• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 하계종합학술대회 논문집(2)
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• pp.165-168
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• 2002

As the demand for higher data-rate chip-to-chip communication such as memory-to-controller, processor-to-processor increases, low cost high-speed serial links\ulcorner become more attractive. This paper describes a 0.25-fm CMOS 1.6Gbps/pin 4-level transceiver using Stub Series Terminated Logic for high Bandwidth. For multi-gigabit/second application, the data rate is limited by Inter-Symbol Interference (ISI) caused by channel low pass effects, process-limited on-chip clock frequency, and serial link distance. The proposed transceiver uses multi-level signaling (4-level Pulse Amplitude Modulation) using push-pull type, double data rate and flash sampling. To reduce Process-Voltage-Temperature Variation and ISI including data dependency skew, the proposed high-speed calibration circuits with voltage swing controller, data linearity controller and slew rate controller maintains desirable output waveform and makes less sensitive output. In order to detect successfully the transmitted 1.6Gbps/pin 4-level data, the receiver is designed as simultaneous type with a kick - back noise-isolated reference voltage line structure and a 3-stage Gate-Isolated sense amplifier. The transceiver, which was fabricated using a 0.25 fm CMOS process, performs data rate of 1.6 ~ 2.0 Gbps/pin with a 400MHB internal clock, Stub Series Terminated Logic ever in 2.25 ~ 2.75V supply voltage. and occupied 500 * 6001m of area.

• Bioinformatics and Biosystems
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• 제2권1호
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• pp.28-32
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• 2007

The protein phosphorylation is one of the important processes in the cell signaling pathway. A variety of protein kinase families are involved in this process, and each kinase family phosphorylates different kinds of substrate proteins. Many methods to predict the kinase-specific phosphoryrated sites or different types of phosphorylated residues (Serine/Threonine or Tyrosin) have been developed. We employed Supprot Vector Machine (SVM) to attempt the prediction of protein kinase specific phosphorylation sites. 10 different kinds of protein kinase families (PKA, PKC, CK2, CDK, CaM-KII, PKB, MAPK, EGFR) were considered in this study. We defined 9 residues around a phosphorylated residue as a deterministic instance from which protein kinases determine whether they act on. The subsets of PSI-BALST profile was converted to the numerical vectors to represent positive or negative instances. When SVM training, We took advantage of multiple SVMs because of the unbalanced training sets. Representative negative instances were drawn multiple times, and generated new traing sets with the same positive instances in the original traing set. When testing, the final decisions were made by the votes of those multiple SVMs. Generally, RBF kernel was used for the SVMs, and several parameters such as gamma and cost factor were tested. Our approach achieved more than 90% specificity throughout the protein kinase families, while the sensitivities recorded 60% on average.

• 경영과학
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• 제26권3호
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• pp.23-35
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• 2009

This study deals with the location management in WCDMA (Wideband Code Division Multiple Access) networks. The new location management method is the one of the many techniques used to provide the packet switched (PS) services effectively in WCDMA networks. WCDMA introduces RA (routing area) for the PS services in addition to LA (location area) for the circuit switched (CS) services. WCDMA system also adopts the cooperative paging and the combined area update which are to decrease signaling traffic using the PS network resources for the CS services. Considering the characteristics of the WCDMA networks, this study formulate into the mathematical programming problem for the location management. Rather than the existing researches which consider the single MSC/SGSN networks, we deal with the multi MSC/SGSN networks, where both MSC area and SGSN area should be determined as well. Fairness between traffic loads of MSC/SGSN and the system cost incurred to MSC/SGSN are also incorporated into our model, which make the model more realistic. We propose greedy algorithms for the problems, which consists of the merger of two neighboring areas and the movement of an area. Extensive experiment has been done based on the realistic problem examples. Followed by the analysis of parameter effect on the final solutions and the quality of final solutions obtained by our greedy algorithms. Our proposed model and analysis result can be used to determine WCDMA system areas and to predict the system performance measures by the determination.

