• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.12
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• pp.1391-1400
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• 1992

In this paper, we suggested a method for evaluating the type-I/II error which is proposed by the CCITT as a criterion for the accuracy of policing algorithms in ATM networks, By the analysis of the type-I/II error of the Leaky Bucket(LB) algorithm, we investigated the relationships between the traffic parameters and the LB parameters to police the mean and peak cell rate effectively in the ON/OFF traffic. We showed that the LB parameters, the leaky rate a and the threshold M of the LB counter, could be determined as a pair of (a, M) satisfying the type-I/II error and minimizing the response time. In the ON/OFF traffic, it has been observed that the a-M characteristic curve of the LB policing algorithm only depends on the burstiness. As the results of the performance analysis, we found that the LB algorithm exhibits a good performance in the peak rate policing, but has some problems in the mean rate policing due to the trade-off between the accuracy and the response time.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.47 no.5
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• pp.1-8
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• 2010

Recently subscribers in mobile communication services increase gradually, and the new multifunctional portable terminals can provide various functionalities. However this trend may not be desirable in Green IT respect because the emission of carbon dioxides emitted during operations of base station and mobile stations can cause significant effect on the emissions of carbon dioxides. In this paper the power saving scheme which can adjust slot index while the system is in a paging phase has been proposed and its performance has been evaluated. The slot cycle index can be adjusted according to individual user's property, its effect on the system performance has been investigated. In order to mitigate its adverse effect, power ramping scheme is considered and evaluated thereafter.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.759-765
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• 2012

This study investigates the effect of diesel combustion strategies on exhaust emissions and hydrocarbon species emissions for a 1.7 L common rail direct injection diesel engine at 1500 rpm and 3.9 bar BMEP. The first strategy is a method to adopt no EGR with a split injection composed of pilot and main injection (split injection). The second is to adopt a moderate EGR rate with main injection only (single-1). The third is to use a high level of EGR and main injection with rail pressure increase, $i.e.$ low-temperature diesel combustion (single-2). Split injection and single-1 showed a renowned phenomenon of a PM-NOx trade-off, whereas single-2 was observed of a PM-NOx trade-off to reduce PM and NOx simultaneously. HC speciation results show that the split injection produced the least amount of HC species, regardless of the carbon number bin, followed by single-1 and single-2. The ratios of methane, acetylene, and CO to THC increased as a combustion A/F ratio is richer due to reduced oxygen content in the vicinity of the combustion zone, thus enhancing pyrolysis.

• Journal of IKEEE
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• v.23 no.3
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• pp.805-810
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• 2019

We present a time-frequency analysis algorithm based on the multitaper method and the state-space frameworks. In general, time-frequency representations have a trade-off between the time duration and the spectral bandwidth by the uncertainty principle. To optimize the trade-off problems, the short-time Fourier transform and wavelet based algorithms have been developed. Alternatively, the authors proposed the state-space frameworks based on the multitaper method in the previous work. In this paper, we develop a real-time algorithm to estimate variances and spectrum using the state-space framework. We test our algorithm in spectral analysis of simulated data.

• Journal of IKEEE
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• v.27 no.4
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• pp.567-572
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• 2023

In this paper, the breakdown voltage of Pi-LDMOS (Partial isolation lateral double diffused metal oxide semiconductor) was analyzed by simulation. Breakdown voltage variation is investigated under various settings of Parial buied oxide(P-BOX) parameters(length, thickness, location) and their mechanism is specified. In addition, the change in on-resistance in the breakdown voltage and trade-off relationship was analyzed according to the change in the P-BOX parameter, and the Figure-of-merit(FOM) was calculated and compared. In proposed structure, Lbox=5 ㎛, tbox=2 ㎛, and Lbc=2 ㎛ showed the highest breakdown voltage of 138V, and Lbox=5 ㎛, tbox=1.6 ㎛, and Lbc=2 ㎛ showed the highest FOM. Compared to conventional LDMOS, the breakdown voltage is 123% and FOM is 3.89 times improved. Therefore, Pi-LDMOS has a high breakdown voltage and FOM, which can contribute to the improvement of the stable operating range of the Power IC.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.4
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• pp.31-45
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• 2023

