• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.7
• /
• pp.723-730
• /
• 2007

This paper shows how the ACLR of power amplifier can be reduced by using Anti-phase IMD linearization technique which generate anti-phase IMD in the driver stage compare to output stage's IMD. And design process proposed. From the experimental result of W-CDMA 4FA input signal, this amplifier has ACLR -55 dBc@5 MHz offset at 30 watts average power. Compare to optimum matching technique to get maximum power gain, this technique has been improved ACLR by 12 dBc. Also this amplifier meets 50 watts average output power amplifier specification in domestic market.

• 한국생물공학회:학술대회논문집
• /
• 2003.04a
• /
• pp.750-753
• /
• 2003

A method for the mass production was designed by using a screw pumping system that can supply safe bifidobacteria. To prevent the inhibition of cell activity, various additives, which are able to preserve pore of an alginate bead, were used. When materials are sterilized, viscosity decreased below 300cp. Adding bifidobacteria, viscosity increased to 300cp. We manufactured various extrusion nozzles and tested mass productivity of the alginate bead. As a result, 18G, 4mm length sylinge with 13 multi-nozzle showed the best productivity which was about $308{\pm}3ea/min$.

• Fashion & Textile Research Journal
• /
• v.11 no.6
• /
• pp.918-924
• /
• 2009

As the population of overweight and obese children is rising rapidly around the world, there are many researches on purchasing and wearing children's clothing and optimal sizes, but researches on obese children are still inadequate. This study was carried out on 192 obese children over 75% in BMI. The purpose of the study was to set up the optimal interval of sizing system using the loss function which would be a guide for obese children for selecting ready to wear of suitable size. Introducing a loss function, which reflects how much the purchasing desire changes according to the difference, we formulate the problem and suggest a procedure to determine the optimal standard sizes minimizing the loss. These results were as follows ; In size chart of top's, 4 sizes had been determined by a loss function, had covered more than 91.1% of all subjects. In size chart of bottom's, 5 sizes had been determined by a loss function, had covered more than 87.0% of all subjects.

• Journal of Satellite, Information and Communications
• /
• v.2 no.2
• /
• pp.59-63
• /
• 2007

In this paper, we propose an advanced Ka-band satellite HD broadcasting system using scalable video coding technology. As already known, it is not so easy to achieve reasonable link availability on Ka-band because of the rain-attenuation effect, and in case of HD broadcasting service it's more difficult. To overcome that problem, we propose an hierarchical broadcasting system based on H.264 SVC technology. In this paper, we suggest a few types of system scenario to realize the concept. Those scenarios are including DVB-S and DVB-S2 and spatially scalable video stream is the source stream in all cases.

• Proceedings of the KIPE Conference
• /
• 2008.06a
• /
• pp.244-246
• /
• 2008

본 논문에서는 LCD TV의 인치에 따라 다르게 적용되는 기존의 전원 구동 분리형 시스템과 전원 구동 IP 시스템을 검토하여, 두 시스템의 장점만을 모아 LCD TV 전원 시스템의 표준화가 가능한 새로운 방식의 구동 전원 통합 시스템을 제안한다. 제안 시스템은 가격 및 효율이 우수한 2단 구성으로 이루어져 있고, 안전규격을 만족하기 위하여 EMI측면에 유리한 1:1 Trans.를 사용하였다. 인버터 부의 최적 동작을 위해 인버터 구동신호의 주파수와 시비율을 고정하고 펄스 개수를 제어하는 Pulse Count Modulation(PCM)방식을 채용 하였다. 제안 시스템의 인버터단은 전 부하 범위에서 영전압 스위칭이 가능하여 스위치의 발열이 우수하고, 별도의 전류 평형 Trans.가 필요치 않으므로 Balance Coil의 삭제가 가능하다. 이로 인해 신뢰성이 높은 제품 구성이 가능하고, PCB Size 축소 및 제품 제작 단가가 낮아지는 장점을 갖는다. 최종적으로 제안 시스템을 기존 시스템과 비교 및 실험적 검증을 통하여 제안 시스템의 그 우수성을 확인한다.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.32 no.5A
• /
• pp.441-450
• /
• 2007

In this paper, it is proposed the link performance analysis results using SNRAT(Satellite Network Resource Allocation & Analysis Tool) and verified the anticipated results by satellite communication network simulator. A communication satellite cannot be corrected or fixed for the error in orbit operation after launching unlike the ground operation equipment and has a restricted operation life. So, it is important to make possible to use satellite communications in the proper time. It is expected the link BER(Bit Error Rate), throughput and AJ(Anti-Jamming) performance using SNRAT tool before launching. And it is verified the performance of the repeaters and ground equipment specification using the satellite network simulator and is extracted the optimum operational scenarios through the tests of various network operational plans.

