• Ocean and Polar Research
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• v.25 no.3
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• pp.257-267
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• 2003

Deep-sea bottom photographs acquired in the Clarion-Clipperton fracture zone of the northeast equatorial Pacific were analyzed to reveal the controlling processes for the spatial variation of manganese nodule. The results show that regional-scale occurrence variations of manganese nodule are mainly controlled by primary productivity of surface water, sedimentation rate, and water depth (or carbonate compensation depth). As a result, the diagenetic accretion on nodules increases toward southwest while hydrogenetic accretion increases toward northeast. Considering the northwestward movement of Pacific Plate, this regional-scale variation of manganese nodule occurrence seems to be affected by oceanic environment during the active growth period (Oligocene-Miocene) of Pacific Plate.

• Korean Journal of Materials Research
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• v.16 no.2
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• pp.111-115
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• 2006

High-finned tubes have good thermal conductivity and have better cooling efficiency than plain tubes or low-fined tubes due to bigger air contact area. During high-fined tubes are manufactured by roll forming, the main technique is illustrated to optimizing primary material(copper pipe), optimized die matrix designing technique for roll forming, control manufacturing speed to develop productivity etc. In this study, a roll forming system was developed in oder to produce high-finned tube. Also a multi-step roll forming die was designed & built to produce high-finned tube that has over 10 mm fin height. And then, roll forming test using copper pipe was performed to produce high-finned tube. Roll forming process for producing highfinned tube was optimized by analyzing and adjusting misrostructure, hardness, and surface roughness of roll formed high-fined tube.

• Special Issue of the Society of Naval Architects of Korea
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• 2007.09a
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• pp.135-141
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• 2007

CSR(Common Structure Rules) enter into force on $1^{st}$ April 2006. Generally for double hull tankers of less than 150m in length, the Rules of the individual Classification Society are to be applied. Where high tensile stresses act through an intermediate plate, increased fillet welds or penetration welds are to be used longitudinal/transverse bulkhead primary support member end connections to the double bottom. If workers have begun to make used of established procedures between corrugated BHD and lower stool joint, first to welding on groove of face and then it has to gouging to blow on groove of root. So amount of man-hour increased, productivity secreased.

• Proceedings of the Korea Society for Industrial Systems Conference
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• 1996.10a
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• pp.29-48
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• 1996

Previous studies on user training have largely focused on assessing models which describe the determinants of information technology usage or examined theeffects of training, on user satisfaction, productivity, performance and so on. Scant research efforts have been made, however, to examine those effects of training by using theoretical models. This study presented a conceptural model to predict intention to use information technology and conducted an experimentto understand how training for computer skill acquisition affects primary variables of the model. The data were obtained from 32 student subjects of an experimental group and 31 students of a control group, and the information technology employed for this study was a university's electronic mail system. The study results revealed that attitude toward usage and perceived behavioral control helped to predict user intentions ; outcome expectations were positively related to attitude toward usage ; and self-efficacy was positively related to perceived behavioral control. Thd hands-on training for the experimental group led to increases in perceived ease of use, self-efficacy and perceived behaviroal control. The changes in those variables suggest more causal effects of user training than other survey studies.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2000.10a
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• pp.550-556
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• 2000

Three floating islands were constructed on the surface of the reservoir, each consisting of 10 16-㎡ (4${\times}$4 m) segments, made of wood frames and floats. Three species of aquatic macrophytes were planted in each island on June, 1998. Phragmites australis was considered as the suitable aquatic macrophyte for the floating islands since it maintained the most efficient root and shoot balance among the macrophytes. The net primary productivity of P. Australis was 3,604 g/㎡ based on dry weight in 1999, with uptake rates of nitrogen and phosphorus estimated at 77.4 g/㎡/yr and 5.7 g/㎡/yr, respectively. The result of water quality simulation for the floating islands showed that, through adsorption of nutrients and light screening, they could reduce the amount of phytoplankton, thereby decreasing COD concentration.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1999.10c
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• pp.645-650
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• 1999

Three floating islands have been constructed for water quality improvement for a polluted irrigation reservoir. Phragmites australis was considered as the suitable aquatic macrophyte of the floating island. From April to August in 1999, the net primary productivity of Phragmites australis was 3,530gDM/㎡. Uptake rates of nitrogen and phoshorous by Phragmites australis planted in the floating island could be estimated to 10.2kg/d/ha and 0.8kg/d/ha, respectively. The floating islands worked well as a habitat of fish and prawns. Therefore, the floating islands could be evaluated a good measure ofwater quality improvement for irrigation reservoir.

• Korean Journal of Computational Design and Engineering
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• v.6 no.4
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• pp.215-221
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• 2001

In the zigzag milling of a pocket having islands, tool retraction is one of the primary factors that decrease productivity. Therefore, tool path with minimum number of tool retraction has been needed. Most researches about this topic have been concentrated on obtaining the optimum solution formulated through the geometric reasoning off pocket. Recently, several attempts were made to simplify this problem into region partitioning in order to get the numerically expressed minimum solution. In this research, a method reducing the number of tool retractions extended from existing region partitioning is provided. Applying the segment that is normal to the reference direction of zigzag milling, region partitioning is carried out and structural elements of the region are searched via graphs of islands and characteristic points. Through the processes presented, the number of region partitioned is less than that of existing processes.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.474-480
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• 2002

Aspheric optical lenses and mirrors are widely used in recent. It is more difficult to manufacture and measure the aspherical optics compared to conventional spherical ones. The interferometric optical test is common for the measurement of spherical optical surface. But the application of the interferometry to the measurement of aspheric surface is difficult because it needs a precise null corrector and very careful environmental conditions such as keeping constant temperature, humidity, atmospheric pressure and vibrations. To enhance productivity of optics manufacturing on-machine measurement and correction has been developed in this study. For practical applications, robustness of the measurement method to environments is more important. For the purpose an optical OMM(On-Machine Measurement) system has been developed using Shack-Hartmann test which has robustness to the environment. The wavefront has been reconstructed from the measured data using the primary aberration polynomial function by least square fitting. The measured result of the developed only system gives the maximum deviation only in 200 nm from the result measured by a commercial Fizeau interferometer Wyko 6000.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.96-102
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• 2008

Manufacturing of printed electronics using printing technology has begun to get into the hot issue in many ways due to the low cost effectiveness to existing semi-conductor process. This technology, with low cost and high productivity, can make it possible to produce printed electronics such as TFT, solar cell, RFID Tag, printed battery, and so on. In this study, apparatus of gravure-offset printing are developed for fine line-width/gap printing and the results obtained from the apparatus shows that it is possible to make around 20 micro-meter line-width/gap printing patterns. The roll-to-roll printing system for fine line-width printing based on primary experiment is presented. The printing results obtained from the system shows around 30 micro-meter line-width/gap printing patterns.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2017.11a
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• pp.84-85
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• 2017