• The Korean Journal of Ceramics
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• v.7 no.2
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• pp.80-84
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• 2001

The anisotropic CdS platelets were synthesized in the lamellar bilayer phase region of the octylamine-water binary system. The influence of the synthesis conditions of the system components on morphology and size of the platelets was examined. Atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM) studies have shown thickness and face size of the synthesized particles. Platelets with face sizes ranging from 50 to 250 nm and thickness from 10 to 30 nm have been synthesized at room temperature. In addition, HRTEM micrographs show that the synthesized platelets are poly crystal.

• Korean Journal of Hydrosciences
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• v.2
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• pp.99-113
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• 1991

Integrated irrigation management system (IIMS) that is incorporated with a microcomputer-based decision support system (DSS) has been developed and applied to paddy rice irrigation systems management. The system hardwares consist of field data acquisition units, data transmission units, central data processing units, and printing and displaying units. Ridld data to be collected include incremental rainfall, streamflow and reservoir water levels, and water levels at several irrigation canal sections within an irrigation sidtricts. The softwares are to process field data, real-time forecasting, irrigation control data, and decision variables from data-base and simulation model subsystems. And the user-interface subsystems are incorporated to present the water system operators and managers the results from data and model sugsystems. User-friendly menu with animated graphic modules are adopted to help understand irrigation controls for the district. This paper issues the overal descriptions of DSS as applied to Anjuk irrigation district. The details of major model components for the irrigation controls are presented along with real-time data collection systems. The potentials of DSS have been appraised very practical and promising for better irrigation system operation and management.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.746-757
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• 2021

To investigate the mechanism of friction-induced vibration and noise of ship water lubricated stern bearings, a two-degree-of-freedom (2-DOF) nonlinear self-excited vibration model is established. The novelty of this work lies in the detailed analysis of influence of different parameters on the stability and nonlinear vibration characteristics of the system, which provides a theoretical basis for the various friction vibration and noise phenomenon and has a very important directive meaning for low noise design of water lubricated stern bearings. The results reveal that the change of any parameter, such as rotating speed of shaft, contact pressure, friction coefficient, system damping and stiffness, has an important influence on the stability and nonlinear response of the system. The vibration amplitudes of the system increase as (a) rotating speed of shaft, contact pressure, and the ratio of static friction coefficient to dynamic friction coefficient increase and (b) the transmission damping between motor and shaft decreases. The frequency spectrum of the system is modulated by the first mode natural frequency, which is continuous multi-harmonics of the first mode natural frequency. The response of the system presents a quasi-periodic motion.

• Fashion & Textile Research Journal
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• v.16 no.1
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• pp.153-159
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• 2014

This study evaluates the changes of the subjective hand, preference, comfort and mechanical properties of tricot based artificial suede made from sea-island type micro fibers according to raising condition. The subjective hand and the preference of raised suede for jacket were rated by the 20's and 30's women experts according to raising cycles. Comfort properties were evaluated by air permeability, water vapor transmission, and thermal transmission. Mechanical properties were measured by the KES-FB system. The subjective hand of artificial suede was categorized into three hand factors: smoothness, warmness and thickness. Smoothness, warmness and thickness perception increased with raising cycles which affected hand preference and luxuriousness perception. The thickness and wale density of suede increased with the number of raising. Suede became more compact and less pliable and less stretchable due to increased fabric thickness; in addition, the surface of suede became smoother and compressive since the surface evenness of suede improved with smaller fiber fineness and an increased amount of naps covered the base fabric. Furthermore, water vapor transmission decreased and thermal insulation increased. The best raising conditions for artificial suede was four cycles in which artificial suede was preferred without changes in physical properties.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.611-621
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• 1995

The objectives of this study are to find out and to analyze the heat transmission characteristics of the conventional and prefabricated Ondol systems. To compare the thermal characteristics of these Ondol, a real sized Ondol model is set in a chamber. Hot water whose temperature is varied from $45^{\circ}C$ to $60^{\circ}C$ with $5^{\circ}C$ interval is supplied to each Ondol system. At that time the temperature distribution of floor surface, the amount of supplied heat, the heat radiation aspect and the heat loss from the floor to the underground are measured and analyzed simultaneously. As a result, even if the supplied hot water temperature to the prefabricated Ondol panel is lower by about $5^{\circ}C$ than that of the conventional Ondol panel, the net radiant effect is same. Heat radiation efficiency of the prefabricated Ondol panel is over 5% better than that of the conventional Ondol panel. It takes 12 hours for the conventional Ondol and 45 minutes for the prefabricated Ondol, respectively to reach steady state.

