• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.3
• /
• pp.20-40
• /
• 2003

Since unloaded Q-value of a high-temperature superconductor(HTS) filter is very high, a bandpass filter(BPF) and a lowpass filter(LPF) with an increase of pole numbers can be fabricated without an increase of an insertion loss(IL) ; recently a 70-pole BPF is developed in USA. They have an abrupt skirt property and an excellent attenuation level for out-of band. Moreover, they can be miniaturized when lumped element resonators or the slow-wave characteristic are used. Technology of fabricating a HTS epitaxial film as well as a film of a 4 inch area also makes the planar type filter with a various structure and an enhanced power handling capability possible. Recently, the HTS filter subsystems composed of a planar-type HTS filters, a GaAs-based LNA and a mini-cryocooler are developed. The extended receiver front- end subsystems for mobile radio communications decrease the noise-figure level of the communication system and the frequency interference interacted adjacent bands, and increase the efficiency of frequency and the capacity of communication system. In this paper, theory for developing the HTS filter, its kinds, its design rules, its characteristics are reviewed. The feature of the research and market trends related to the HTS filter systems for the receiver front-end subsystem of mobile base station are surveyed.

• 한국해양학회지
• /
• v.29 no.4
• /
• pp.392-401
• /
• 1994

We examined the temporal characteristics of the oceanic eddy diffusion at 5 coastal regions of Korea by measuring the separation distances of multiple drifters released simultaneously at the same by the GPS and Decca transponder system. The observed variance of separation distance, for the time scales from minutes to hours, is proportional to t/SUP m/ with scaling exponent m between 1.2 and 2.0. The observed Lagrangian trajectories of drifters show fractal characteristics instead of random walk or Brown motion. As an effort toward a development of a realistic model of the oceanic eddy diffusion, we simulated the Lagrangian trajectories of drifters by fractional Brown motion (FBM) model. The observed variances of drifter separations can be generated by the FBM process provided the Hurst exponent is the same as the observed one. We further showed that the observed power law in the variance of drifter separations cannot be simulated with an ordinary Brown motion or random walk process.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.12
• /
• pp.3577-3588
• /
• 1999

This paper describes design and implementation of a general purpose cyber educational system. In this system, there are different types of menus and services according to such user's rights as system operators, professors, assistant instructors, students. In order to keep in close contact between students and professors, provided are various services such as the official announcement, transcripts of lecture, bulletin board, Q/A corner, report box, archive of study materials, electronic mail box, memorandum including checking of one's attendance and school record. For the purpose of activating small group studies and discussion about given subject, it can organize into groups automatically and provide with debating rooms. The system is implemented by separating with both HTML design and programming part by templete concept. Overload of iterative server is solved by adjusting the numbers of DB servers of each service.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.38 no.12
• /
• pp.1367-1372
• /
• 2014

As the awareness of the environmental crisis has recently increased around the world, numerous studies in the transport industry have been conducted to solve this problem through lightweight car bodies. The hot-stamping process has been presented as solution to achieve a light weight. Hot-stamping is a method that is used to obtain ultra-high strength steel (1,500 MPa or greater) by simultaneously forming and cooling boron steel in a press die after heating it to a temperature of $900^{\circ}C$ or above. This study involved a, fundamental examination of laser parameters to investigate the laser weldability of boron steel. As a result, the following optimum parameters for the shielding gas were found: Q = 20 l/min, ${\alpha}=40^{\circ}$, d = 20mm, and l = 0 mm. The hardness of butt weldment increasesed sharply as a result of martensite formation at the fusion zone.

