• The Transactions of the Korea Information Processing Society
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• v.4 no.7
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• pp.1770-1780
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• 1997

Our problem is improvement of image quality because it is inevitable cell loss of image data when traffic congestion occurs. If cells are discarded indiscriminately in transmission of MPEG video data, it occurs severe degradation in quality of service(QOS). In this paper, to solve this problem, we propose two method. The first, we analyze the traffic characteristics of an MPEG encoder and generate high priority and low priority data stream. During network congestion, only the least low priority cells are dropped, and this ensures that the high priority cells are successfully transmitted, which, in turn, guarantees satisfactory QoS. In this case, the prioritization scheme for the encoder assigns components of the data stream to each priority level based on the value of a parameter ${\beta}$. The second, Number of high priority cells are increased when value of ${\beta}$ is large. It occurs the loss of high priority cell in the congestion. To prevent it, this paper is regulated to data stream rate as buffer occupancy with UPC controller. Therefore, encoder's bandwidth can be calculated renegotiation of the encoder and networks. In this paper, the encoder's bandwidth requirements are characterized by a usage parameter control (UPC) set consisting of peak rate, burstness, and sustained rate. An adaptive encoder rate control algorithm at the Networks Interface Card(NIC) computes the necessary UPC parameter to maintain the user specified quality of service. Simulation results are given for a rate-controlled VBR video encoder operating through an ATM network interface which supports dynamic UPC. These results show that dynamic bandwidth renegotiation of prioritized data stream could provided bandwidth saving and significant quality gains which guarantee high priority data stream.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.2 no.2
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• pp.3-8
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• 2009

The traction system has been mainly used for rehabilitation and correction of patients with spine or gait diseases in orthopedics or at home. Some problems could occur in human body when patients forced their training using the traction system. So it needs to measure a traction force and control the training time. However, most of products on market have no sensor measuring traction force. Thus we designed and made a sensor detecting traction force using strain gauge, amplifier for transition to output signal and experiment devices for performance test. We carried out experiment of a sensor detecting a traction force and measured electric responses of it with respect to traction loads. Maximum error was within about 1% for experiments in static condition and the average error was about 0.7% for experiments in dynamic condition. We concluded that it is possible to use the developed sensor for measurement of traction force since the maximum output variation of a sensor detecting a traction force was about 0.3% in $0^{\circ}C-60^{\circ}C$ temperature condition.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.5
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• pp.514-520
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• 2018

Presence service provides various information about users such as locations, status of on/offline and network access methods, and number of presence resources required by each users increases largely in mobile environment. Therefore an effective method which can reduce load of presence servers is needed. In this paper, a large scale distributed presence service system which can distribute effectively total presence system load of presence servers using message control session has been presented. This large scale distributed presence service system provides various presence information for massive volumes of users. In this study, a new message control session architecture which can dynamically distribute loads of the presence servers to multiple servers has been presented, and a new presence information data architecture for controlling load of the presence servers has been designed. In this architecture, each presence server can exchange current load level in real time to get variance of the total system load change according to user numbers, and can distribute system load to maintain load level of each server evenly. The performance of the proposed large scale distributed presence service system has been analysed by experiments. The results has been showed that average presence resource subscription processing time reduced from 42.6% to 73.6%, and average presence notification processing time reduced from 37.6% to 64.8%.

• Journal of KIISE:Databases
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• v.31 no.3
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• pp.261-273
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• 2004

Advances in information and communication technologies have been creating new classes of applications in the area of databases. For example, in moving object databases, which track positions of a lot of objects, or stream databases, which process data streams from a lot of sensors, data Processed in such database systems are usually changed very rapidly and continuously. However, traditional database systems have a problem in processing these rapidly and continuously changing data because they suppose that a data item stored in the database remains constant until It is explicitly modified. The problem becomes more serious in the R-tree, which is a typical index structure for multidimensional data, because modifying data in the R-tree can generate cascading node splits or merges. To process frequent updates more efficiently, we propose a novel update technique for the R-tree, which we call the leaf-update technique. If a new value of a data item lies within the leaf MBR that the data item belongs, the leaf-update technique changes the leaf node only, not whole of the tree. Using this leaf-update manner and the leaf-access hash table for direct access to leaf nodes, the proposed technique can reduce update cost greatly. In addition, the leaf-update technique can be adopted in diverse variants of the R-tree and various applications that use the R-tree since it is based on the R-tree and it guarantees the correctness of the R-tree. In this paper, we prove the effectiveness of the leaf-update techniques theoretically and present experimental results that show that our technique outperforms traditional one.

