• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.52-59
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• 2015

Cross-cut disks from small diameter oak logs were thermally modified and developed to make accessories such as a brooch. However it is known that domestic oaks are refractory and it is hard to dry their cross-cut disks without any drying defects. The cross-cut disks of Quercus variabilis (7 mm long in the longitudinal direction) were forced to dry in air at two different air velocities in summer and fall season, and their drying yields were investigated. Under the same condition, the average final moisture contents (MCs) of the specimens dried in the fall were lower than those dried in the summer. The average final MCs of the small diameter specimens dried at higher air velocity were slightly lower than those at lower air velocity while those of the large diameter specimen were not influenced by the air velocity. The number of the large diameter specimens with cross checkings was higher than that of the small diameter specimen. This discrepancy between two different diameters was twice in the fall, while it was more than four times in the summer. The large diameter specimens dried at low air velocity in Summer were cross-checked most, which was attributed to repeated water condensation and evaporation due to high humidity and low air velocity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2000.06a
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• pp.19-27
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• 2000

High speed machining (HSM), specifically end milling and ball end cutting, is attracting interest in the die/mold or aerospace industries for the machining of complex 3D surfaces. HSM of difficult-to-cut materials such as die/mold steels, titanium alloys or nickel based superalloys generates the concentrated thermal/frictional damage at the cutting edge of the tool and rapidly decreases the tool life. Following a brief introduction on HSM and reated aerospace or die/mold work, the paper reviews published data on the effect of cutter/workpiece orientation and cutting environments on tool performance. First, experimental work is detailed on the effect of cutter orientation on tool life, cutting forces, chip formation, specific force and workpiece surface roughness. Cutting was performed using 8 mm diameter PVD coated solid carbide cutters with the workpiece mounted at an angle of 45 degree from the cutter axis. A horizontal downwards cutting orientation proveded the best tool life with cut lengths ∼50% longer than for all other directions (horizontal upwards, vertical downwards, vertical upwards). Second, the cutting environments were investigated for dry, flood coolant, and compressed chilly air coolant cutting. The experiments were performed for various hardened materials and various coated tools. The results show that the cutting environment using compressed cilly air coolant provided better tool life than the flood coolant or the dry.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.529-533
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• 1996

Recently, manufacturing industries are doing their best to increase productivity and to reduce production time. One of tile efforts is to develop user-friendly and effective CAM systems. For this purpose, a CAM system for turning was developed. In the developed system. user interacts with tile CAM system using graphical user interface (GUI) and manufacturing support functions to make NC programs effectively. Manufacturing support functions include cycle decoder. interference check be ween tool and workpicce. bar turning without air cut and dynamic/wireframe simulation. In the cycle decoder. basic options are provided to novices for their convenience. and advanced options are provided to help expert to modify the program using their knowledge. Interference check has been nil issue in tile CAM system for tuning. In this paper. when a user selects a tool. interference check between selected tools and workpieces is done automatically. Moreover. remaining shapes are calculated automatically. Then, tile CAM system requests user to input all additional tool and generates NC codes to cut tile remaining shapes. In bar turning of forged raw material, air cut should be prevented for effective machining. For this purpose, a new algorithm for bar turning was developed. Dynamic and wireframe simulation was used to verify the generated NC code.

• Proceedings of the KIEE Conference
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• 1989.07a
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• pp.579-582
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• 1989

The air-cooled waterwheel generator has a fan connected to waterwheel shaft or motor driven fan or fans. The fans are operated at constant speed, constant input, regardless of generator loss which is varied according to generator output and coolant the perature. Energy savings may he possible if the cooling air flow is controlled according to generato output and air temperature depending on season. The simulation and experience have been done on the 22.6 KVA Waterwheel generator by using AC variable speed drive. The results gave us los cut of generator.

• Journal of the Korean Society of Tobacco Science
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• v.27 no.2
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• pp.201-206
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• 2005

In this work, we studied the effects of the moisture contents of cut tobacco on loose end of cigarettes. The loose end of the cigarette groups decreased with the increase of moisture contents of the cut tobacco and especially the loose end of A and C groups decreased to $31\%\;and\;52\%$ with the increase of $1\%$ moisture contents. $A-13.5\%\;and\;B-14.0\%\;and\; C-14.0\%$ moisture samples showed the increase of the weight ratio of cut tobacco over 1.4mm cut length but the decrease under 1.4mm cut length. We concluded that the main reasons were regarded to reduction of small fragment tobaccos caused by increase of moisture contents and exception of air-suction transport of tobaccos to cigarette making machine. In spite of the moisture increase of cut tobaccos under fixed EPD(encapsulated pressure drop), the hardness of Band C sample groups were maintained constantly except A group. This result means that under fixed EPD, the weight of cut tobacco in cigarette rods increases to compensate the reduction of pressure drop by moisture increase of cut tobaccos.

