• Proceedings of the KIEE Conference
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• 2001.10a
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• pp.258-261
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• 2001

High Power factor Active Filter converter is used for Inverter Air conditioner power supply to meet IEC standard. In the active filter topology for power factor, extra switch just control the input current indirectly to meet the IEC standard for reducing the cost and size. In this paper, low cost converter was suggested by simulation using extra switch which auxiliary pulse is inserted and quasi resonant soft switching topology control is adapted for panel's inverter air conditioner converter Inserting auxiliary Pulse method to the extra switch has the benefit of reducing THD by low cost input control circuit. And also quasi resonant soft switching topology can reduce switching loss. So both technical is suitable for Panel's Air conditioner.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.1
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• pp.6-11
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• 2003

The multi layer spiral inductors, which enhance the quality factor Q of an inductor fabricated on the silicon substrate, has been designed using a TSMC CMOS 0.2sum 1-poly 5-metal layer technology. To investigate the performance of the designed inductors, a 2.5-dimensional field simulation tool(Momentum) is used. The simulation results show that the quality factor Q of the 5-metal inductor is improved 1.8 times over that of a convention31 spiral inductor at 2GHz for wireless LAN applications.

• Proceedings of the KIEE Conference
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• 2002.06a
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• pp.6-8
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• 2002

Generally in solar air conditioning system, the diode rectifier is used to build up DC link voltage from AC source. The diode rectifier is simple and cheap but it brings out the problems of low power factor and plentiful harmonics at the AC source. Also It can degrade the utilization rate of solar energy because the reverse of power flow cannot be made. Hence, in this paper to overcome the peak power problems in summer and to endure good AC input characteristics, solar air conditioning system using the PWM converter is proposed. A high input power factor of 97[%] and an efficiency of 98[%] are also obtained. The harmonic guide lines of proposed rectifier is no interfered with inverter switching, resulting in a simple, reliable and low cost ac to dc converters in comparison with the boost type current improving circuits.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.251-254
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• 2000

This paper was to measure the structure, electric characteristics of 0.05Pb($(Al_{0.5}Nb_{0.5})$) - 0.95Pb$(Zr_{0.52}Ti_{0.48})O_3$ ceramics dopped with Cr+Fe. The results of this paper were gotten such as follows; The dielectric constants were decreased with Cr+Fe. The dielectric loss was minimum value of 1.008[%], dopped with Cr+Fe O.9[wt%] at 1200[$^{\circ}C$], In case of sintering at 1150[$^{\circ}C$], electromechanical factodkp) was maximum value of kp 42.73[%], at Cr+Fe 0.9[wt%]. The mechanical quality factor(Qm) was maximum value at Cr+Fe 1.2 [wt%], Also, in case of dopped with Cr+Fe, it make a improvement in temperature coefficient of resonant frequency at 0.3[wt%], 1150[$^{\circ}C$].

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.4
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• pp.551-560
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• 2010

In this paper, we suggest a localization method of factors affecting the accuracy of Air-to-Ground weapon delivery. The proposed method, called FBEL(Factor-Based Error Localization), is based on the fault localization technique widely utilized in the realm of software engineering field. FBEL localizes the major factors affecting the performance of weapon delivery. To analyze the effectiveness and the applicability of FBEL, we applied FBEL to real firing data and got the major factors caused the errors. We expect that the method could contribute to improve the quality of weapon delivery system. We also expect that it may aid improvement of pilot capability greatly, if it is applied to pilot firing training.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1506-1508
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• 2005

VCO(voltage controlled oscillator) using mobile communication device decides direct characteristics as parts that affect important in stable oscillation and distortion characteristics of system. VCO used 900 MHz band was designed by the transformation of Colpitts circuit form use ADS that consider Q-factor to minimize phase noise. VCO manufactured together evaluation board and voltage control oscillator to FR-4 PCB. VCO experimented chracteristics after control through resonance department tuning. In our research, the designed VCO has 15.5 dBm output level at the bias condition of 6V and 10mA and the operating frequency range of 917 MHz$\sim$937 MHz band. Phase noise is -98.28 dBc/Hz at 1 MHz frequency offset from the carrier.

• International Journal of Computer Science & Network Security
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• v.21 no.9
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• pp.346-353
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• 2021

In this proposal, we aim to enhance the security of systems accounts by improving the authentication techniques. We mainly intend to enhance the accuracy of the one-time passwords via including voice biometric and recognition techniques. The recognition will be performed on the server to avoid redirecting voice signatures by hackers. Further, to enhance the privacy of data and to ensure that the active user is legitimate, we propose to periodically update the activated sessions using a user-selected biometric factor. Finally, we recommend adding a pre-transaction re-authentication which will guarantee enhanced security for sensitive operations. The main novelty of this proposal is the use of the voice factor in the verification of the one-time password and the various levels of authentications for a full-security guarantee. The improvement provided by this proposal is mainly designed for sensitive applications. From conducted simulations, findings prove the efficiency of the proposed scheme in reducing the probability of hacking users' sessions.

• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.218-227
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• 2011

The objective approach for assessment of stream naturalness is an essential part of the stream restoration project. This study proposes the methodology for the assessment of stream naturalness considering physical, biological and chemical factors. Physical factors consists of riffle and pool, river bed material, bank protection, floodplain vegetation and levee materials; biological factors are benthic macroinvertebrate, KSI (Korean Saprobic Index), and IBI (Index of Biological Integrity) and chemical factors are pH, DO (dissolved oxygen), and TP (total phosphorus). This procedure is applied to the Mokgamcheon. As a result, the downstream of Mokgamcheon (zone I) needs the prompt improvement of stream naturalness, compared to the others (zone II and III). This evaluation technique will be an effective tool to quantify the stream naturalness and can be used to set the target of stream restoration project.

• Medical Lasers
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• v.8 no.2
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• pp.94-96
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• 2019

Burns are one of the most extensive injuries of soft tissues as well as skin, occasionally resulting in extensive, deep wounds and death. Burn wounds can lead to severe physical and psychological distress because of excessive scarring and skin contractures. Treatment of burn wounds has always been a challenging problem and many different methods have been used to treat such injuries. We report here on treating a patient with a burn wound using 830-nm light emitting diode (LED) phototherapy combined with epidermal growth factor (EGF) solution. After five daily sessions of LED with EGF solution treatment, the patient demonstrated nearly complete improvement with no remarkable side effects. We suggest that LED phototherapy combined with EGF solution could be an effective and safe treatment option for treating burn wounds.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.103-110
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• 2022

In the era of the 4th Industrial Revolution, smart technology being considered to improve productivity breakthroughs is in the spotlight as a means to replace traditional construction technology in the construction industry. However, various problems are occurring in construction sites using smart technology and causing negative impacts on construction projects. Therefore, the objective of this study is to identify risk factors that occur when smart technologies are used in construction projects. To achieve this purpose, this study investigated the difficulties at construction projects using smart technology, and risk factors were derived based on site surveys and literature. The risk factors were measured by experts, and then a total of 19 risk factors was derived by exploratory factor analysis. As a result, risks were classified as 5 factors, the institutional factor is the most difficult response, and the government needs anticipative system improvement and a long-term plan. The research findings provide practical implications for construction experts trying to apply smart technology in construction sites and construction policy-makers to revitalize smart technology.