• Korean Journal of Optics and Photonics
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• v.9 no.5
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• pp.333-341
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• 1998

The novel integrated device, 1.55 ${\mu}{\textrm}{m}$ DR-LD(distrbuted reflector laser diode) integrated EA-MOD (electro-absorption modulator) as light source, is proposed to improve the device yield and its operational performances. This device can be easily fabricated by the selective MOVPE technique and its fabrication processes are almost the same as the reported 1.55 ${\mu}{\textrm}{m}$ DFB-LD(distributed feedback laser diode) integrated EA-MOD except the asymmetric gratings. The static and dynamic properties are investigated simultaneously by solving the transfer matrix method for light propagation, the time-dependent rate equation for carrier change and schr$\"{o}$dinger equation for QCSE (Quantum-Confined Stark Effect). The performances of the proposed device such as output power, chirp, and extinction ratio are compared with those of DFB-LD integrated EA-MOD. Under 10Gb/s NRZ modulation, we obtain that DR-LD integrated EA-MOD. is 30% higher in output power on the on-state, about 50% lower in chirp, and slightly larger in extinction ratio than DFB-LD integrated EA-MOD.-MOD.

• Journal of Korean Society of Transportation
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• v.27 no.5
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• pp.209-221
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• 2009

Travel time estimation under given traffic conditions is important for providing drivers with travel time prediction information. But the present expressway travel time estimation process cannot calculate a reliable travel time. The objective of this study is to estimate the path travel time spent in a through lane between origin tollgates and destination tollgates on an expressway as a prerequisite result to offer reliable prediction information. Useful and abundant toll collection system (TCS) data were used. When estimating the path travel time, the path travel time is estimated combining the link travel time obtained through a preprocessing process. In the case of a lack of TCS data, the TCS travel time for previous intervals is referenced using the linear interpolation method after analyzing the increase pattern for the travel time. When the TCS data are absent over a long-term period, the dynamic travel time using the VDS time space diagram is estimated. The travel time estimated by the model proposed can be validated statistically when compared to the travel time obtained from vehicles traveling the path directly. The results show that the proposed model can be utilized for estimating a reliable travel time for a long-distance path in which there are a variaty of travel times from the same departure time, the intervals are large and the change in the representative travel time is irregular for a short period.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.452-452
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• 2010

차세대 디스플레이로서 주목 받고 있는 유연성 정보표시 소자 개발에 대한 요구도가 날로 증대되고 있다. 유연성 정보표시 소자로서 플라스틱 기반 유연성 소자가 특히 주목 받고 있으나, 이의 실용화를 위해서는 플라스틱 기판에 적용 가능한 보호막 형성 기술 개발이 선행되어야 한다. 플라스틱 필름의 경우 높은 산소 및 수분 투과율 때문에 유연성 디스플레이의 응용에 걸림돌이 되고 있다. 플라스틱 기반 유연성 소자의 장수명화를 위해서는 수분과 산소의 투과를 방지하는 passivation layer 형성 기술이 필수적으로 요구된다. 본 연구에서는, polyethylene terephethalate (PET) 기판상에 증착된 $SiO_x$ 보호막의 합성에 있어서 중간층 유무에 따른 투습특성의 변화를 살펴보았다. 기화된 HMDSO (Hexamethyldisiloxane)와 Ar 및 $O_2$ 혼합기체를 이용하여 PECVD 방법으로 $SiO_x$ 박막을 합성하였다. 15 nm 두께의 $Al_2O_3$를 중간층으로 사용하여 중간층 유무에 따른 초기성장 거동 변화가 $SiO_x$ 박막의 투습 특성에 미치는 영향을 조사하였다. $SiO_x$ 박막 구조와 화학적 조성은 각각 FE-SEM과 FT-IR을 이용하여 분석하였으며, AFM을 이용하여 $SiO_x$ 박막 표면 미세 형상을 관찰하였다. 투습률은 MOCON사(社)의 Permatran-W 3/33 MA을 이용하여 측정하였다. 그리고 반복 굽힘 시험기를 이용하여 $SiO_x$ 보호막의 동적 투습 특성을 조사하였다. $Al_2O_3$ 중간층 유무에 따라 $SiO_x$ 박막의 투습률 (WVTR; water vapor transmission rate)은 ${\sim}10^{-1}g/m^2/day$(300 nm-thick $SiO_x$/PET)에서 ${\sim}5{\times}10^{-3}g/m^2/day$(300 nm-thick $SiO_x$/15 nm-thick $Al_2O_3$/PET)으로 변화하였다. 300 nm-thick $SiO_x$/15 nm-thick $Al_2O_3$/PET 시편의 경우 곡지름 50 mm에서 1,000회 반복 굽힘 후에도 투습률 변화를 보이지 않았다. 이와 같은 $SiO_x$ 박막의 투습 특성 변화는 $Al_2O_3$ 중간층 유무에 따른 초기 성장 거동의 변화로 해석된다. FE-SEM 및 AFM 표면 미세 구조 관찰을 통한 초기 성장 거동 변화 조사 결과, $Al_2O_3$ 중간층 없이 PET 기판위에 $SiO_x$ 박막 증착한 경우 3 차원 성장을 하는 반면, PET기판위에 $Al_2O_3$ 중간층 형성 후 $SiO_x$ 박막 증착하는 경우 2 차원 성장을 하게 됨을 관찰하였다. 따라서 본 연구를 통하여, 플라스틱 기반 유연성 표시 소자에 적용하기 위한 $SiO_x$ 보호막 합성 에 있어서 초기 성장 거동의 변화가 투습 특성에 민감한 영향을 미침을 알 수 있었다.

