• Proceedings of the Korean Information Science Society Conference
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• 2004.04b
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• pp.46-48
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• 2004

차량항법장치(Car Navigation System ： CNS)나 지리정보시스템(Geographic Information System ： CIS)에서 공간 객체를 효율적으로 다루는 색인기법에 대한 다양한 논의가 있어왔다 기존의 방법에서는 공간 객체의 인접성(cluster)과 밀집성 만을 고려해서 색인 트리를 생성하므로, 편향된 접근 빈도론 가진 공간 객체이 대해서 효과적인 탐색시간을 제공하지 못한다. 접근 빈도를 반영한 색인 기법은 공간 데이터가 갖는 특성-2개 이상의 차원에 대한 순서 할당이 불가능-에 의해서 지리적으로 인접된 객체들을 묶지 못하고, 이로 인해서 공간 객체에 대한 효율적인 색인 기법을 제공할 수 없다. 지리 데이터에 대한 위치와 접근 빈도가 주어질 매, 색인 트리는 좌표 정보뿐 아니라 공간 객체에 대한 접근 빈도도 고려해서 생성되어야 한다 본 논문에서 제안하는 기법을 전체 영역을 세부영역으로 분할하고, 각 세부 영역에 대해서 편향색인 트리를 생성한 뒤에 트리를 병합함으로써 밀집도와 접근 빈도를 반영한, 편향된(skewed) 색인 트리를 생성하도록 한다. 편향된 색인 트리는 접근 빈도가 높은 공간객체를 상위계층(level)에 위치시킴으로써 탐색비용을 줄인다.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.11a
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• pp.537-539
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• 2012

영상신호처리와 같이 공간적 신호처리를 하는 실시간 신호처리시스템에서는 서로 다른 입출력 순서를 갖는 특정 크기의 블록 단위 신호처리가 요구된다. 다양한 영상압축코덱에 쓰이는 엔트로피 코딩을 위한 데이터 재정렬이 대표적인 예이다. 이 경우 동일 주소에 데이터를 읽고 쓰는 단일 버퍼링 방법이 저장 공간을 최소화 하는 최적의 방법이지만 상이하고 불규칙한 입출력 순서를 갖는 경우 이 방법을 적용할 경우 불규칙한 순서열이 이어지기 때문에 구현하기 어렵고 두 배의 저장 공간을 소모하는 이중 버퍼링 방법을 주로 사용한다. 본 논문에서는 불규칙한 순서열 변화를 보이는 임의의 상이한 입출력 순서를 갖는 동시 입출력 동작에서도 예측가능한 유한한 횟수 안에 규칙적인 반복성이 나타남을 입증하고 자원을 최소화하는 단일 버퍼링 방법이 적용될 수 있음을 보였다.

• East Asian Economic Review
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• v.22 no.4
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• pp.427-465
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• 2018

East Asia, for long the epitome of successful engagement in trade, faces serious challenges: technological change that may threaten the very model of labor intensive industrialization and a backlash against globalization that may reduce access to important markets. The analysis in this article suggests that how East Asia copes with these global challenges will depend on how it addresses three more proximate national and regional challenges. The first is the emergence of China as a global trade giant, which is fundamentally altering the trading patterns and opportunities of its neighbors. The second is the asymmetric implementation of national reform - in goods trade and investment versus services - which is affecting the evolution of comparative advantage and productivity in each country. The third is the divergence between the relatively shallow and fragmented agreements that regulate the region's trade and investment and the growing importance of regional and global value chains as crucial drivers of productivity growth.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.33 no.2
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• pp.235-242
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• 2023

ORAM(Oblivious RAM) is an algorithm that defends side channel attacks when the user uses an untrusted server or hardware. ORAM defends against leaks of information by hiding data access patterns. However, ORAM is not in practical use because as ORAM reinforces hardware security, it also has a severe disadvantage in processing speed. In this paper, we suggest using newly introduced hardware, PIM (Process In Memory), to accelerate ORAM and use it practically.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.9
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• pp.2529-2549
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• 2023

For effectively lowering down the risk of cyber threating, the zero-trust architecture (ZTA) has been gradually deployed to the fields of smart city, Internet of Things, and cloud computing. The main concept of ZTA is to maintain a distrustful attitude towards all devices, identities, and communication requests, which only offering the minimum access and validity. Unfortunately, adopting the most secure and complex multifactor authentication has brought enterprise and employee a troublesome and unfriendly burden. Thus, authors aim to incorporate machine learning technology to build an employee behavior analysis ZTA. The new framework is characterized by the ability of adjusting the difficulty of identity verification through the user behavioral patterns and the risk degree of the resource. In particular, three key factors, including one-time password, face feature, and authorization code, have been applied to design the adaptive multifactor continuous authentication system. Simulations have demonstrated that the new work can eliminate the necessity of maintaining a heavy authentication and ensure an employee-friendly experience.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.3
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• pp.997-1005
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• 2010

