• Korean Journal of Mathematics
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• v.13 no.2
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• pp.183-191
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• 2005

In this paper we find the Laurent series expansions representing the reproducing kernels. Also we find the number of zeroes of the exact Bergman kernel via parallel slit domain in order to relate the exact Bergman kernel to an extremal problem.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.22 no.11
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• pp.1555-1563
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• 1998

Heat transfer and pressure drop for ${\phi}10.07$ dry surface fin-tube heat exchanger with wave and wave-slit fins were measured for different fin spacings and number of tube rows. Longitudinal and transverse tube spacings of the heat exchangers are 21.65mm and 25mm respectively, and wave depth of wave fin is 1.5mm. The experiments were performed for 4 different fin spacings, 1.3, 1.5, 1.7 and 2.0mm, and the number of tube rows were 1,2 and 3 rows. The present results were compared with the previous results for the wave depth of 2mm. Also hydrophilic coated and bare fins were tested. Correlations for Colburn j-factor and friction factor were developed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.46 no.2
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• pp.115-125
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• 2010

In order to design the optimal escape vent for the coon strip shrimp pot, the tank experiments were conducted with the model pot of five different slit height and slit width, respectively. The optimal height and width of escape vent were determined to 20mm and 40mm by tank experiments, respectively. These were determined by the 50% selection carapace length which was denoted to 25mm in selectivity curve. The escape experiments were conducted to determine a number of escape vent with the original shrimp pot to be set the designed escape vent from 2 vents to 10 vents increasing at intervals of 2 vents in tank. The optimal number of escape vents denoted 8 vents. Therefore, to apply the escape vent in commercial shrimp pot will be efficient to reduce small size shrimps to catch.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.12
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• pp.1007-1017
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• 2003

An experimental study on the air-side pressure drop and heat transfer coefficient of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side heat transfer coefficients in the literature is not based on a consistent approach. This paper focuses on new method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry and wet surface heat transfer estimation in fin-tube heat exchanger having refrigerant on the tube-side. Results are presented as plots of friction f-factor and Colburn j -factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of 150∼250 kg/$m^2$s with air flows at velocity ranges from 0.3 m/s to 0.8 m/s.

• Journal of the Semiconductor & Display Technology
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• v.5 no.1 s.14
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• pp.1-4
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• 2006

Recently, Ball Grid Arrays(BGAs) are getting used more frequently for a package type. The connectors on a BGA consist of a large number of small solder balls in a grid shape on its bottom side. However, since balls of BGAs mounted on PCBs are not visible, inspection before mounting them is indispensable. High speed non-contact 3D measurement technologies are necessary far real-time measurement of ball height, the most important inspection item. In this paper, an accurate 3D data acquisition system for BGAs is proposed that can acquire 3D profile at high speed using a 3D smart camera and laser slit ray projection. Some clipping and morphological filtering operations are employed to remove spiky error data, which occur due to reflections from some ball area to camera direction.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.3
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• pp.220-229
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• 2003

An experimental study on the air-side pressure drop and heat transfer coefficient of slit fin-tube heat exchanger has been carried out. The data reduction methodology for air-side heat transfer coefficients in the literature is not based on a consistent approach. This paper focuses on new method of data reduction to obtain the air-side performance of fin-tube heat exchanger using R22 and recommends standard procedures for dry surface heat transfer estimation in fin-tube heat exchanger having refrigerant on the tube-side. Results are presented as plots of friction f-factor and Colburn j -factor against Reynolds number based on the fin collar outside diameter and compared with previous studies. The data covers a range of refrigerant mass fluxes of 150~250 kg/$m^2$s with air flows at velocity ranges from 0.6 m/s to 1.6 m/s.

• Journal of Bio-Environment Control
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• v.22 no.4
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• pp.408-412
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• 2013

This study was carried out to investigate damp injury caused by tomato coir bag culture and prevent that. The tomato variety was used 'Minichal', and tomatoes were grown in greenhouse. The nutrient solution based on Yamazaki Tomato Standard Solution was irrigated from one hour after sunrise to two hour before sunset. The slits for darainage were made in three types; I, L, and bottom slit type. The coir bag of I and L type had six slits of 15cm length, that of bottom slit type had three slits of 15 cm length. The weight of coir bag in 24 hours after saturation was 14.2 kg in I type, 13.8 kg in L type, and 12.8 kg in bottom slit type, but there was not significant difference. The weight of coir bag after one day irrigation was 14.5 kg, 14.2 kg, and 13.3 kg at L, I, and bottm slit type, respectively. This means that the moisture content of coir bag during cultivation was lowest in bottom slit type. The number of adventitious root on stem was 160, 170, and 53 at I, L, and bottom slit type, respectively. The dry weight of root and root length were highest at bottom slit type, compared to other treatment. The marketable yield was highest 26.5 kg/20 plant in bottom slit type. For increasing yield and preventing damp injury, bottom slit type was most effective at U type bed coir bag culture.