• Proceedings of the KIEE Conference
• /
• 2006.07a
• /
• pp.254-255
• /
• 2006

최근의 전력시스템 분야에서는 IT기술의 혁신적인 발전과 향후 전개될 유비쿼터스 네트워크 사회에서의 전력시스템 분야의 역할 및 발전 방향에 대한 많은 의견이 있었다. 이러한 노력은 IT기술과 유비쿼터스 네트워크 기술을 전력분야에 적용하여 지능화된 전력네트워크 감시 및 제어시스템을 구현하는 방향으로 전개되고 있다. 전력시스템을 구성하는 주요 시설물을 감시하고 유지하기 위한 방안으로 센서 및 센서네트워크의 구현을 통한 지능형 감시 체계를 구현하는 방법이 논의되고 있다. 전력계통시스템을 감시하기 위하여 사용되는 각종 센서 및 액츄에이터에서 계측된 데이터를 규격화하는 방법을 규정한 IEEE 1451 과 디지털변전소의 통신을 위한 프로토콜로 여겨지는 IEC 61850 규격은 전력설비내의 센서 및 센서네트워크를 구성하는 주요 프로토콜로서 프로토콜간의 상호 연계 및 변환 기술의 개발은 네트워크 시스템의 운용 성능에 직결된다. 그러므로 IEEE 1451과 IEC 61850의 연구를 통하여 최적의 지능형 전력네트워크 구현하기 위한 변환기술이 필요하다.

• Korean Journal of Optics and Photonics
• /
• v.7 no.4
• /
• pp.375-385
• /
• 1996

Recently interest in the fabrication of LD operated by low current is gradually increasing as fabrication techniques of MQW-LD are progressed. In this viewpoint, theoretical estimation for decreasing the amount of threshold current will be helpful to design and make LD in case that active layer of conventional bulk type RWG-LD structure is replaced with MQW structure. Therefore, the optimum design condition of RWG MQW-LD was obtained from theoretical analysis in order to operate in the weakly index-guided LD and low threshold current. The lateral effective index step has been obtained in RWG MQW-LD structure. Waveguide mechanism including this index step has been investigated by solving the carrier diffusion equation and lateral wave equation. From these theoretical results, the optimum design condition of RWG MQW-LD have been suggested.

• The Journal of the Acoustical Society of Korea
• /
• v.16 no.5
• /
• pp.12-17
• /
• 1997

In this work, we developed a new type ultrasonic dehumidifier with piezoelectric ceramics, which and efficiently repel waterdrops on outdoor glass plates exposed to raindrops. Through finite element analysis of a certain type of glass plates to analyze its dynamic behavior, the structure of the ultrasonic device we determined to get the optimal performance. A supplemental metal plate was attached to the glass plate for uniform cleaning. Based on the theoretical results, experimental samples were fabricated and evaluated with various dimensions of the glass plate and the piezoceramic vibrator. Driving circuit for the dehumidifier made use of the frequency sweeping technique to keep track of the resonant frequency of the glass plate that was variant with environmental conditions.

• Journal of the Korean Institute of Gas
• /
• v.18 no.2
• /
• pp.81-86
• /
• 2014

The analysis of the cost optimization and the total demand weight of 9% Ni-steel plates for installing shell stiffeners in the side wall of the large capacity LNG storage tank are carried out in order to reduce the costs of the plates for stiffeners. This study can be possible for developing the calculation program which evaluates the bill-of-material for stiffeners to reduce the manual calculation time of tank designer, and to enable the estimation of weight and cost for various plate width. The results show that the demand weight and cost are reduced as the plate width is wider. Nevertheless, both the weight and the cost with plate width for stiffeners should be compared and evaluated to obtain the optimum cost time to time because of various cost incremental factors of plates such as transportation and handling cost, etc.