• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.26 no.11C
• /
• pp.64-74
• /
• 2001

In this paper, a dynamic minislot reservation protocol(DMRP) is proposed and analyzed to improve the performance of the multicast traffic processing in wavelength division multiplexing(WDM) networks. For the proposed protocol analysis, the WDM network architecture with a passive star coupler is used. One pair of transceiver is used for a control channel and the ocher pair of transceiver with one fixed transmitter and one tunable receiver are used for data transmission. In this protocol. the packets which fail to have successful transmission in the present time slot due to data channel and destination collisions, have priority to have successful reservation in the contention-less minislots of the next time slot. Therefore, protocols have improved the throughput and the system delay performance caused by the reduced probabilities of control channel contentions and destination collisions probability. Today, the efficient protocol that can handle the various types of data traffic is needed. As results, the DMRP is useful to improve the performance of throughput and system delay characteristics regardless of the kinds of traffic.

• Korean Journal of Optics and Photonics
• /
• v.10 no.2
• /
• pp.162-168
• /
• 1999

A new design of four-pass dye laser amplifier affording a narrow-bandwidth pulsed output is demonstrated to suppress the amplified spontaneous emission(ASE) carried by the amplifier output and reduce the possibility of parasitic oscillation in the amplifier. By the direct pulsed amplification of a cw 100 mW dye laser under a Q-switched doubled Nd:YAG laser pumping with energy of 5.6 mJ/pulse, high-peak-power pulsed output with 1.5-mJ energy in 130-MHz bandwidth is obtained corresponding to a power gain greater than $2{\times}10^6$ and an energy efficiency of 27%. The ASE ratio in the four-pass amplifier output is dramatically reduced by using a diffraction grating in the amplifier. Compared with the results obtained from the normal operation of the amplifier with no frequency-selective device, the ASE ratio is reduced by a factor in excess of 10 to remain under 1.5% of the amplifier output whereas the total output energy is slightly increased by ~4%.

• Korean Journal of Optics and Photonics
• /
• v.17 no.3
• /
• pp.216-222
• /
• 2006

We propose the use of the Gaussian-curve fitting algorithm for the improvement of measurement accuracy in wavelengthscanned Fabry-Perot filter based demodulation systems. The peak locations of FBG sensors were calculated from the fitted curves rather than from distorted PD profiles, resulting in much better measurement accuracy than that of the highest-peak search algorithm. Also, the algorithm was proved to minimize measurement uncertainty of spectrally-distorted grating sensors. From our experimental results, a temperature resolution as small as ${\sim}0.3^{\circ}C$ was readily achieved by use of the Gaussian-curve fitting algorithm whereas the highest-peak search algorithm gave a temperature resolution larger than ${\sim}4^{\circ}C$.

• Proceedings of the Korean Society for Bioinformatics Conference
• /
• 2006.02a
• /
• pp.57-61
• /
• 2006

Microarray란 유리, 실리콘, 플라스틱 등의 매체위에 생체분자를 집적하여 만든 플랫폼을 의미한다. 현재 이러한 플랫폼에 DNA, 화학물질, 유기물질 등 바이오소재를 집적하여 다양한 연구용 제품들이 출시되어 있으며, 수년간 Microarray를 이용한 연구가 진행되어 최근에는 질병진단/예후예측 등의 포괄적인 정보를 포함하는 임상용 microarray제품도 등장하고 있다. 디지탈지노믹스(주)는 2000년 이후로 6년의 기간동안 연구자에게 다양한 종류의microarray를 공급하여 왔으며, 현재 국내에서 가장 많은 종류의 microanay 분석 시스템을 확보하고 있다. 따라서 다양한 연구자들에게 가장 적합한 microarray를 소개할 수 있음은 물론, 그 결과분석 데이터를 제공함으로써 양질의 데이터와 서비스를 제공하고 있다. 특히 디지탈지노믹스(주)에서는 최근에 Combimatrix사의 microarray 시스템을 도입하여, 연구자가 원하는 맞춤형 microarray를 제작할 수 있는 새로운 형태의 차세대 플랫폼을 제공할 수 있게 되었다. 이 기술은 연구자의 목적에 맞게 microarray 제작이 가능하도록 가변적인 특성을 가지고 있으며 높은 민감도 및 재현성을 보여주는 우수한 기술력을 보여준다. Microarray 분야는 그 플랫폼과 분석기술이 나날이 발전하고 있으며, 그 응용범위도 날로 넓어 지고 있다. 그 활용범위의 예를 보면, 1) 유전체 수준에서 발현양상 분석, 2) 약물에 대한 반응성 분석, 3) 질환에 대한 원인 유전자 규명 및 진단제 개발, 4) 독성유전체에서의 약효 및 유효성 분석, 5) 대량의 SNP 분석, 6) 대량의 단백질 수준에서의 발현분석 등이 있으며, 일일이 다 언급하기 힘들 정도로 그 응용범위가 넓어지고 있다. 이러한 microarray기술은 관심 있는 대상에 대한 검색(screening)의 기능과 더불어 분석된 데이터를 기초로 제품화 플랫폼으로써 다시 활용될 수 있는 장점을 가지고 있다. 디지탈지노믹스(주)에서는 구축되어 있는 microarray 분석 시스템을 이용하여 질병 진단, 약물반응성 진단 및 플랫폼 개발에 대한 내부연구도 심도 있게 수행하고 있으며, microarray 기술을 응용하여 산업화, 제품화 할 수 있는 구체적인 사례와 모범답안을 만들기 위해 노력하고 있다.