• Journal of Power System Engineering
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• v.17 no.1
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• pp.58-63
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• 2013

The aerodynamic performance of double inlet sirocco fan is strongly dependent upon the design factors of impeller and scroll. In this paper, the change of scroll size was adopted to investigate the aerodynamic performances of double inlet sirocco fan and indoor PAC. Especially, a scroll expansion angle and a cut-off clearance ratio were considered to change the scroll size. In addition, the installation depth between double inlet sirocco fan and indoor PAC was considered. As a result, the total pressure efficiency of double inlet sirocco fan shows about 62%~73% according to the change of scroll expansion angles. Moreover, the flowrate performance of indoor PAC is the best at the condition of a scroll expansion angle of 8°, an installation depth of 15 mm and a cut-off clearance ratio of 8%.

• Proceedings of the Korean Geotechical Society Conference
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• 2003.03a
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• pp.481-484
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• 2003

Sulfide minerals contacted with air and water in coal seam cause oxidation reactions. This oxidation reactions make low pH of groundwater and surface water(Acid Drainage). The reddish brown precipitate collected from the cut slope of the study area was estimated using the X-Ray Diffractometer(XRD). XRD results show that the cut slope was affected by Acid Drainage. The cut slope exposured to Acid Drainage become weak about chemical weathering and defile the appearance of the road. Drainage facilities are very important in Cut Slope under Acid Drainage influence. Reactions between Coal seam and water cause chemical weathering and environmental problem. Therefore It is important to control the transfer paths of groundwater and surface water and to install water collecting facilities

• Journal of the Korean Wood Science and Technology
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• v.24 no.4
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• pp.87-92
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• 1996

When cutting 2.0cm-thick red oak and hard maple with an air-jet-assisted carbon-dioxide laser of 2kW output power, maximum feed speed at the point of full penetration of the beam decreased with increasing the angle between grain and cutting direction. Feed speed averaged 3.75 and 3.38 meters per minute for red oak and hard maple, respectively. Gray-level of laser-cut surfaces were analyzed by image analysis system. The highest gray level of laser-cut surface was obtained when red oak was cut parallel to grain by laser. Surface profiler was used to scan the sawn and laser-cut surfaces. Center line average roughnesses of laser-cut surfaces were higher than those of sawn surfaces. Scanning electron micrographs showed the cell walls which were melted by laser.

• Food Science and Preservation
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• v.22 no.1
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• pp.154-157
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• 2015

To maintain the freshness and to prevent browning of cut Kimchi cabbages, the effect of the cutting process using a ceramic knife under $N_2$ blowing on the quality of the cut Kimchi cabbages was investigated. Kimchi cabbages cut with a ceramic knife under $N_2$ gas blowing conditions (NC) were stored at $5^{\circ}C$ for 7 days, and their weight reduction ratio and the browning degree and appearance were compared with those of the control treatment samples (OS; cut with a stainless steel knife under normal air, OC; cut with a ceramic knife under normal air). The weight reduction ratios were 0.07~0.13%, and the NC treatment showed the lowest reduction ratio among all the treatments (p<0.05). The Hunter L values increased, but the a and b values decreased after 5-day storage in all the treatments. The NC treatment had higher L values but lower a and b values than the OS and OC treatments. The browning degrees by Hunter color value, PPO activity, and appearances were the least in the NC treatment (p<0.05). The cutting process with a ceramic knife under $N_2$ blowing could be applied to the cutting of vegetable products and for minimal fruit processing.

• Proceedings of the KIEE Conference
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• 1992.07b
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• pp.1045-1047
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• 1992

Photovoltaics is considered to be one of the most promising technologies which can greatly contribute to future energy supply because of a large, secure, essentially inexhaustible and broadly available resource - sunlight. However, recent progresses in photovoltaics make also possible its short-term practical application in some areas. Among them the solar air conditionner powered by photovoltaic system attracts considerable interest due to its main advantage which consists in the reduction of drastically increasing electricity peak load in summer season. In this review paper our current study on the solar air conditionner will be briefly summarized.