• Microbiology and Biotechnology Letters
• /
• v.30 no.3
• /
• pp.235-240
• /
• 2002

Streptomycetes is a group of Gram-positive soil bacteria that growas a branching vegetative mycelium leading to the formation of spores, and display a physiological differenti-ation related to the synthesis of many secondary metabolites including antibiotics. Their complex life cycle and multicellular differentiation require various levels of regulation and types of signal transduction systems including eukaryotic-type serine/threonine protein kinases and prokaryotic-type histidine/aspartic acid protein kinases. Akt kinase that was found in cells is a sorine/threonine kinase controlling signal pathway for multi-tude of important cellular events. The activation or inactivation of Akt kinase in the cell is one of the critical regulatory points to deliver cell proliferation, differentiation, survival or apoptosis signal. To find the regula-tory protein homologous to Akt in Streptomyces, the fluorescien-labeled synthetic peptide (FITC-TRRSR-TESIT) was designed from the consensus sequence of target proteins for Akt kinase. From the difference of the mobility between the nonphosphorylated and phosphorylated synthetic peptides on Agarose gel electro-phoresis, the Akt-phosphorylating activity was monitored. The cell-free extract prepared from Streptomyces griseus IFO 13350 and the Akt homologous protein was purified by ammonium sulfate fractionation and many steps of column chromatographies such as, DEAE-Sepharose, Mono Q, Resource Phenyl-Soporose and Gel permeation column chromatographies. As a result, the protein phosphorylating the fluorescien-labeled Akt substrate was identified and it's molecular weight was estimated as 39 kDa on SDS-PAGE.

• Journal of the Korean Orthopaedic Association
• /
• v.56 no.2
• /
• pp.134-141
• /
• 2021

Purpose: Patellar dislocations have a range of causes. This study examined the results of treatment aimed at balancing soft tissues around the patella. Materials and Methods: Thirty-two patellar dislocations in 28 patients (21 females and seven males) were examined. The mean patient age at the time of surgery was 11.5 years, and the mean follow-up period was 4.6 years. Dislocations were 19 chronic, six habitual, six congenital, and one acute. Soft tissue balancing surgery included lateral capsular release, medial capsular plication, and inferolateral transfer of the vastus medialis obliquus. Medial transfer of the patellar tendon, partial strip of the rectus femoris and patella tendon, and distal femoral osteotomy were also performed selectively. The preoperative Q angle, femoral anteversion angle, tibial external rotation angle, tibial tubercle-trochlear groove distance (TT-TG distance), mechanical femoral-tibial angle, and femoral trochlear dysplasia according to Dejour were measured, and the pre- and postoperative Lysholm-Tegner scores were used to analyze the clinical results. Results: The mean preoperative Q angle, TT-TG distance, femoral anteversion angle, tibial external rotation angle, mechanical femoraltibia angle, and Lysholm-Tegner score were 9.3°, 15.5 mm, 25.6°, 30.4°, 3.0°, and 75.8, respectively. Eleven patients had systemic ligament laxity with a Beighton score of five or more. Twenty-two patients had femoral trochlear dysplasia: four type A (3 patients), 16 type B (15 patients), one type C (1 patient), and four type D (3 patients). Of the 32 cases, 28 were corrected successfully by the first operation. Of four cases of postoperative subluxation, three were corrected by the second operation, and one of them was corrected after a third operation. The last patient is currently being followed-up. The mean Lysholm-Tegner score improved to 85.6 after the operation. Conclusion: Correcting all the causes of patella dislocation simultaneously is difficult. Nevertheless, satisfactory outcomes were obtained with soft tissue balancing surgery around the patella and a corrective osteotomy for an abnormal mechanical axis of the femur-tibia and torsion.

