• Journal of the Korean Academic Society of Industrial Cluster
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• v.1 no.1
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• pp.47-66
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• 2007

The progress of digital revolution leads to technology and industry infusion which make new products and new commodity markets in the existing industries. Under the circumstance of new innovation patterns in industries and globalization of the world, innovation firms adapt different evolution processes for different business situations. Technological innovation enhances the competitiveness of fins in the business world. This paper shows the researches on technological innovation which make constant economy growth in the knowledge based economy. And this paper also suggests the policy on technological innovation for the future growth of society. Main focus of this paper are as follows. First, the theoretical survey on technological innovation is reviewed. Second, the program and the supporting system for technological innovation in the USA and Europe are investigated. Third, the situation and problems of Korea is analysed. Fourth, strategy and suggestions on the development of technological innovation in the 21st century knowledge based economy is suggested through the window of cluster and regional economy development.

• Journal of Technologic Dentistry
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• v.41 no.4
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• pp.255-262
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• 2019

Purpose: Recently, the production technology of dental prosthesis using 3D Printer workpeices has been developed. However, the lack of information on the work processes and casting techniques of materials for 3D printing casting is expected to require research. Therefore, in this study, we intend to cast a Dental DLP 3D Printer workpiece, which is being commercialized, to identify its appearance and internal clearance, and to observe its castability. Methods: Castability of the 3D Printer workpiece was evaluated. The specimen is prepared in a cylindrical shape and in a 1 mm thick coping shape. The control specimen is made of wax and the experimental specimen is made of resin using two types of 3D printers. After casting, the appearance of the casting body was observed and the internal clearance of the coping was measured. Results: RP1 and RP2, cylindrical specimens, were partially cast or fin. When coping-type specimens were measured before casting, the internal clearance of PE2 was more accurate than that of PC and PE1. When coping-type specimens were measured after casting, CE1 was the most accurate in occlusal clearance and CE2n was the most accurate in axial clearance. Conclusion: 1. Exterior observations of the casting body indicated casting defects and fins. 2. Internal clearance observations show that the occlusal clearance of the castings is larger after casting, and the axial clearance of the castings is smaller after casting. 3. It is judged that the RP2 specimen is more likely to be applied for casting than the RP1 specimen.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.6
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• pp.644-652
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• 2013

This paper describes the development and field experiments of Manta-type Unmanned Underwater Vehicle (UUV). Various simulations for Manta UUV are performed by using the nonlinear 6-DOF motion of equations. Through this simulation we verified the motion performances of Manta UUV. To acquire the blueprint of Manta UUV, it was designed with the simulation results. The Manta UUV uses a Doppler Velocity Log (DVL), gyrocompass, GPS, pressure sensor and other minor sensors, applied to measure the motion, position and path of Manta UUV. For its propulsion and changing a direction in the underwater, one vertical fin and four horizontal fins are installed at the hull of UUV. The Manta UUV system was verified with motion and autonomous navigation test at field.

• Journal of Advanced Marine Engineering and Technology
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• v.41 no.1
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• pp.1-7
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• 2017

When implementing butt joint welding of two plates, it is useful to attach end-tabs made of a metal with high heat conductivity (e.g., copper) at the front and back sides of the welded plates to prevent the bead from rolling down and prevent defects that may occur at the tips of the weld zone. In this study, the fin shape, which is known to have good heat discharging characteristics by natural convection, has been applied to enhance the cooling performance of the end-tab. From both experiment and numerical analysis, it was confirmed that end-tabs with fin-shaped holes have better heat discharging performance than end-tabs without holes. Through thermal and fluid flow analysis, the cooling rates of end-tabs with different hole shapes were estimated in order to figure out characteristics of shape factor that are important for the heat discharging performance. As a result, we found that the structure including vertical fins with optimal fin gap was the best-performing shape.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.9
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• pp.719-726
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• 2015

One method of increasing the heat-transfer rate is to increase the heat-transfer area. In this study, we test a wide louver fin-and-tube heat exchanger with $P_t/P_l$ = 1.03, and we compare the results with those of a louver fin-andtube heat exchanger with $P_t/P_l$ = 0.6. The results obtained show that the heat-transfer capacities of the wide louver samples are larger (16% in one row, 29% in two rows, and 38% in three row samples) than those of the louver samples. Considering the area ratio of 2.17, the increase in the heat-transfer capacity is somewhat small. The reason for this may be due to the smaller heat-transfer coefficient and fin efficiency of the wide louver sample. The effect of the fin pitch on the j and f factors are not profounded. The j and f factors decreased as the number of tube rows increased. We compare the data obtained with existing correlations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.41 no.6
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• pp.381-387
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• 2017

Dehydrogenation from the hydrolysis of a sodium borohydride ($NaBH_4$) solution has been of interest owing to its high theoretical hydrogen storage capacity (10.8 wt.％) and potentially safe operation. An experimental study has been performed on the catalytic reaction rate and pressure drop of a $NaBH_4$ solution over both a single microchannel with a hydraulic diameter of $300{\mu}m$ and a staggered array of micro pin fins in the microchannel with hydraulic diameter of $50{\mu}m$. The catalytic reaction rates and pressure drops were obtained under Reynolds numbers from 1 to 60 and solution concentrations from 5 to 20 wt.％. Moreover, reacting flows were visualized using a high-speed camera with a macro zoom lens. As a result, both the amount of hydrogenation and pressure drop are 2.45 times and 1.5 times larger in a pin fin microchannel array than in a single microchannel, respectively.

