• Journal of the Society of Naval Architects of Korea
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• v.32 no.3
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• pp.19-28
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• 1995

This paper presents hull form design details and performance characteristics of the SWATH ship 'SEON JIN' built as an underwater test support ship. The hull form is developed systematically varing sets of 11 form parameters which define a unique hull under waterline. Using this geometry variation scheme we have generated a number of alternatives and selected the final hull which fulfills the design objectives and matches the design constraints. After selecting the final hull form we have investigated performances thoroughly through model tests, and confirmed through sea trials that the performance goals be achieved.

• Korean journal of food and cookery science
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• v.25 no.3
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• pp.337-344
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• 2009

The principal objective of this study was to determine the optimal mixing conditions of three different amounts of small black soybeans, sugar, and plain yogurt, for the preparation of a small black soybean smoothie. The experimental design utilized herein was based on the Central composite design methodology of response surface, which included 16 experimental points, including 2 replicates for the small black soybeans, sugar, and plain yogurt. The physiochemical and sensory properties of the test were measured, and these values were applied to the mathematical models. A canonical form and perturbation plot showed the influence of each ingredient on the mixed final product. The L value and a value decreased with increasing quantities of small black soybeans, but the b values increased with greater additions of small black soybeans. Sweetness increased with increasing amount of added sugar. The results of sensory evaluation showed very significant values for color (p<0.01), taste (p<0.05) and overall quality (p<0.05) in the predicted model. As a result, the optimum formulations by numerical and graphical methods were calculated as follows: small black soybean 79.46 g, plain yogurt 275.07 g, sugar 21.20 g.

• Journal of The Korean Astronomical Society
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• v.41 no.5
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• pp.109-119
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• 2008

We present an optical-infrared photometric study of galaxies in six nearby clusters of galaxies at $z=0.041{\sim}0.098$ (A1436, A1773, A1809, A2048, A2142, and A2152). Using BV I photometry obtained at the Bohyunsan Optical Astronomical observatory and $JHK_S$ photometry extracted from the 2-Micron All-Sky Survey catalog, we investigate the colors of galaxies in the clusters. Using the (B - V) versus ($I\;-\;K_S$) color-color diagrams in comparison with the simple stellar population model, we estimate the ages and metallicities of bright early-type member galaxies. Early-type galaxies in each cluster show the color-magnitude relation. Ages and metallicities of early-type members show little dependence on their velocity dispersions. Mean ages of early-types in the clusters range from 3 Gyr to 20 Gyr, showing a large dispersion, and mean metallicities range from Z = 0.03 to 0.05 above the solar value, showing a negligible dispersion.

• Carbon letters
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• v.15 no.2
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• pp.105-112
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• 2014

Wastewater from textile industries is a major cause of water pollution in most developing countries. In order to address the issues of water pollution and high cost for treatment processes, the use of an inexpensive and environmentally benign adsorbents has been studied. The objective was to find a better alternative to the conventional methods. Lemon grass waste (ash) collected from a lemon grass stream distillation subunit in Bhutan was tested for dye removal from aqueous solutions. The study investigated the removal of methylene blue using the following operational parameters: initial concentration (100-600 mg/L), contact time, adsorbent dose (0.1-0.55 gm/100 mL), and pH (3-10). It was found that the percentage removal of dye increased with a decrease of the initial concentration and increased contact time and dose of adsorbent. The basic pH solution of dye showed better adsorption capacity as compared to the acidic dye solution. Langmuir and Freundlich adsorption isotherms were fitted to the data well. Data fitted better to Lagergren pseudo 2nd order kinetics than a 1st order kinetic model. Surface morphology was also examined via scanning electron microscopy. An elemental analysis was also carried out and the chemical composition and functional groups were analyzed using energy dispersive X-ray spectroscopy and Fourier transform infrared spectroscopy techniques, respectively. The obtained results indicate that lemon grass ash could be employed as a low cost alternative to commercial activated carbon in wastewater treatment for the removal of dyes.

• Journal of computational fluids engineering
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• v.14 no.3
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• pp.56-62
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• 2009

In this study, the heat transfer and flow field of a condenser used for a Kim-chi refrigerator is analysed with numerical method. Main objective is to present the basic data for designing a new condenser model with improvement of heat transfer performance. For CFD analysis, a commercial code, STAR CCM+ was used. The water was used for the inner working fluid and the air was used for the outer fluid. The condenser type used in this study is a flat plate fin-and-tube heat exchanger. As analysis parameters, the effect of condenser geometry and air velocity was investigated. For validation of the numerical calculations, the results were compared with the experimental ones. The heat transfer rates for both results were consistent with each other by maximum 5 % error. Based on this comparison, the numerical analysis was done with some modifications. As a result, it has been observed that there is a suitable fin pitch with which heat transfer performance of condenser is maximized.