• Korean Chemical Engineering Research
• /
• v.55 no.2
• /
• pp.230-236
• /
• 2017

Solubility data of carbon dioxide ($CO_2$) in poly(ethylene glycol) dimethyl ether (PEGDME) are presented at pressures up to about 50 bar and at temperatures between 303 K and 343 K. The solubilities of $CO_2$ were determined by measuring the bubble point pressures of the $CO_2+PEGDME$ mixtures with various compositions using a high-pressure equilibrium apparatus equipped with a variable-volume view cell. To observe the effect of the PEGDME molecular weight on the $CO_2$ solubility, the $CO_2$ solubilities in PEGDME with two kinds of molecular weight were compared. As the equilibrium pressure increased, the $CO_2$ solubility in PEGDME increased. On the other hand, the $CO_2$ solubility decreased with increasing temperature. When compared at the same temperature and pressure, the PEGDME with a higher molecular weight gave smaller $CO_2$ solubility on a mass fraction and molality basis, but gave greater $CO_2$ solubilities on a mole fraction basis.

• Transactions of the KSME C: Technology and Education
• /
• v.3 no.1
• /
• pp.1-13
• /
• 2015

In this study, a new dynamic VRF-type heat pump simulation model is proposed which incorporates frosting and defrosting models. Toward this end, a simple frosting model based on the perfect analogy, and lumped system based defrost model, are proposed. Then, frosting and defrosting models are incorporated into a dynamic heat pump model which adopts segment-by-segment local heat exchanger model and map-based variable speed compressor model. Thus, the model can naturally represent locally uneven frosting and defrosting on the heat exchanger surface. Developed simulation model is validated against available experimental data to show good agreement within 10% error for capacity and COP. Finally, developed dynamic heat pump model is applied to annual heating season simulation to show that seasonal COP of heat pump is degraded by 7% due to frosting and defrosting.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.6A
• /
• pp.608-616
• /
• 2007

OFDM Systems for multi-user use adaptive modulation and ending (AMC) which is a method that selects suitable modulation order and code rate depending on channel state of each user. Using AMC, OFDM system can provide high quality and reliable communication. Base station using AMC scheme requires downlink channel information of each terminal to operate optimality. However, under practical system environment, it is unsuitable to transmit all channel information because uplink bandwidth of the system is limited. In this paper, we propose a flexible block-wise loading (FBL) algorithm combined with a novel CQI feedback scheme with reduced number of required bits to optimize the performance of AMC system. Proposed algorithm allocates sub-carrier groups dynamically to improve the sector throughput and outage probability performance.

• Journal of Biomedical Engineering Research
• /
• v.22 no.6
• /
• pp.503-510
• /
• 2001

In this paper. we describe a 32-channel bioimpedance measurement system It consists of 32 independent constant current sources of 50 kHz sinusoid. The amplitude of each current source can be adjusted using a 12-bit MDAC. After we applied a pattern of injection currents through 32 current injection electrodes. we measured induced boundary voltages using a variable-gain narrow-band instrumentation amplifier. a Phase-sensitive demodulator. and a 12-bit ADC. The system is interfaced to a PC for the control and data acquisition. We used the system to detect anomalies with different resistivity values in a saline Phantom with 290mm diameter The accuracy of the developed system was estimated as 2.42% and we found that anomalies larger than 8mm in diameter can be detected. We Plan to improve the accuracy by using a digital oscillator improved current sources by feedback control, Phase-sensitive A/D conversion. etc. to detect anomalies smaller than 1mm in diameter.

• Smart Media Journal
• /
• v.5 no.1
• /
• pp.24-29
• /
• 2016

To satisfy the needs of high-level intelligent surveillance system, it shall be able to extract objects and classify to identify precise information on the object. The representative method to identify one's identity is face recognition that is caused a change in the recognition rate according to environmental factors such as illumination, background and angle of camera. In this paper, we analyze the robust face recognition of face image by changing the distance through a variety of experiments. The experiment was conducted by real face images of 1m to 5m. The method of face recognition based on Linear Discriminant Analysis show the best performance in average 75.4% when a large number of face images per one person is used for training. However, face recognition based on Convolution Neural Network show the best performance in average 69.8% when the number of face images per one person is less than five. In addition, rate of low resolution face recognition decrease rapidly when the size of the face image is smaller than $15{\times}15$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.16 no.6
• /
• pp.40-50
• /
• 2002

In this paper, we present a GA(Genetic Algorithm) approach to select weighting matrices of an optimal LQ(Linear Quadratic) controller for SVC(Static VAR Compensator). A SVC, one of the FACTS(Flexible AC Transmission System), constructed by a FC(Fixed Capacitor) and a TCR(Thyristor Controlled Reactor), was designed and implemented to improve the damping of a synchronous generator, as well as to control the system voltage Also, a design of LQ controller depends on choosing weighting matrices. The selection of weighting matrices which is not a trivial solution is usually carried out by trial and error. We proposed an efficient method using GA of finding weighting matrices for optimal control law. Thus, we proved the usefulness of proposed method to improve the stability of single machine-infinite bus with SVC system by eigenvalues analysis and simulation.