• Journal of Korea Water Resources Association
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• v.39 no.3 s.164
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• pp.187-198
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• 2006

Korea Water Resources Corporation(KOWACO) has developed the Integrated Real-time Water Management System(IRWMS) that calculates monthly optimal ending target storages by using Sampling Stochastic Dynamic Programming(SSDP) with Ensemble Streamflow Prediction(ESP) running on the $1^{st}$ day of each month. This system, however, has a shortcoming: it cannot reflect the hydrolmeteorologic variations in the middle of the month. To overcome this drawback, in this study updated ESP forecasts three times each month by using the observed precipitation series from the $1^{st}$ day of the month to the forecast day and the historical precipitation ensemble for the remaining days. The improved accuracy and its effect on the reservoir operations were quantified as a result. SSDP/ESP21 that reflects within-a-month hydrolmeteorologic states saves $1\;X\;10^6\;m^3$ in water shortage on average than SSDP/ESP01. In addition, the simulation result demonstrated that the effect of ESP accuracy on the reduction of water shortage became more important when the total runoff was low during the drawdown period.

• Korean Journal of Microbiology
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• v.54 no.3
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• pp.188-199
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• 2018

Genomic epidemiology exploits various basic microbial research areas. High-throughput sequencing technologies dramatically have been expanding the number of microbial genome sequences available. Abundant genomic data provide an opportunity to perform strain typing more effectively, helping identify microbial species and strains at a higher resolution than ever before. Genomic epidemiology needs to find antimicrobial resistance genes in addition to standard genome annotations. Strain typing and antimicrobial resistance gene finding are static aspects of genomic epidemiology. Finding which hosts infected which other hosts requires the inference of transient transmission routes among infected hosts. The strain typing, antimicrobial resistance gene finding, and transmission tree inference would allow for better surveillance of microbial infectious diseases, which is one of the ultimate goals of genomic epidemiology. Among several high-throughput sequencing technologies, genomic epidemiology will benefit from the more portability and shorter sequencing time of the Oxford Nanopore Technologies's MinION, the third-generation sequencing technology. Here, this study reviewed computational methods for quantifying antimicrobial resistance genes and inferring disease transmission trees. In addition, the MinION's applications to genomic epidemiology were discussed.

• Applied Chemistry for Engineering
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• v.25 no.3
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• pp.318-323
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• 2014

In order to analyze the effect of maleic anhydride (MAH) content and styrene monomer (SM)/MAH mole ratio on reactive extrusion of maleic anhydride grafted random polypropylenes (MAH-g-rPP), MAH-g-rPPs were prepared by using a twin screw extruder. MAH contents were 0.5, 1.0, 3.0, and 5.0 phr and SM/initiator mole ratio was 0.0, 1.0, and 2.0. Dicumyl peroxide (DCP) was used as an initiator. The graft degree of MAH was confirmed by the existence of carbonyl group (C = O) stretching peak at $1700cm^{-1}$ from FT-IR spectrum. The degree of graft reaction increased up to 3.0 phr MAH and showed the optimum value at 1.0 SM/MAH mole ratio from the area ratio of C = O and C-H stretching peak. Thermal and crystallization properties of MAH-g-rPP and PP/MAH-g-rPP/pulp composites were investigated by DSC, TGA, XRD, and POM. There was a decrease in non-isothermal crystallization temperature of PP/MAH-g-PP/pulp composites. Based on tensile properties and SEM pictures for the fractured surface of PP/MAH-g-PP/pulp composites, MAH content of 1.0 wt% and SM/MAH mole ratio of 1.0 were the optimum formulation as the compatibilizer. The rheological properties of the composites were measured by dynamic Rheometer to compare the processability of the composites with and without compatibilizer. The power law index showed slightly low value at the composites with compatibilizer.