• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2561-2564
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• 2003

Data mining is an effective method of the discovery of useful information such as rules and previously unknown patterns existing in large databases. The discovery of association rules is an important data mining problem. We have developed a new parallel mining called Distributed Frequent Pattern Tree (abbreviated by DFPT) algorithm on a distributed shared nothing parallel system to detect association rules. DFPT algorithm is devised for parallel execution of the FP-growth algorithm. It needs only two full disk data scanning of the database by eliminating the need for generating the candidate items. We have achieved good workload balancing throughout the mining process by distributing the work equally to all processors. We implemented the algorithm on a PC cluster system, and observed that the algorithm outperformed the Improved Count Distribution scheme.

• Korean Journal of Computational Design and Engineering
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• v.16 no.4
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• pp.268-276
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• 2011

The product-level carbon footprint (PCF) is a comprehensive and widely accepted metric for sustainable product development. However, since a full PCF study in general is time and cost intensive, it is not feasible for the product development team to synchronize the activity to the main product development process. In addition, the current dedicated life cycle assessment (LCA) tools for calculating PCF, separated from the main product data management systems, have limitations to provide timely PCF information for design decision makings and collaborations between design and environment engineers. This paper examines the possibility of the extension of the current product data model that can support the PCF calculation with PDM (Product Data Management) databases. The product data model can represent not only the content of products but also context or system information of the products. The product data model can be implemented as a PDM database that can satisfy the needs for handy and timely PCF calculations from the consistent product data for dynamic design decision makings and engineering collaborations.

• Culinary science and hospitality research
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• v.23 no.6
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• pp.57-69
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• 2017

In this quantitative research, it was enhanced to understand the impact of intrinsic motivation on creative process engagement by examining the significant role of psychological safety on intrinsic motivation. These relationships were examined by targeting the employees working full-time for five star deluxe hotels. Total number of 230 responses had been collected out of 250 cases requested and he number of 213 cases was used for the final analysis. The data were analyzed using structural equation modeling with SPSS 19.0 and AMOS 7 software program. The results suggested that psychological safety is significantly associated with intrinsic motivation. Furthermore, the hotel employees' problem identification, information searching & coding, and idea generation are affected by intrinsic motivation. That is, intrinsic motivation plays a significant role for each sub-factors of creative process engagement in the hotel industry. The theoretical and practical implications of these findings are established and related suggestion for formulating marketing strategy is well discussed.

• Journal of Information Processing Systems
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• v.12 no.2
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• pp.310-321
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• 2016

TCS_SHA-3 is a family of four cryptographic hash functions that are covered by a United States patent (US 2009/0262925). The digest sizes are 224, 256, 384 and 512 bits. The hash functions use bijective functions in place of the standard compression functions. In this paper we describe first and second preimage attacks on the full hash functions. The second preimage attack requires negligible time and the first preimage attack requires $O(2^{36})$ time. In addition to these attacks, we also present a negligible time second preimage attack on a strengthened variant of the TCS_SHA-3. All the attacks have negligible memory requirements. To the best of our knowledge, there is no prior cryptanalysis of any member of the TCS_SHA-3 family in the literature.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.3
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• pp.1193-1209
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• 2015

Network coding is promising to maximize network throughput and improve the resilience to random network failures in various networking systems. In this paper, the problem of providing efficient confidentiality for practical network coding system against a global eavesdropper (with full eavesdropping capabilities to the network) is considered. By exploiting a novel combination between the construction technique of systematic Maximum Distance Separable (MDS) erasure coding and traditional cryptographic approach, two efficient schemes are proposed that can achieve the maximum possible rate and minimum encryption overhead respectively on top of any communication network or underlying linear network code. Every generation is first subjected to an encoding by a particular matrix generated by two (or three) Vandermonde matrices, and then parts of coded vectors (or secret symbols) are encrypted before transmitting. The proposed schemes are characterized by tunable and measurable degrees of security and also shown to be of low overhead in computation and bandwidth.

• Journal of the Korea Society of Computer and Information
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• v.22 no.4
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• pp.17-24
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• 2017

In this paper, we propose an efficient dynamic workload balancing strategy which improves the performance of high-performance computing system. The key idea of this dynamic workload balancing strategy is to minimize execution time of each job and to maximize the system throughput by effectively using system resource such as CPU, memory. Also, this strategy dynamically allocates job by considering demanded memory size of executing job and workload status of each node. If an overload node occurs due to allocated job, the proposed scheme migrates job, executing in overload nodes, to another free nodes and reduces the waiting time and execution time of job by balancing workload of each node. Through simulation, we show that the proposed dynamic workload balancing strategy based on CPU, memory improves the performance of high-performance computing system compared to previous strategies.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.25 no.6
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• pp.1449-1453
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• 2015

Constrained IoT devices cannot achieve full coverage of software attestation even though the integrity of software is critical. The limited modification attacks on control flow of software aim at the shadow area uncovered in software attestation processes. In this paper, we propose a light-weight protection system that detects modification by injecting markers to program code.

• Ceramist
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• v.10 no.3
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• pp.7-14
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• 2007

PbS QDs in glasses have attracted much attention due to the potentials for near-infrared applications. Growth of PbS QDs in the glass is discussed and size of PbS QDs formed in the glass can be tuned by varying the thermal treatment conditions. Hyperbolic-band approximation and four-band envelope function provide good simulation of the exciton energies of PbS QDs. Absorption and photoluminescence of PbS QDs was tuned into $1{\sim}2{\mu}m$ wave-length regime with large full width at half maximum photoluminescence intensity (>160 nm). Photoluminescence intensity of PbS QDs in the glasses was closely related to size of quantum dots, temperature, excitation and defects. Decrease in temperature shifted the photoluminescence bands to shorter wavelength and switched the photoluminescence from darkened state and brightened state.

• Annual Conference of KIPS
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• 2006.05a
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• pp.153-156
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• 2006

본 논문에서는 H.264 표준화 기구인 Joint Video Team(JVT) 권고안의 정수 단위 화소 움직임 예측을 위한 Unsymmetrical-cross Multi-Hexagon-grid Search(UMHexagonS) 알고리즘에서 Uneven Multi-Hexagon-grid Search(UMHGS) 부분을 개선한 알고리즘을 제안한다. 제안하는 알고리즘은 이전 프레임의 동일위치 또는 상위 모드에서 이미 선택된 움직임 벡터(MV: Motion Vector)를 이용하여 신호 대 잡음 비(PSNR: Peak Signal to Noise Ratio) 및 평균 비트 율(Average Bitrates)을 유지하면서, 현재 매크로블록의 검색영역을 줄이는 것이 가능하다. 제안하는 알고리즘의 성능은 Full Search Block Matching Algorithm(FSBMA) 및 UMHexagonS 알고리즘의 integer pel 에 대한 SAD(Sum of Absolute Difference) 연산횟수로 비교평가 하였다. 그 결과, FSBMA 에 비하여 평균 97.64%, UMHexagonS 에 비하여는 평균 17.48%의 연산횟수를 감소시키는 우수함을 보였다.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.332-336
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• 2003

In this paper, we report the experimental results of the novel Soft-Switching DC-DC converter and synchronous rectifier The experimental converter, that has a output voltage 3.3V, output current 20A, maximum power of 66W, switching frequency of 100kHz and input voltage range of 44-52V, has been successfully implemented. As a result, in the entire voltage range the measured full load efficiency was above 90$\%$, and the output voltage was regulated at 3.3V within ${\pm}3{\%}$ tolerance.