• The Journal of Korean Physical Therapy
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• 제4권1호
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• pp.13-18
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• 1992

Most of the electromagnetic agents used in physical therapy rely for their effects on tissue heating and photoreaction of the body. Infrared and untraviolet light on the other hand, owns its place in medicine because it produces direct photochemial reaction when it interacts with the body. This study was carried out to investigate and review for photoreaction of the akin. The results were an follows. 1. The effects of the infrared are heat production, increasing metabolism, increasing circulation, vasodilatation and pigmentation. 2. Directed photoreactions are divided into acute reaction and chronic reaction, and the acute reaction makes pigmentation from $290\~320nm$ of ultraviolet ray. 3. Ultraviolet ray formated pigmentations, which are melanoblasts excited from ultraviolet ray and received chemical stimulation, that make melanin granule. 4. If exposured with long duration, at ultraviolet ray, it makes skin thickening and epithelioma. 5. Indirected photoreaction is made by existenced hypersensitivity of photoreaction or lack of photodefence structure. 6. The phototoxic reactions are synthesized by chemical reaction of excitement from ultraviolet ray also this time analysis, synthesis and polymerization from energy of a circumferenced substance. 7. Sunscreen substances are P-amino benzoic acid and oxidate titan.

• 한국분말재료학회지
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• 제27권3호
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• pp.256-267
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• 2020

Metal additive manufacturing (AM) technologies are classified into two groups according to the consolidation mechanisms and densification degrees of the as-built parts. Densified parts are obtained via a single-step process such as powder bed fusion, directed energy deposition, and sheet lamination AM technologies. Conversely, green bodies are consolidated with the aid of binder phases in multi-step processes such as binder jetting and material extrusion AM. Green-body part shapes are sustained by binder phases, which are removed for the debinding process. Chemical and/or thermal debinding processes are usually devised to enhance debinding kinetics. The pathways to final densification of the green parts are sintering and/or molten metal infiltration. With respect to innovation types, the multi-step metal AM process allows conventional powder metallurgy manufacturing to be innovated continuously. Eliminating cost/time-consuming molds, enlarged 3D design freedom, and wide material selectivity create opportunities for the industrial adoption of multi-step AM technologies. In addition, knowledge of powders and powder metallurgy fuel advances of multi-step AM technologies. In the present study, multi-step AM technologies are briefly introduced from the viewpoint of the entire manufacturing lifecycle.

• 전기학회논문지
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• 제59권2호
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• pp.338-343
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• 2010

Low cost motor drives are being sought for high volume energy efficient home appliances. Key to the realization of such low cost motor drives is to reduce the power electronic converter in terms of its components, particularly the active devices, finding the motor with least complexity for manufacturing and a controller that could extract the desired performance from the machine and converter combination. These and other factors such as self-starting, speed control over a wide range and most of all the crowning aspect of a four quadrant operation with bare minimum number of controllable switch (or switches) remain as formidable challenges for low cost motor drive realization. In this paper, a four quadrant switched reluctance motor (SRM) drive with only one controllable switch is realized by using a two-phase machine. The theory and operation of the proposed four-quadrant SRM drive with the proposed control algorithm for its realization are described. The motor drive is modeled, simulated and analyzed to verify its feasibility for self-starting, speed control and for four quadrant operation and the simulation results are presented. Experimental results confirm the validity of the proposed control algorithm for four quadrant control of the SRM drive. The focus of the paper is mainly directed toward the control algorithm for realizing the four-quadrant operation of the two-phase SRM drive with a single controllable switch converter.

• 전력전자학회논문지
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• 제25권3호
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• pp.181-187
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• 2020

In this study, we propose a spherical flux concentration structure for omnidirectional wireless power transfer. Omnidirectional wireless power transfer technology is a method that can transmit power to a transmitter located in an arbitrary position in a two-dimensional or three-dimensional space. However, to improve the power transfer distance in a wireless power transfer system, the diameter of the coil or the number of windings must increase, thereby increasing the size of the transmitter. The proposed transmitter structure adds a ferrite core inside the transmitter coil so that the magnetic flux generated by the transmitter is directed toward the position of the receiver. As a result, the flux linkage and the mutual inductance increase. By implementing the omnidirectional wireless power transfer system using the proposed structure, the power transfer distance can be improved by 65% compared with the conventional system without increasing the size of the transmitter. Simulation shows that the proposed spherical flux concentration structure increases the mutual inductance of the omnidirectional wireless power transmission system.