• Journal of Energy Engineering
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• v.16 no.1 s.49
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• pp.7-14
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• 2007

An experimental study is performed to investigate the effect of air-side heat transfer and friction on characteristics of finned tube heat exchanger under dry surface and wet surface conditions (RH 50%, 70%). Air enthalpy calorimeter is used to obtain the performance evaluation and analysis of a fined tube heat exchanger. Four finned tube heat exchangers with slit fin or plain fin are tested. The number of tube rows are 2 and 3, and the tube diameter is 7 mm. Air-side heat transfer and friction are presented in terms of j factor and friction factor. At dry surface condition, j factor decreases with increasing Re and j factor of 3 row is lower than that of 2 row. Also, the friction factor of a slit fin is larger than that of a plain fin. At wet surface condition, the heat transfer effect is more significant in the case of the slit fin than the plain fin and 2 row than 3 row. The j factor and friction factor are affected by humidity, tube row and fin configuration.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.285-291
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• 1991

A two-stage slit type virtual impactor based on the concept of the single stage virtual impactor has been designed, fabricated, and evaluated for the purpose of concentrating the suspended particles in the air with the size range of 1.8-4.5 .mu.m and handling large flow volume. Monodisperse methylene blue particles have been generated with vibrating orifice aerosol generator (VOAG). The separation efficiency and concentration efficiency have been measured by the UV-visible absorption spectrometry. Previous study for a single stage virtual impactor were used to determine the design parameters such as 50% cut-off sizes and dimensions of the two stage virtual impactor. The separation efficiency curve and 50% cut-off Stokes number(cut-off sizes) are not sensitive to the nozzle Reynolds number, but sensitive to the ratio between the minor flow rate and the total flow rate, The measured concentration efficiency was compared with the maximum concentration efficiency determined by the separation efficiencies of the first and the second stages. The differences between the measured and the maximum concentration efficiencies result from the wall loss due to the deposited particles on the internal walls inside the impactor.

• Journal of the Korean Society of Costume
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• v.65 no.3
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• pp.76-90
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• 2015

This is a basic study of the two remaining armors (artifacts number K2366, K2368) from the late Joseon dynasty that is part of the Korean costume collection, which is preserved in the Mission Museum of Saint Ottilien in Germany. The armor No. 1 (artifacts number K2366) is a coat-styled armor with brass studs. It has a U-shaped neckline with the non-overlapping collars and sleeve straight-lined inseam. The armor No. 1 has the Mu to the sides and is not back slit. Both its inner and outer material are padded with cotton. Leather mails are attached on the inner lining, and studs are attached on the outer lining to match the leather mails. For this reason, the armor No. 1 can be named MyeonPiGab (brass studded armor consisting of a cotton coat with internal leather mails). The outer material is faded to have the natural white, or antique white look and the patterns on it are indigo blue. The inner material is blue, but the original color is unknown since it is faded. The lotus blossoms and vine patterns are dyed on the surface of the outer material and a name is written on the inner material. The armor No. 1 was worn between the late 17th century and the 19th century. It is estimated that it was worn by military officers who were above the mid-rank in the end of the Joseon dynasty. The armor No. 2 (artifacts number K2368) is a coat-styled armor with brass studs and a low-cut U-shaped neckline. The armor No. 2 has a slit on the left armpit and a string around it. Studs are evenly attached on the armor. The iron mails are attached to the left chest area on its inner lining. It seems that it was designed with both formality and functionality in mind. The outer material is red flannel, the inner material is blue satin and the pads are cheesecloth. The side of its collars, cuffs, front lines, sidelines, back slit, and bottom lines are trimmed with fur. There are armors called "JeonCheolGap (brass studded armor consisting of a felt coat with internal iron mails)," which is similar to the armor No. 2, however, the similarities are limited because they are not made of the same material nor do they follow the same principle of nomenclature.