• Journal of Information Processing Systems
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• 제14권3호
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• pp.771-789
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• 2018

In heterogeneous wireless networks supporting multi-access services, selecting the best network from among the possible heterogeneous connections and providing seamless service during handover for a higher Quality of Services (QoSs) is a big challenge. Thus, we need an intelligent vertical handover (VHO) decision using suitable network parameters. In the conventional VHOs, various network parameters (i.e., signal strength, bandwidth, dropping probability, monetary cost of service, and power consumption) have been used to measure network status and select the preferred network. Because of various parameter features defined in each wireless/mobile network, the parameter conversion between different networks is required for a handover decision. Therefore, the handover process is highly complex and the selection of parameters is always an issue. In this paper, we present how to maximize network utilization as more than one target network exists during VHO. Also, we show how network parameters can be imbedded into IEEE 802.21-based signaling procedures to provide seamless connectivity during a handover. The network simulation showed that QoS-effective target network selection could be achieved by choosing the suitable parameters from Layers 1 and 2 in each candidate network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권8호
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• pp.3904-3917
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• 2017

IP multimedia subsystem (IMS) is an open standardized architecture for delivering multimedia service over IP network in a route-agnostic manner. With the increasing popularity of conversational class service, the delivery of a traffic flow with a certain bandwidth demand over a single network path is either not possible or not cost-effective. Multipath transmission is considered to be a promising solution to provide high-quality delivery service. This paper proposes a software defined service overlay network (SDSON) based multipath transmission framework for IMS, which is complementary to existing network architecture. The framework transforms original two-party session negotiation into three-party session negotiation that supports participants to negotiate multipath transmission capacity and path information by signaling message. Based on existing IETF standards, SIP and SDP are scalable to support these functions. Finally, the proposed framework is fully implemented on open source platform and examined by experiments. Experimental results show that multipath-enabled IMS is an effective way to improve the delivery performance of conversational class service.

• Journal of Information Processing Systems
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• 제13권5호
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• pp.1410-1429
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• 2017

Mobility arises naturally in the Internet of Things networks, since the location of mobile objects, e.g., mobile agents, mobile software, mobile things, or users with wireless hardware, changes as they move. Tracking their current location is essential to mobile computing. To overcome the scalability problem, hierarchical architectures of location databases have been proposed. When location updates and lookups for mobile objects are localized, these architectures become effective. However, the network signaling costs and the execution number of database operations increase particularly when the scale of the architectures and the numbers of databases becomes large to accommodate a great number of objects. This disadvantage can be alleviated by a location caching scheme which exploits the spatial and temporal locality in location lookup. In this paper, we propose a hierarchical location caching scheme, which acclimates the existing location caching scheme to a hierarchical architecture of location databases. The performance analysis indicates that the adjustment of such thresholds has an impact on cost reduction in the proposed scheme.

• The Journal of Asian Finance, Economics and Business
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• 제8권5호
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• pp.551-559
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• 2021

The maturity structure of corporate debt is one of the significant financing choices that a firm must make simultaneously while deciding how to finance its operational and investment decisions. Even though the capital structure is one of the scrutinized topics of interest in the corporate finance literature, scarce studies have investigated corporate debt maturity, even less so in the context of emerging markets. The choice of a suitable debt maturity structure is exceptionally relevant for firms. It can enable them to avoid mismatch by aligning assets in line with liabilities, addressing agency-related problems, sidestep the ill effects of cost of capital, and signaling the firms' earning quality and value. The study investigates the firm-specific and macroeconomic determinants significant for the debt maturity structure of Vietnamese corporate firms. A sample of 722 non-financial firms listed on the Ho Chi Minh and Hanoi Stock Exchange in Vietnam from 2007 to 2018 was taken to test the hypothesis. The study's methods fixed effects panel data analysis provides empirical evidence that firm size, firms' quality, liquidity, leverage, asset maturity, tax impact, and macro variables are significantly related to the debt maturity structure.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권1호
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• pp.185-201
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• 2023

Grant-free random access (GFRA) can reduce the access delay and signaling cost, and satisfy the short transmission packet and strict delay constraints requirement in internet of things (IoT). IoT is a major trend in the future, which is characterized by the variety of applications and devices. However, most existing studies on GFRA only consider a single type of device and omit the effect of access delay. In this paper, we study GFRA in multicell massive multipleinput multiple-output (MIMO) systems where different types of devices with various configurations and requirements co-exist. By introducing the backoff mechanism, each device is randomly activated according to the backoff parameter, and active devices randomly select an orthogonal pilot sequence from a predefined pilot pool. An analytical approximation of the average spectral efficiency for each type of device is derived. Based on it, we obtain the optimal backoff parameter for each type of devices under their delay constraints. It is found that the optimal backoff parameters are closely related to the device number and delay constraint. In general, devices that have larger quantity should have more backoff time before they are allowed to access. However, as the delay constraint become stricter, the required backoff time reduces gradually, and the device with larger quantity may have less backoff time than that with smaller quantity when its delay constraint is extremely strict. When the pilot length is short, the effect of delay constraints mentioned above works more obviously.