• Journal of Microbiology and Biotechnology
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• 제18권7호
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• pp.1245-1251
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• 2008

Oxalate decarboxylases (OXDCs) (E.C. 4.1.1.2) are enzymes catalyzing the conversion of oxalate to formate and $CO_2$. The OXDCs found in fungi and bacteria belong to a functionally diverse protein superfamily known as the cupins. Fungi-originated OXDCs are secretory enzymes. However, most bacterial OXDCs are localized in the cytosol, and may be involved in energy metabolism. In Agrobacterium tumefaciens C58, a locus for a putative oxalate decarboxylase is present. In the study reported here, an enzyme was overexpressed in Escherichia coli and showed oxalate decarboxylase activity. Computational analysis revealed the A. tumefaciens C58 OXDC contains a signal peptide mediating translocation of the enzyme into the periplasm that was supported by expression of signal-peptideless and full-length versions of the enzyme in A. tumefaciens C58. Further site-directed mutagenesis experiment demonstrated that the A. tumefaciens C58 OXDC is most likely translocated by a twin-arginine translocation (TAT) system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.545-546
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• 2007

A hybrid system that uses a parallel combination of wind turbine and fuel cell is modeled. Wind energy source is characterized by its intermittent and variable nature. The output power generated by the fuel cell is stable and can be properly controlled. Therefore, fuel cell system can be added to the wind turbine system for the purpose of ensuring continuous power flow. Fuel cell helps to compensate power and regulate the frequency in power system. Simulation results show the effect of the hybrid system on power regulation. The excess power generated by the wind turbine was directed to an electrolyzer to generate hydrogen and the power deficit was compensated by the fuel cell.

• 한국기계가공학회지
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• 제20권1호
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• pp.16-24
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• 2021

A laser-engineered net shaping (LENS) process is a representative directed energy deposition process. Deposition characteristics of the LENS process are greatly dependent on the process parameters. The present paper preliminarily investigates deposition characteristics of Inconel 718 superalloy on S45C structural steel using a LENS process. The influence of process parameters, including the laser power and powder feed rate, on the characteristics of the bead formation and the dilution in the vicinity of the deposited region is examined through repeated experiments. A processing map and feasible deposition conditions are estimated from viewpoints of the aspect ratio, defect formation, and the dilution rate of the deposited bead. Finally, an appropriate deposition condition considering side angle, deposition ratio, and buy-to-fly (BTF) is predicted.

• 한국기계가공학회지
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• 제21권1호
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• pp.90-94
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• 2022

Metal 3D-printing technology enables the manufacture of complex features or internal structures, which is not possible in fabrication by conventional cutting methods. The most successful types of metal 3D printing have been powder bed diffusion and directed energy deposition, which use laser heads exploiting high-power laser sintering metal powder. In this study, a cost-effective optical design was proposed for a 2-kW-level fiber laser head. Only two commercial lenses, a beamsplitter and a window, are used in the laser head, satisfying the technological requirements. According to the optical design, the spot size was 2.54 mm, and the stand-off distance from the laser head was 295 mm. The intensity distribution was Gaussian. Thus, smooth power sintering was possible without any laser spot marks. Monte Carlo analysis was employed to verify the consistency of the optical performance under conventional assembly tolerance.

• 한국압력기기공학회 논문집
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• 제17권2호
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• pp.75-82
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• 2021

The 3D printing technology is one of the fourth industrial revolution technology that drives innovation in the manufacturing process, and should be applied to nuclear industry for various purposes according to the manufacturing trend change. In nuclear industry, it can be applied to manufacture obsolete items and new designed parts in advanced reactors or small modular reactors (SMRs), replacing the traditional manufacturing technologies. A gate valve body was manufactured, which was obsolete in nuclear power plant, using DED(Directed Energy Deposition) metal 3D printing technology after restoring design characteristics including 3D design drawing by reverse engineering. The 3D printed valve body was assembled with commercial parts such as seat-ring, disk, stem, and actuator for performance test. For the valve assembly, including 3D printed valve body, several tests were performed, including pressure test, end-loading test, and seismic test according to KEPIC MGG and KEPIC MFC. In the pressure test, hydraulic pressure of 391kgf/cm² was applied to 3D printed valve body, and no leak was detected. Also the 3D printed valve assembly was performed well in end-loading and seismic tests.

• 한국압력기기공학회 논문집
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• 제19권1호
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• pp.11-19
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• 2023

Additive manufacturing technology, called as 3D printing, is one of fourth industrial revolution technologies that can drive innovation in the manufacturing process, and thus should be applied to nuclear industry for various purposes according to the manufacturing trend change in the future. In this paper, we performed tensile tests of 3D printed stainless steel 316L as-built specimens manufactured by two types of technology; DED (Directed Energy Deposition) and PBF (Powder Bed Fusion). Their mechanical properties (tensile strength, yield strength, elongation and reduction of area) were compared. As a result of comparison, the mechanical properties of the PBF specimens were slightly better than those of DED specimens. In the same additive type of specimens, the tensile and yield strength of specimens in the X and Y direction were higher than those in the Z direction, but the elongation and ROA were lower.