• Journal of Communications and Networks
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• v.8 no.1
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• pp.70-84
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• 2006

We propose a new distributed QoS routing scheme called pre-computation based selective probing (PCSP). The PCSP scheme is designed to provide an exact solution to the constrained optimization problem with moderate overhead, considering the practical environment where the state information available for the routing decision is not exact. It does not limit the number of probe messages, instead, employs a qualitative (or conditional) selective probing approach. It considers both the cost and QoS metrics of the least-cost and the best-QoS paths to calculate the end-to-end cost of the found feasible paths and find QoS-satisfying least-cost paths. It defines strict probing condition that excludes not only the non-feasible paths but also the non-optimal paths. It additionally pre-computes the QoS variation taking into account the impreciseness of the state information and applies two modified QoS-satisfying conditions to the selection rules. This strict probing condition and carefully designed probing approaches enable to strictly limit the set of neighbor nodes involved in the probing process, thereby reducing the message overhead without sacrificing the optimal properties. However, the PCSP scheme may suffer from high message overhead due to its conservative search process in the worst case. In order to bound such message overhead, we extend the PCSP algorithm by applying additional quantitative heuristics. Computer simulations reveal that the PCSP scheme reduces message overhead and possesses ideal success ratio with guaranteed optimal search. In addition, the quantitative extensions of the PCSP scheme turn out to bound the worst-case message overhead with slight performance degradation.

• Nuclear Medicine and Molecular Imaging
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• v.42 no.2
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• pp.98-111
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• 2008

This review introduces advances in clinical and pre-clinical single photon emission computed tomography (SPECT) and positron emission tomography (PET) providing noninvasive functional images of biological processes. Development of new collimation techniques such as multi-pinhole and slit-slat collimators permits the improvement of system spatial resolution and sensitivity of SPECT. Application specific SPECT systems using smaller and compact solid-state detector have been customized for myocardial perfusion imaging with higher performance. Combined SPECT/CT providing improved diagnostic and functional capabilities has been introduced. Advances in PET and CT instrumentation have been incorporated in the PET/CT design that provide the metabolic information from PET superimposed on the anatomic information from CT. Improvements in the sensitivity of PET have achieved by the fully 3D acquisition with no septa and the extension of axial field-of-view. With the development of faster scintillation crystals and electronics, time-of-flight (TOF) PET is now commercially available allowing the increase in the signal-to-noise ratio by incorporation of TOF information into the PET reconstruction process. Hybrid PET/SPECT/CT systems has become commercially available for molecular imaging in small animal models. The pre-clinical systems have improved spatial resolution using depth-of-interaction measurement and new collimators. The recent works on solid state detector and dual modality nuclear medicine instrumentations incorporating MRI and optical imagers will also be discussed.

• Journal of the Korean Geotechnical Society
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• v.36 no.9
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• pp.33-44
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• 2020

In order to analyze the shear strength characteristics of the grout with sudden gelation in the pre-hardening state, the viscosity of the mixture and the indoor vane shear test were performed. The grout was prepared according to the water-cement (w/c) ratio and the shear strength test was conducted. The plastic-state shear strength of grout was affected by the w/c ratio, so the lower the w/c ratio, the higher the initial shear strength was, and the longer the curing time was, the higher the shear strength was. The maximum shear strength occurred at the faster rotation angle as the higher shear strength was developed, and the lower shear strength occurred at the larger rotation angle. In addition, it was confirmed that the pre-hardening grout rapidly decreased in strength after the maximum shear strength was gained, and converged at a certain level after the rotation angle of the vane blade was about 70° to 90°.