• 한국동물생명공학회지
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• 제38권3호
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• pp.121-130
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• 2023

Background: Coating a culture plate with molecules that aid in cell adhesion is a technique widely used to produce animal cell cultures. Extracellular matrix (ECM) is known for its efficiency in promoting adhesion, survival, and proliferation of adherent cells. Gelatin, a cost-effective type of ECM, is widely used in animal cell cultures including feeder-free embryonic stem (ES) cells. However, the optimal concentration of gelatin is a point of debate among researchers, with no studies having established the optimal gelatin concentration. Methods: In this study, we coated plastic plates with gelatin in a concentration-dependent manner and assessed Young's modulus using atomic force microscopy (AFM) to investigate the microstructure of the surface of each plastic plate. The adhesion, proliferation, and differentiation of the ESCs were compared and analyzed revealing differences in surface microstructure dependent on coating concentration. Results: According to AFM analysis, there was a clear difference in the microstructure of the surface according to the presence or absence of the gelatin coating, and it was confirmed that there was no difference at a concentration of 0.5% or more. ES cell also confirmed the difference in cell adhesion, proliferation, and differentiation according to the presence or absence of gelatin coating, and also it showed no difference over the concentration of 0.5%. Conclusions: The optimum gelatin-coating for the maintenance and differentiation of ES cells is 0.5%, and the gelatin concentration-mediated microenvironment and ES cell signaling are closely correlated.

• 재무관리연구
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• 제24권4호
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• pp.135-161
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• 2007

본 연구는 1997년 1월 1일부터 2006년 12월 31일까지 한국증권선물거래소의 유가증권시장과 코스닥시장에 상장된 IPO 기업을 대상으로 배당개시결정의 3가지 측면, 즉, 배당개시 여부, 배당수준 및 배당개시시점의 결정요인을 실증분석 하였으며, 주요한 분석결과는 다음과 같다. 첫째, 주요 배당이론, 즉, 잔여배당이론, 배당신호이론, 대리인이론, 케이터링이론, 거래비용이론 등에서 제시된 배당결정요인들은 IPO 기업의 배당개시결정에도 유의한 영향을 미친다. 성장기회 변수인 M/B 비율과 R&D지출 비율이 낮을수록, 수익성 변수인 EBITDA 비율이 높을수록, 거래량회전율이 낮을수록, 그리고 배당프리미엄이 높을수록 배당개시확률은 높아진다. 둘째, 주요 배당이론에서 제시된 배당결정요인 중에서 성장기회 변수와 수익성 변수는 IPO 기업의 배당수준결정에도 유의한 영향을 미친다. 즉, 성장기회 변수인 R&D지출 비율이 낮을수록, 그리고 수익성 변수인 EBITDA 비율이 높을수록 배당수준이 증가한다. 셋째, 배당개시확률을 증가시키는 요인들은 배당개시시점을 단축시키는 요인으로 작용한다. 즉, 성장기회 변수인 R&D지출이 낮을수록, 수익성 변수인 EBITDA 비율이 높을수록, 그리고 거래량 회전율이 낮을수록, 배당개시확률은 증가하고 배당개시시점은 단축된다. 특히, 수익성 변수인 EBITDA 비율 및 거래량회전율은 배당개시시점과 배당지급/연기 결정에 모두 유의한 영향을 미친다. 즉, EBITDA 비율이 높을수록 배당개시시점이 단축되고, 거래량회전율이 높을수록 배당개시시점이 연기된다. 또한 배당개시기업의 대부분은 IPO 후 2년 이내에 배당개시 여부를 결정한다. 따라서 기업이 IPO 후 2년 이내에 배당개시를 하지 않으면 그 이후에는 배당개시를 하지 않을 가능성이 많다.