Recently, there has been a growing interest in the use of WLAN technology due to its easy deployment, flexibility and so on. Examples of WLAN applications range from standard internet services such as Web access to real-time services with strict latency/throughput requirements such as multimedia video and voice over IP on wireless network environments. Fair and efficient distribution of the traffic loads among APs(Access Points) has become an important issue for improved utilization of WLAN. This paper focuses on an AP selection scheme for achieving better load balance, and hence increasing network resource utilization for each user on wireless network environments. This scheme makes use of active scan patterns and the network delay as main parameters of load measurement and AP selection. This scheme attempts to estimate the AP traffic loads by observing the up/down delay and utilize the results to maximize the link resource efficiency through load balancing. We compared the proposed scheme with the original SNR(Signal to Noise Ratio)-based scheme using the NS-2(Network Simulation.2). We found that the proposed scheme improves the throughput by 12.5% and lower the network up/down link delay by 36.84% and 60.42%, respectively. All in all, the new scheme can significantly increase overall network throughput and reduce up/down delay while providing excellent quality for voice and video services.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.5
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• pp.94-101
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• 2013

The market for NAND flash-based storage devices has grown significantly as they rapidly replace traditional disk-based storage devices. Heterogeneous NAND flash-based storage devices using both multi-level cell (MLC) and single-level cell (SLC) NAND flash memories are also actively researched since both types of memories complement each other. Heterogeneous NAND flash-based storage devices suffer from the overheads incurred by migration from SLC to MLC and garbage collection of SLC. This paper proposes a new flash translation layer (FTL) for heterogeneous NAND flash-based storage devices to reduce the overheads by utilizing SLC efficiently. The proposed FTL analyzes the access patterns of logical blocks and selects and stores only logical blocks expected to bring performance improvement in SLC. The experimental results show that the total execution time of heterogeneous NAND flash-based storage devices with our proposed FTL scheme is 35% shorter than that with the previously proposed best FTL scheme.

• Journal of KIISE:Computer Systems and Theory
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• v.32 no.7
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• pp.349-358
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• 2005

False sharing is a result of co-location of unrelated data in the same unit of memory coherency, and is one source of unnecessary overhead being of no help to keep the memory coherency in multiprocessor systems. Moreover. the damage caused by false sharing becomes large in proportion to the granularity of memory coherency. To reduce false sharing in a page-based DSM system, it is necessary to allocate unrelated data objects that have different access patterns into the separate shared pages. In this paper we propose call-site tracing-based shared memory allocator. shortly CSTallocator. CSTallocator expects that the data objects requested from the different call-sites may have different access patterns in the future. So CSTailocator places each data object requested from the different call-sites into the separate shared pages, and consequently data objects that have the same call-site are likely to get together into the same shared pages. We use execution-driven simulation of real parallel applications to evaluate the effectiveness of our CSTallocator. Our observations show that by using CSTallocator a considerable amount of false sharing misses can be additionally reduced in comparison with the existing techniques.

• Journal of The Korean Society of Grassland and Forage Science
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• v.33 no.4
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• pp.290-297
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• 2013

This study was carried out to investigate the effects of a by-product feed-based silage (BF silage) feeding on behavior patterns of growing Hanwoo steers. A total of 10 Hanwoo steers (11 months old, 302kg of body weight) were assigned to 2 dietary treatments: the control (concentrate mix + free access to rice straw), and the treatment (concentrate mix + free access to BF silage). The behavior patterns were observed for 48 hours. The intakes of dry matter (DM) and neutral detergent fiber (NDF) of the treatment group were higher than those of the control group. Eating time, ruminating time and resting time were not different between the control and treatment. But, the intake time per kg DM was higher for the control than treatment. The number of bolus, total chewing frequency, number of ruminating per bolus and number of bolus per minute were not different between the control and treatment. But the chewing frequency per bolus was higher in the treatment than control (p<0.05), and feed value index was lower in treatment than control (p<0.05). Frequencies of drinking and defecating were not different between the two groups, but the frequency of urinating was higher for the treatment (p<0.05) than control. Eating rate, ruminating efficiency and chewing efficiency were much higher in the treatment group than control (p<0.05). These results indicate that the replacement of conventional rice straws with the BF silage (physically effective NDF, about 25%) did not affect the ruminating behaviors of Hanwoo steers significantly.

• The Korean Journal of Archival Studies
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• no.43
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• pp.71-102
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• 2015

The present study aims at investigating the current usage patterns of Korean Standard Records Management System. The Korean Standard Records Management System has been designed and distributed by the National Archives Korea in order to support records management of public agencies. An email survey has been sent to 4 types of public agencies: central government agencies, provincial governments, provincial education offices as well as city and county offices. While all agencies are included in the survey for the first three types, only two provincial districts are selected for city and county offices, Out of 101 email questionnaires sent, 65 are returned(63.73%). The results show the usage patterns of 240 functionalities aligned to 9 main functions: accession from records creators, preservation, appraisal, accession to the national archives, reference management, access and tracking, retrieval and use, system management as well as freedom of information management by public institutions. Since its launch in 2007, the system has been distributed to 707 public agencies as of late 2014. The problem is that there has been no attempt to evaluate the functionalities and usabilities of the system. Only grievances from those agencies implemented the system have never been ceased. The present study is expected to offer the levelled ground for productive discussion between the national archives and the agencies.