• Korea-Australia Rheology Journal
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• v.17 no.3
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• pp.125-130
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• 2005

Coalescence process of binary immiscible fluid mixtures having bimodal size distributions, prepared by mixing two pre-sheared samples at different shear rates, ${\gamma}_{pre1}\;and\;{\gamma}_{pre2}$, under shear flow at a final shear rate, ${\gamma}_f$, are examined by transient shear stress measurements and microscopic observations in comparison with the results for simply pre-sheared samples having narrow size distributions (unimodal distribution samples). Component fluids are a silicone oil (PDMS) and a hydrocarbon-formaldehyde resin (Genelite) and their viscosities are 14.1 and 21.0 $pa{\cdot}sec$ at room temperature $(ca.\;20^{\circ}C)$, respectively. The weight ratio of PDMS: Genelite was 7:3. Three cases, $({\gamma}_{pre1}=7.2sec^{-1},\;{\gamma}_{pre2}=12.0sec^{-1}\;and\;{\gamma}_f=2.4sec^{-1}),\;({\gamma}_{pre1}=0.8sec^{-1},\;{\gamma}_{pre2}=4.0sec^{-1}\;and\;{\gamma}_f=2.4sec^{-1}),\;and\;({\gamma}_{pre1}=7.2sec^{-1},\;{\gamma}_{pre2}=12.0^sec^{-1}\;and\;{\gamma}_f=7.2sec^{-1})$ the first case, transient shear stress did not show any significant difference but domains larger than the initial state are observed at short times. In the latter cases, there exist undershoot of shear stress, reflecting existence of deformed large domains, which is confirmed by the direct observation. It is concluded that coalescence between large and small domains more frequently occur than coalescence between the domains with similar size in the bimodal distribution samples.

• The Journal of Korean Academic Society of Nursing Education
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• v.9 no.1
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• pp.115-125
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• 2003

This study was conducted to investigate whether a computer information offered in advance of the test would decrease anxiety degree in coronary angiogram subjects. The study design was a nonequivalent control group, none-synchronized design. The subjects of study were 53 patients who were admitted at C hospital in K city for coronary angiogram. The 53 subjects were assigned to experimental(25) and control(28) groups. The computer information set up by researcher was used as the experimental treatment and 10 minutes long. Spielberger's state anxiety scale translated by Kim and Shin(1978) and sphygmomanometer were used for data collection. The data were collected from July 1, 2000 to March 31, 2001, and analyzed by chi-square, paried t-test, t-test, ANCOVA, and Pearson's Correlation Coefficients using SPSS/PC+. The results of this study were summarized as follows : 1. The first hypothesis that 'post-test state anxiety score will be lower than pre-test state anxiety score in experimental group' was supported(t=2.40, p=.020). 2. The second hypothesis that 'post-test systole will be lower than pre-test systole in experimental group' was not supported(t=-.30, p=.765). 3. The third hypothesis that 'post-test Diastole will be lower than pre-test diastole in experimental group' was not supported'(t=-1.42, p=.161). 4. The fifth hypothesis that 'the experimental group who is given the computer information will be lower in state anxiety score than the control group who is not given the computer information' was supported(F=9.17, p=.004). 5. The sixth hypothesis that 'the experimental group who is given the computer information will be lower in systole than the control group who is not given the computer information' was supported (F=7.16, p=.010). 6. The seventh hypothesis that 'the experimental group who is given the computer information will be lower in diastole than the control group who is not given the computer information' was not supported'(F=.55, p=.462). 7. The eleventh hypothesis that 'the lower the post-test state anxiety, the lower the uneasiness score during the test' was not supported(r=-.013, p=.926). 8. The eighth hypothesis that 'the lower the post-test state anxiety, the lower the nervousness score during the test' was supported(r=.326, p=.017).

• Korean Journal of Psychosomatic Medicine
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• v.6 no.2
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• pp.147-154
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• 1998

Objective : This study was designed to find the characteristics of MMPI that could influence the outcome of cognitive behavioral therapy(CBT) for panic disorder. Methods : 34 patients who met DSM-IV criteria for panic disorder with or without agoraphobia had completed 11 weekly sessions of cognitive behavioral therapy. All the patients were assessed with MMPI before the initiation of treatment. Five self-report measures including Beck Depression Inventory(BDI), Spielberger State-Trait Anxiety Inventory(STAI), Agoraphobic Cognition Questionnarie(ACQ), Body Sensation Questionnaire(BSQ), and Daily Anxiety Selfrating (0 - 8 scales) were also assessed as a pre- and post-treatment assessment. After the completion of treatment, patients were classified by the High End-State(HES) functioning group and the Low End-State(LES) functioning group for the data analysis. Results : 1) The LES group showed significantly higher scores in Hypochondriasis Scale(HS), Depression Scale(D), Hysterical Scale(Hy), Obsessive Scale(Pt), Schizophrenia Scale(Sc) and Validity Scale(F) of MMPI than the HES group. However, these differences gave impressions that the LES group had more severe symptoms rather than that they could be the factors influencing the outcome of CBT. 2) Though, the severity of symptoms of the LES group in the 5 measures of pre-assessment was basically higher than that of the HES group. The fact that both group showed the similar improvement between pre- and post-assessment supported the above interpretation. Conclusion : In regarding the above results, MMPI was not a proper tool that could provide the factors influencing the outcome of CBT. In the future study, the authors need to use a different tool that can find the personality characteristics more directly.

