Re^2$ increases.