• Journal of Power System Engineering
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• v.21 no.3
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• pp.93-101
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• 2017

In conventional adsorption chamber, adsorbent is embedded in between heat exchanger fins by wire mesh. This method impedes heat and mass transfer efficiency. So in this study, to improve the heat transfer performance of heat exchanger, a fin-tube exchanger was coated with FAPO (Ferroaluminophosphate) zeolite adsorbent. The fin-tube heat exchanger has a fin pitch of 1.8 mm with a variation of adsorbent coating thickness of about 0.1 mm, 0.15 mm and 0.2 mm. By varying cooling water temperature and chilled water temperature respecively, heat transfer rate and overall heat transfer coefficient were investigated. As a result, the heat transfer rate and overall heat transfer coefficient increase with decreasing cooling water temperature and increasing chilled water temperature. Under the basic conditions, the heat transfer rate of heat exchanger with 0.2 mm coating thickness is 11% and 43% higher than that of 0.1 mm and 0.15 mm, respectively. The overall heat transfer coefficient is $189.1W/m^2{\cdot}^{\circ}C$, it is two times lager than that of 0.1 mm.

• Solar Energy
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• v.13 no.2_3
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• pp.91-106
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• 1993

The purpose of this study was to investigate the enhancement of heat transfer coefficient in double pipe fluidized bed heat exchangers. The inner tube used a smooth tube and a finned tube equipped with longitudinal fins. The heat transfer coefficients between the heated tube and fluidized bed of alumina beads were calculated as a function of fluidized velocity in various particle sizes($d_p$=0.41, 0.54, 0.65, 0.77mm) and static bed heights($H_o$=50, 100, 150, 200, 250mm). The coefficient for finned tube is higher than for smooth tube. And the maximum increasing rate is 7.8 times in smooth tube and 12.9 times in finned tube.

• Korean Journal of Microbiology
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• v.30 no.3
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• pp.164-170
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• 1992

Haemorrhagic ulcer in cultured snakehead(Chann0 argus) is widespread in Korea during the summer season. Round haemorrhagic ulcers as the main symptom of this epizootic disease can be found on the skin of the head. body, as well as fins of this fish. This study was conducted to investigate the pathology of this disease. First. Aeromonas veronii. the dominant species. was isolated from diseased snakeheads. Then this bacterium was injected into healthy snakeheads hypodermically. Such injection was found to induce haemorrhagic ulcers very similar to those observed in naturally infected fish. One or two days afier the injection, a red spot developed around the injection site. and grew bigger to from a red area. This enlarged area then developed into haemorrhagic ulcer, accompanied by substantial skin loss. Within five days. muscle necrosis proceeded to the extent that a perforation was made between the injection site and the opposite side. The fifty per cent lethal dosage was found to be $1\times10^{5}$CFU/0.25 ml by intraperitoneal injection. The results of this experiment lead us to conclude that Arromonas veronii is a major bacterium which causes haemorragic ulcer in cultured snakcheads.

• Journal of computational fluids engineering
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• v.3 no.1
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• pp.82-88
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• 1998

As a par of a project related to the development of the design algorithm of a compact heat exchanger for the application of the electronic home appliances, the effect of the discreteness of the airflow boundary generated on the cooling fin surface on the heat transfer and pressure drop characteristics of the heat exchanger was studied numerically. In general, there are two critical design parameters seriously considered in the design of the heat exchanger; heat transfer rate(Q) and pressure drop coefficient(C/sub p/). Even though the higher heat transfer rate with lower pressure drop characteristics is required in a design of the heat exchanger, it is not an easy job to satisfy both conditions at the same time because these two parameters are phenomenally inversely proportional. To control the boundary layer thickness and its length along the streamline, the surface of the flat fin was modified to accelerate the heat transfer rate on the fin surface. To understand the effect of the discreted fin size(S/sub w/) and its location(S/sub h/) on the performance of the heat exchanger in the airflow field, the flat fin was modified as shown in Fig. 1. From this study, it was found that the smaller and more number of slits on the fin surface showed the higher energy diffusion rate. It means that the discreteness of the boundary layer is quite important on the heat transfer rate of the heat exchanger. On the other hand, if the fin surface configuration is very complex than needed, higher static pressure drop occurs than required in a system and it may be a reason of the induced aerodynamic noise in the heat exchanger.