As the Private-initiated Park Development Project (PPDP) is being actively implemented, there are concerns about the deterioration of ecosystem services due to the development of long-term unexecuted urban parks. This study aims to analyze the impact of the PPDP on the ecosystem services of urban parks by examining Central Park, which is PPDP No. 1 in Gwangju, Gyeonggi-do. A study was conducted using system thinking to comprehensively understand the changes in the ecosystem services due to the PPDP. As a result of the study, the first reason for implementing the PPDP was the local government's lack of financing. Second, it was found that the creation of urban parks through the PPDP initially deteriorated cultural services yet improved them over time, while the regulating and supporting services continued to decline. Third, trade-offs appeared between urban parks' ecosystem services (i.e.., cultural services, regulating services, and supporting services). Through this, it was confirmed that it is necessary to prepare measures for planning and managing urban parks that can reduce the trade-off between the ecosystem services of urban parks. The results of this study suggest that it is necessary to understand the relationship between environmental changes and ecosystem services over time when establishing urban park creation plans and management.

• Korea Trade Review
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• v.43 no.2
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• pp.181-204
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• 2018

This study examines the existence of a target leverage and determinants of book and market leverage. A data set of shipping firms from 2009 to 2016 was used to conduct an empirical study. The target leverage which cannot be observed in the market is estimated using a partial-adjustment model of firm capital structure. This study found that factors affecting the capital structure differ with respect to firm size, book value leverage and market value leverage. Shipping firms have a target leverage, adjust the actual leverage toward that target leverage, and consider the target leverage as an optimum leverage. The deviation of the leverage from the target leverage plays an important role to explain changes of leverage level. The greater the deviation results in greater adjustment of shipping firms toward targets. A high level of initial debt reduces leverage changes.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.721-727
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• 2002

In order to overcome trade-off among compositions, process and properties of the glasses with high PbO-base composition for PDP Rib, we studied glass crystallization and crystallization kinetics by Differential Thermal Analysis(DTA). Glass powder was obtained through melting/cooling/grinding, with 3 wt%TiO2 addition for the crystal nucleation and growth in $62PbO-19B_2O_3-10SiO_2-9(Al_2O_3-K_2O-BaO-ZnO)$(in wt%) composition glass. This powder was heat-treated for 1 to 10 h at $445^{\circ}C$ for nucleation. DTA measurements were performed to obtain the crystallization peak with $5∼25^{\circ}C/min$ heating rates. DTA crystallization peak temperature increased with increasing the heating rate and decreased with increasing the heating time. Because the Avrami parameter (n) was approximately 1, the surface crystallization occurred. The maximum nucleation time was 2 h.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.844-847
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• 2001

In this work, transient characteristics of the Non-Punch Through(NPT) Insulated Gate Bipolar Transistor(IGBT) has been studied. we has analyzed with lifetimes excess minority carrier injected into N-dirft, base region of IGBT's BJT part and accumulated charge of on-state which affected swiching characteristic. In this paper, excess minority carrier and charge distribution in active base region is expressed analytically. This analysis proposed optical trade-off between lifetimes and accumulated charge for decreasing switching losses because charge result in switching loss when device was tuned off.

• Journal of KIISE:Computing Practices and Letters
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• v.13 no.4
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• pp.231-239
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• 2007

This paper presents the trade-off relationship between area and performance in the hardware design space exploration for the Korean national standard 128-bit block cipher algorithm SEED. In this paper, we compare the following four hardware design types of SEED algorithm : (1) Design 1 that is 16 round fully pipelining approach, (2) Design 2 that is a one round looping approach, (3) Design 3 that is a G function sharing and looping approach, and (4) Design 4 that is one round with internal 3 stage pipelining approach. The Design 1, Design 2, and Design 3 are the existing design approaches while the Design 4 is the newly proposed design in this paper. Our new design employs the pipeline between three G-functions and adders consisting of a F function, which results in the less area requirement than Design 2 and achieves the higher performance than Design 2 and Design 3 due to pipelining and module sharing techniques. We design and implement all the comparing four approaches with real hardware targeting FPGA for the purpose of exact performance and area analysis. The experimental results show that Design 4 has the highest performance except Design 1 which pursues very aggressive parallelism at the expanse of area. Our proposed design (Design 4) shows the best throughput/area ratio among all the alternatives by 2.8 times. Therefore, our new design for SEED is the most efficient design comparing with the existing designs.