• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.12
• /
• pp.714-723
• /
• 2003

In order to guarantee system survivability against attacks based on new methodology, we need a solution to recognize important resources for essential services and to adapt the urgent situation properly. In this paper, we present a dynamic resource reallocation scheme which is one of the core technologies for the implementation of intrusion tolerant systems. By means of resource reallocation within a node, this scheme enables the essential services to survive even after the occurrence of a system attack. If the settlement does not work within the node, resource reallocation among nodes takes places, thus the essential services are transferred to another prepared server node. Experimental result obtained on a testbed reveals the validity of the proposed scheme for resource reallocation. This scheme may work together with IDS(Intrusion Detection System) to produce effective responsive mechanism against attacks.

• Journal of KIISE:Computer Systems and Theory
• /
• v.33 no.9
• /
• pp.634-641
• /
• 2006

Flash memory has many advantages like non-volatility and fast I/O speed, but it has also disadvantages such as not-in-place-update data and asymmetric read/write/erase speed. For the performance of flash memory storage, it is essential for the buffer replacement algorithms to reduce the number of write operations that also affects the number of erase operations. A new buffer replacement algorithm is proposed in this paper, that delays the writes of not-cold-dirty pages in the buffer cache of flash storage. We show that this algorithm effectively decreases the number of write operations and erase operations without much degradation of hit ratio. As a result overall performance of flash I/O speed is improved.

• Journal of Family Resource Management and Policy Review
• /
• v.17 no.2
• /
• pp.173-194
• /
• 2013

The purpose of this study was to examine the association between time-income availability and health-promoting behavior (physical practice, smoking, alcohol consumption) of older males (55-69). This study attempted to shed light on health-behavior changes during the transition period of male retirement. The availability of time resources was examined by addressing the amount of weekly paid labor hours. The availability of financial resources was calculated by using the debt-income ratio. The study sample comprised 1,372 (age range 55-69) male respondents of the 2006 Korean Longitudinal Study of Aging (2006 KLOSA wave 1). The results of CHAID (CHi-squared Automatic Interaction Detection) analysis uncovered four distinctive combinations of resource types: time-money poor, time rich, money rich, time-money rich. According to logit results, these four groups had different socio-demographic profiles and different health-behavior risks. The time-money poor males were unlikely to perform physical activities needed to improve their health or to quit smoking or alcohol consumption. This group was also more likely to consume alcohol compared to the time-money resource types. In contrast, the time-money rich group was more likely to exercise longer and more frequently than the reference group (time and money poor). The time-rich types, those who have time-only resources and less money, were likely to be smokers and have problems with alcohol consumption.

• Journal of the Ergonomics Society of Korea
• /
• v.25 no.4
• /
• pp.81-90
• /
• 2006

Despite the government promoting women's participation in the engineering field, some statistics show that it has yet to be achieved. Potential reasons for this phenomenon include lower level of applications by women, or inherent gender gap in the professional field. Therefore, this study attempted to find impact of gender on college admission from the Lens Model perspective and Signal Detection Theory. This study consisted of three phases: identifying the necessary cues used in the admission process, analyzing existing data, and conducting two experiments to identify the effect of gender on admission decisions. Although the college application consisted of many cues, only five cues, school ranking, GPA, SAT score, resident status, and gender, were used to capture the officers' judgment policies for engineering admissions. Two experiments were conducted to investigate the impact of the gender factor in college admission. The enrollment officers first were presented with the existing data without the gender and asked to make dichotomous judgments. Secondly, the officers were asked to perform the judgment task with the gender cue present. Results showed that the gender did not play an important role in the judgments as expected. However, ideographical analyses on judgment strategies revealed that there were significant differences between the admission officers. Possible training implications are discussed.