• Korean Journal of Soil Science and Fertilizer
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• v.47 no.5
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• pp.313-318
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• 2014

The remote monitoring system of water salinity was assessed in Wando reclaimed land lake during a farming season in 2009. Increasing of water salinity in this lake used to bring about salt damage on rice plant occasionally. At the early stage of the rice growing period, rice growth was not damaged due to enough rainfall with more than 120 mm from the mid-May to the first ten days of June. Data collection using on-site water salinity measuring sensors every 2 hours and real-time transmission in system were carried out for the experiment. We compared the transmitted values from the sensor system with water sample values collected and analyzed by a local technical office. Salt concentrations measured by sensor in real-time monitoring system were available data. The regression equation between rainfall and water salinity was presented as (water salinity after rainfall) = $0.621{\times}$(water salinity before rainfall)${\times}exp(-0.0139{\times}rainfall)$, ($r^2=0.579$, p<0.01). It is suggested that the system is useful for stable farming in the area where farmer use water in reclaimed lakes as an irrigation source.

• Solar Energy
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• v.15 no.3
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• pp.59-73
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• 1995

The thermal analysis is accomplished with the route for the underground power transmission system which adopts the water pipe cooling with trough in tunnel. As a result, in case of a cooling system based on a refrigerator, the optimum condition for the flow rate of cooling water and the air velocity are calculated as the $2{\sim}3{\ell}/s/pipe$ and $1{\sim}2m/s/fan$, respectively. On the other hand, in case of cooling tower the optimum condition for them are calculated as the $2{\sim}3{\ell}/s/pipe$ and 6 m/s/fan, respectively. But the cooling system based on a cooling tower has the problem of enlarging the size of cooling fan and suppressing the labor of operator in tunnel. Therefore, to meet all the cooling conditions for a given cooling section, the cooling system based on a refrigerator is more acceptable.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.89-90
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• 2008

We present an implementation and it's real-sea test of an underwater acoustic communication system, which allows the system to reduce complexity and increase robustness in time variant underwater environments. For easy adaptation to complicated and time-varying environments of the ocean, all-digital transmitter and receiver systems were implemented. For frame synchronization the CAZAC sequence was used, and QPSK modulation/demodulation method with carrier frequency of 25kHz and a bandwidth of 5kHz were applied to generate 10kbps transmission rate including overhead. To improve transmission quality, we used several techniques and algorithms such as adaptive beamforming, adaptive equalizer, and convolution coding/Viterbi decoding. For the verification of the system performance, measurement of BER has been done in a very shallow water with depth of 20m at JangMok, Geoje. During the experiment, image data were successfully transmitted up to about 9.6km.

• 한국전산유체공학회:학술대회논문집
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• 2008.03b
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• pp.345-348
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• 2008

The computer-aided performance simulation can reduce periods for development of products and cut down on the cost comparing with former trial-and-error procedures. This study has developed a simulation program for a vehicle thermal management system integrating an engine cooling system and an air conditioning system considering interactions and arrangement of air side heat exchangers such as power steering oil cooler, air-cooled transmission oil cooler, condenser, and radiator. The program may be also used for the system performance analysis according to the configuration of the engine coolant side heat exchangers such as water-cooled transmission oil cooler, EGR cooler, and heater core. Experiments utilizing an environmental wind tunnel has been conducted to assess the performance of the system according to the arrangement of air side heat exchangers. Some modification of the coolant loop layout can enhance the heat core performance up to 7% according to the results of the simulations.

• Nuclear Engineering and Technology
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• v.55 no.9
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• pp.3126-3132
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• 2023

To meet the increasing heating needs of the China Fusion Experimental Tokamak Reactor (CFETR), the output power in each Lower Hybrid Current Drive (LHCD) transmission line should be increased from 250 kW to 500 kW. Therefore, a new high-power water load must be developed for the 4.6 GHz 500 kW LHCD system. This paper aims to report the most recent research progress of the water load: aluminum nitride (AlN) ceramic is used as the media material to isolate the water and vacuum, and the radio frequency (RF) simulation results show that the return loss of the water load is less than -25dB at 4.6 GHz over a wide temperature range. Under 500 kW continuous wave (CW) operation, the maximum temperatures of the ceramic and water are separately 67 ℃ and 62 ℃, resulting in thermal deformation of the ceramic of approximately 0.003 mm. Moreover, the AlN water load was tested on the 4.6 GHz 250 kW high-power test bench and found to work well with low reflected power.