• Journal of the Korean Society of Costume
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• v.54 no.4
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• pp.129-144
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• 2004

The modems who lives complicated society, the silence which the Orient thought asserts leads and to get comfortable. It is becoming, the like this social atmosphere will in the interest regarding a manual example and the Orient material, the use of the embroidery textile goods is increasing specially. The purpose of this article is to suggest a model for development of machine embroidery fabric material and highly value added apparel industries. The multi-headed embroidery machine where the application scope is wide from the dissertation, we are requested' NaNa company'. The multiheaded embroidery machine uses TAJIMA TMFD-G620 and SUNSTAR SWF-／B-WD(X) 620-100 the embroidery textile uses the silk, the cotton and the synthesis fertile goods etc 24 type, the embroidery thread Maraton thread(viscose rayon 100％) with used the cord. The 8 Korean motives are made on 23 fabrics, 6 of which are full-sized manufactured one-pieces and the other 17 of which are produced to home interior goods such as curtains or fashion accessories like handbags as simulations. Among the products, the pattern-4-1 and the pattern-4-2 are contracted with local fashion industry, and the pattern-1-1～3 are dealing with other companies in Japan. The computerized machine-embroidering and simulation producing of fashion items are available to reduce the cost in making samples and transfer the old labor ＆ toil-centered industry into the new technique ＆ knowledge centered one.

• Journal of Communications and Networks
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• v.6 no.3
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• pp.258-268
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• 2004

We demonstrate rotationally invariant space-time (ST) trellis codes with a 4-D rectangular signal constellation for data transmission over fading channels using two transmit antennas. The rotational invariance is a good property to have that may alleviate the task of the carrier phase tracking circuit in the receiver. The transmitted data stream is segmented into eight bit blocks and quadrature amplitude modulated using a 256 point 4-D signal constellation whose 2-D constituent constellation is a 16 point square constellation doubly partitioned. The 4-D signal constellation is simply the Cartesian product of the 2-D signal constellation with it-self and has 32 subsets. The partition is performed on one side into four subsets A, B, C, and D with increased minimum-squared Euclidian distance, and on the other side into four rings, where each ring includes four points of equal energy. We propose both linear and nonlinear ST trellis codes and perform simulations using an appropriate multiple-input multiple-output (MIMO) channel model. The 4-D ST codes constructed here demonstrate about the same frame error rate (FER) performance as their 2-D counterparts, having however the added value of rotational invariance.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.3
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• pp.7-12
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• 2007

This paper presents an energy saving hydrostatic pressure exchanger for sea water desalination equipment. In a reverse osmosis(RO) system for desalinating sea water, more than 70 percent of the supplied sea water, brines which were impassable through RO membrane are bypassed, resulting in high energy losses. In this paper, a hydrostatic pressure exchanger consisting of an embedded water hydraulic piston motor and a water hydraulic piston pump was proposed and investigated in order to recover the energy of the bypassed brines. The pressurized brines are supplied to the embedded water hydraulic piston motor as power sources and the water hydraulic piston pump is driven by the output torque of the embedded water hydraulic piston motor as well as electric motor. Consequently, the energy of the bypassed brines can be recovered. To examine the electric energy saving characteristics of the hydrostatic pressure exchanger, a simulation model was constructed using commercial software and experiments were conducted. Through the results of simulation and experiment, the feasibility of the electric energy saving effect of the proposed hydrostatic pressure exchanger was investigated.

• Environmental Engineering Research
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• v.25 no.4
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• pp.605-613
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• 2020

This study is to investigate the possibility of using activated carbon prepared from Iraqi date-pits (ADP) which are produced from palm trees (Phoenix dactylifera L.) as low-cost reactive material in the permeable reactive barrier (PRB) for treating lead (Pb⁺²) from the contaminated groundwater, and then compare the results experimentally with other common reactive materials such as commercial activated carbon (CAC), zeolite pellets (ZP). Factors influencing sorption such as contact time, initial pH of the solution, sorbent dosage, agitation speed, and initial lead concentration has been studied. Two isotherm models were used for the description of sorption data (Langmuir and Freundlich). The maximum lead sorption capacities were measured for ADP, CAC, and ZP and were found to be 24.5, 12.125, and 4.45 mg/g, respectively. The kinetic data were analyzed using various kinetic models particularly pseudo-first-order, pseudo-second-order, and intraparticle diffusion. COMSOL Multiphysics 3.5a depend on finite element procedure was applied to formulate transmit of lead (Pb⁺²) in the two-dimensional numerical (2D) model under an equilibrium condition. The numerical solution shows that the contaminant plume is hindered by PRB.

• Journal of Power System Engineering
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• v.9 no.4
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• pp.162-167
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• 2005

The purpose of this paper is to improve the hysteresis characteristics of a stack type piezoelectric actuator using system identification and tracking control. Recently, several printing methods that are cost less and faster than previous semiconductor processes have been developed for the production of electric paper and RFID(Radio Frequency IDentification). The system proposed in this study prints by spraying the molten metal. And this system consist of a nozzle, heating furnace, operating actuator and an XYZ 3-axis stage. As an operating system, the piezoelectric(PZT) actuator is a very useful tool for position control of the metal printing system. However, the PZT actuator has a hysteresis nonlinearity due to the ferroelectric characteristics of the PZT element. This hysteresis causes problem position control characteristics in the system and deteriorates the performance of the system. In this study, an investigation was conducted to improve the hysteresis characteristics of the PZT actuator that has an output displacement for the input voltage. In order to reduce the hysteresis nonlinearity of the PZT actuator, this proposed a inverse hysteresis model and a mathematic modeling method that can express the geometric relationship between voltage and displacement. In addition, system identification and PID control methods were examined. Also, it was confirmed that the proposed control strategy gives good tracking performance.