• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.198-200
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• 2018

In this paper a single-stage single-phase differential type isolated AC-DC converter is proposed. This converter eliminates the requirement to use bulky electrolytic capacitor from the system and at the same time provides DC charging by employing the AC Power Decoupling waveform control method. All the switches of the converter achieve ZVS turn on during half line cycle and all diodes achieve ZCS turn off during entire line cycle. A conventional controller is implemented for PFC control and output regulation, whereas a power decoupling controller is added to compensate $2^{nd}$ harmonic ripple power. In addition, an interleaving technique is applied to increase the power range of the converter and reduce the input inductor size. In the end simulation verification is performed and results are obtained for 6.6KW.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.191-192
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• 2014

Multiple output converters (MOCs) are widely used for applications which require various levels of the output voltages due to their benefits in cost, volume, and efficiency. However, most of the MOCs developed so far can regulate only one output tightly and require as many secondary windings in the transformer as the number of the outputs. In this paper, a novel Time Division Multiple Control (TDMC) method to regulate all the outputs in high precision is proposed and applied for the multiple output battery charger based on the phase shift full bridge topology to charge a multiple number of batteries at one time. The proposed converter can charge three different kinds of batteries or same kind of batteries in different state of charges (SOCs) by using constant current/constant voltage (CC/CV) charge mode independently. At the same time it can provide an even degree of tight regulation for each output to satisfy the strict ripple requirement of the battery. The validity and feasibility of the proposed method are verified through the experiments.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.12
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• pp.453-460
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• 2022

As high-performance quantum computers are expected to be developed, studies are being actively conducted to build a post-quantum security system that is safe from potential quantum computer attacks. When the Grover's algorithm, a representative quantum algorithm, is used to search for a secret key in a symmetric key cryptography, there may be a safety problem in that the security strength of the cipher is reduced to the square root. NIST presents the post-quantum security strength estimated based on the cost of the Grover's algorithm required for an attack of the cryptographic algorithm as a post-quantum security requirement for symmetric key cryptography. The estimated cost of Grover's algorithm for the attack of symmetric key cryptography is determined by the quantum circuit complexity of the corresponding encryption algorithm. In this paper, the quantum circuit of the SCHWAEMM algorithm, AEAD family of SPARKLE, which was a finalist in NIST's lightweight cryptography competition, is efficiently implemented, and the quantum cost to apply the Grover's algorithm is analyzed. At this time, the cost according to the CDKM ripple-carry adder and the unbounded Fan-Out adder is compared together. Finally, we evaluate the post-quantum security strength of the lightweight cryptography SPARKLE SCHWAEMM algorithm based on the analyzed cost and NIST's post-quantum security requirements. A quantum programming tool, ProjectQ, is used to implement the quantum circuit and analyze its cost.

• Journal of Korean Society of Rural Planning
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• v.19 no.1
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• pp.91-107
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• 2013

In recent years, the number of walking-tourists who visit Jeju olle trail are increasing every year and the ripple effect is a rapid change on the roles and leadership of local people in rural villages. The reason for the change is that most Jeju Olle Trails cuts through the rural village in Jeju island. However, most of travelers just walked along the trails, no one was interested about villages along the Olle roads. For these reasons, many rural villages would not get any benefits such as non-farm income, sales profit and also can not activate the facility of village and infrastructure. Therefore, we study on Revitalization Method for rural villages through the Analysis of characteristics of tourist in Jeju Olle Trails and a field survey research too. In this process, we investigated the status and characteristics of the rural villages of Jeju island in the first step. Then, we considered the distinct characteristics and factors for improving of the 10 places with site investigation where were recommended by Jeju Olle Corporation and Jeju Agricultural Technology Center in second step. Lastly, we arranged the resident's requirement and result of survey and interview with leaders of rural village. As a result, we suggest the activation methods for residents and leaders of rural area and this study is also expected to help management of rural villages and also is an important study to improve importance of utilizing of more people visiting in Jeju Olle Trails.

• Journal of Korea Technology Innovation Society
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• v.14 no.4
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• pp.1024-1049
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• 2011

Korea has accomplished rapid industrial development based on the manufacturing industry. However, the growth potential has been slowing down lately due to some reasons including low employment creation rates. Also, competitions in the manufacturing industry with China and developing countries in Asia are constantly intensified. Advanced countries maintain economic growth based on the competitiveness secured by changing its industrial structure into service oriented economy. Accordingly Korean government announced various policies to promote service industry and stimulate R&D activity for the advancement of knowledge based service industry. For promoting R&D of private firm, R&D center accreditation system for knowledge based service firm is going to be introduced. However, the accreditation system needs to be revised because it was established based solely on manufacturing business. Under the existing system, subject firms for government support are selected based on R&D activities. However in service area, the difference between R&D activity and business activity is indistinctive due to its nature so that the range of subject firms can be expanded too much. So it is more practical to select major service businesses and operate the system with selected businesses. There also should be proper logic to select major service business from the whole service businesses. We have to consider Koean industrial structure which is heavily dependent on manufacturing business and has weak competitiveness in service business when preparing the logic. In this paper, we study how to set up the range of service business and the requirements for R&D center accreditation. For this, this paper analyzed the ripple effect on the economy of service businesses based on input-output analysis, R&D activity and capability to put the resource for R&D. Based on the analysis result, we suggest methods to screen subject companies for R&D center accreditation among service business and present possible measures on manpower and physical requirement for service industry's R&D center accreditation system.