• Journal of Korean Elementary Science Education
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• v.27 no.4
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• pp.371-384
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• 2008

The purposes of this study were to investigate perspective teachers' conceptions of liquid-state and get implications for the direction of science curriculum or professional development. The instrument was composed of seven questions focusing on aspects of liquid-state phenomena. The results showed that the participants have various alternative concepts about liquid-state. The problem revealed in almost every question was their macroscopic explanations for the phenomena. In addition, it appeared that the participants seemed to understand phenomena in terminology level, but they didn't know basic reasons or fundamental concepts about the phenomena. It is required to change the curriculum or instructional methods in secondary school and teacher education programs to anchor the scientific concepts on molecular or microscopic level.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.12
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• pp.1829-1836
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• 2010

The district heating system distributes the heat generated from a cogeneration plant to wider locations. In this process, the district heating pipe (DHP) is subjected to internal and external loadings. The internal loadings are generally caused by the operating conditions such as water temperature and internal pressure. Frictional interactions between the pipes and the soil contribute to the external loadings. Thus, investigation of the mechanisms of failure of DHPs will help to guarantee both mechanical stability and heating efficiency. In this study, we investigate the local buckling of DHPs using limit state design (LSD). Two methods are considered: the use of the limit state for the width-thickness ratio and the use of the limit state for the strain. The results are used to confirm that the DHP is stable under local buckling. Finally, we suggest a minimum preheating temperature for avoiding local buckling.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.6
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• pp.1085-1094
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• 1994

We propose a traffic flow control scheme of B-NT with temporary cell buffering and selective cell discarding to prevent congestion state of the network nodes in B-ISDN systems to reduce or suppress output cell strams towards T interface. We define the states of the network nodes as normal, pre-congestion, and congestion. In a pre-congestion state, the loss-sensitive traffic is temporarily buffered to slow down the rate of the output traffic streams. In a congestion state, the delay-sensitive traffic is selectively discarded to suppress the output traffic streams as possible in addition to the cell buffering. We model the input cell streams and the states of the network nodes with Interrupted Bernoulli Process and 3-state Markov chain to analyze the performance of the proposed scheme in the B-NT system. The appropriate size of the cell buffer is explored by means of simulation and the influence on the performance of the proposed scheme by the network node state is discussed. As results, more than 2,00 cells of buffer size is needed for the control of medium of lower than the medium, degree of congestion occurrence in the network node while the control of high degree of congestion occurrence is nearly impossible.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4552-4567
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• 2014

A (n,t,n) secret sharing scheme is to share a secret among n group members, where each member also plays a role of a dealer,and any t shares can be used to recover the secret. In this paper, we propose a strong (k,t,n) verifiable multi-secret sharing scheme, where any k out of n participants operate as dealers. The scheme realizes both threshold structure and adversary structure simultaneously, and removes a trusted third party. The secret reconstruction phase is performed using an additive homomorphism for decreasing the storage cost. Meanwhile, the scheme achieves the pre-verification property in the sense that any participant doesn't need to reveal any information about real master shares in the verification phase. We compare our proposal with the previous (n,t,n) secret sharing schemes from the perspectives of what kinds of access structures they achieve, what kinds of functionalities they support and whether heavy storage cost for secret share is required. Then it shows that our scheme takes the following advantages: (a) realizing the adversary structure, (b) allowing any k out of n participants to operate as dealers, (c) small sized secret share. Moreover, our proposed scheme is a favorable candidate to be used in many applications, such as secure multi-party computation and privacy preserving data mining, etc.