• Journal of Convergence for Information Technology
• /
• v.7 no.6
• /
• pp.143-151
• /
• 2017

The generalized Hough transform(GHough) can be used effectively for detecting and extracting an arbitrary-shaped 2-D model in an input image. However, the main drawbacks of the GHough are both heavy computation and an excessive storage requirement. Thus, most of the researches so far have focused on reducing both the time and space requirement of the GHough. But it is still not clear how well their improved algorithms will perform under various noise in an input image. Thus, this paper proposes a new framework that can measure the performance of the GHough quantitatively. For this purpose, we view the GHough as a detector in signal detection theory and the ROC curve will be used to specify the performance of the GHough. Finally, we show that we can evaluate the GHough under various noise conditions in an input image.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.10C
• /
• pp.942-948
• /
• 2003

In this paper, we analyze the performance of multiple trellis coded modulation applied to continuous phase frequency shift keying (MTCM/CPFSK) for the noncoherent receiver without channel state information (CSI) on the interleaved Rician fading channel. In this system, the squared cross-correlation between the received signal and a candidate signal is used as the branch metric of the Viterbi decoder. To obtain the bit error performance of this system, we analyze the approximated pairwise error probability (PEP) and the exact PEP. We also derive the equivalent normalized squared distance (ENSD) and compare it with the ENSD of the noncoherent receiver with perfect CSI. Simulation results are also provided to verify the theoretical performance analysis.

• Journal of KIISE:Computer Systems and Theory
• /
• v.30 no.10
• /
• pp.533-543
• /
• 2003

With the increase of interests in cluster, there have been a number of research efforts to address the high availability issues on cluster. However, there are no kernel-level group communication systems to support the development of kernel-level application programs and it is not easy to use traditional user-level group communication systems for the kernel-level applications. This paper presents the design and implementation issues of KCGCS(Kernel-level Cluster Group Communication System), which is a kernel-level group communication module for linux cluster. Unlike traditional user-level group communication systems, the KCGCS uses light-weight heartbeat messages and a ring-based heartbeat mechanism, which allows users to implement scalable failure detection mechanisms. Moreover, the KCGCS improves the reliability by using distributed coordinators to maintain membership information.

• Journal of Sensor Science and Technology
• /
• v.5 no.6
• /
• pp.15-24
• /
• 1996

In this study, as a part of the basic study for the application of optical fiber sensors to smart composite structures, the integrity of optical fiber sensors embedded within the composite structures was examined and then the laser signal transmitted through optical fiber sensors during the deformation of host structures was investigated. Firstly, it was found that bending test could be substituted for tensile test by comparing cumulative failure distribution based on weakest link theory and introducing the correction factor. Weibull parameters were obtained through the experiments and the correction factor was found to be applied to cumulative failure distribution derived from bending test. The integrity of embedded optical fiber sensors due to the thermal effect was evaluated by the comparison of the mean tensile strengths of cured and uncured optical fibers. Secondly, relationships between stress-strain curve obtained in tensile test of composite laminate and the intensity of laser signal transmitted through embedded optical fibers were examined and the possibility of the effective damage detection using optical fiber sensors was studied.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.2
• /
• pp.1426-1433
• /
• 2015

CCTV-applied monitoring is an effective measure to suppress potential crimes and record objective relationship; however, there is no methodology that can quantitatively compare and assess the afore-mentioned effects. Thus, this study intended to construct the methodology and analysis application that can measure the changes in the space-corresponding performance of CCTVs depending on installation measures by using 3-dimenstional virtual simulation technology. For analysis, the raster-based Isovist theory was 3-dimensionally expanded and the amount of incident sight line to each point was accumulated. At the same time, the amount of overlapped monitoring in the CCTV cameras that were connected to each measurement node was accumulated for cross-analysis. By applying the examples and analyzing the results, it was possible to construct an analysis application in use of collision detection model and quantify the changes of monitoring performance depending on positioning alternative of the cameras. Moreover, it enabled intuitive review and supplementation by reproducing visible shadow areas in a graph.

• Journal of KIISE:Computer Systems and Theory
• /
• v.31 no.12
• /
• pp.682-691
• /
• 2004

We present a novel haptic sculpting system where the user intuitively adds to and carves out material from a volumetric model using new sculpting tools in the similar way to handling real clay Haptic rendering and model deformation are implemented based on volumetric implicit surface. We enhance previous volume-based haptic sculpting systems by presenting fast and stable force computation on 3D models to be deformed. In order to bridge the gap between fast haptic process (1 KHz) and much slower visual update frequency(~30Hz), the system generates intermediate implicit surfaces between two consecutive physical models being deformed. It performs collision detection and force computation on the intermediate surface in haptic process. The volumetric model being sculpted is visualized as a geometric model which is adaptively polygonized according to the surface complexity. We also introduce various visual effects for the real-time sculpting system including mesh-based solid texturing, painting, and embossing/engraving techniques.