• Journal of the Korean Ceramic Society
• /
• v.41 no.10 s.269
• /
• pp.783-787
• /
• 2004

Microwave dielectric properties and the microstructure of $Ba_5Nb_4O_{15}$ ceramics with $PbO-B_2O_3-SiO_2$ glass frit were investigated to reduce the sintering temperature of $Ba_5Nb_4O_{15}$ ceramics as a function of the amount of glass frit from $0.5wt\%$ to $10wt\%$ and the sintering condition. The sintered density and the microwave dielectric properties of $Ba_5Nb_4O_{15}$ ceramics were remarkably changed with the amount of glass fit which existed as a liquid phase and assisted the densification. $Ba_5Nb_4O_{15}$ with $3wt\%$ $PbO-B_2O_3-SiO_2$ glass frit sintered at $900^{\circ}C$ for 2 h showed dielectric constant (K) of 41.4, a quality factor (Q $\times$f) of 13,485 GHz, and a Temperature Coefficient of resonant Frequency (TCF) of 9 ppm/$^{\circ}C$. Due to no trace of physical and chemical reaction between this composition and Ag electrode cofired at $900^{\circ}C$ for 2 h, this ceramics can be a good candidate for the multilayer dielectric filter.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2013.02a
• /
• pp.608-608
• /
• 2013

직선운동하는 하전입자의 진행방향에 수직한 평면상에 서로 직교하는 전기장과 자기장을 걸어주면, 하전입자에는 전기장에 의한 힘 $F_E$와 자기장과 속도 v에 의한 로렌츠력 $F_B=q(v{\times}B)$가 동시에 작용하게 된다. 이때 Wien 조건 $F_B=-F_E$를 만족하는 질량 $m_A$과, 에너지 $E_A$를 가지는 하전입자 A는 휘지 않고 직선운동을 계속하나, 하전입자 A와 다른 에너지 $E_B(=E_A+{\delta}E)$나 질량 $m_B$ $(=m_A+{\delta}m)$을 가지는 하전입자는 휘게 되며, 그 휘는 정도는 ${\delta}E$나 ${\delta}m$에 비례하게 된다. 이 현상을 이용하여 다양한 종류의 에너지 또는 질량 분석기가 독일, 미국, 일본 등의 분석기기 선진국에서 개발되어 왔고, 전자현미경의 이미지 필터로도 활용되고 있으며, 통상 EXB 필터 또는 발명자의 이름을 딴 Wien 필터로 불리어지고 있다. $E{\times}B$ 필터는 일반적인 하전입자빔 렌즈와 다른 광학특성을 가진다. 예를 들면 3차 이상의 기하 수차만 가지는 일반 렌즈와는 달리 $F_B$, $F_E$ 전자기력에 의해 다양한 2차 기하 수차를 가지게 되며, 초점거리 등의 1차 광학 특성도 일반 렌즈와는 다른 경향을 보여준다. 본 발표에서는 $E{\times}B$ 필터의 전후로 각각 6극자+4극자를 조합시킨 보정기를 배치시켜 필터의 에너지 분해능의 성능을 향상시킬 수 있음을 빔 궤도 방정식을 분석적으로 계산하여 보여준다. 위 에너지 필터 구성에서 4극자는 1차 광학 특성을 조정하는 역할을 하며 6극자는 2차 수차를 줄여주는 역할을 한다. 수치해석을 통해서는 6극자+4극자를 조합시킨 보정기와 $E{\times}B$ 필터의 좀더 정확한 전극 전압 등의 제어 수치를 추출하고, 빔 궤도 방정식 분석을 통한 수차 보정 알고리즘이 유효함을 보여준다.

• Journal of the Institute of Convergence Signal Processing
• /
• v.17 no.2
• /
• pp.83-92
• /
• 2016

In this paper, we introduce the results of the testing and observation systems for performance wideband expansion in the Korean VLBI Network(KVN). The KVN performs VLBI observations to 1024 Mbps data rate, and 8192 Mbps observing for four simultaneous observation is now evaluating for normal operation. The VLBI stations in several world countries developed their own wideband observing systems to observe the celestial objects with high precision and high resolution or are working with several countries. The KVN is planning to introduce a high-speed sampler, OCTAD, for sampling directly up to 2048 MHz bandwidth for RF signal of K/Q/W/D band in the frequency band without conversion. Therefore, as a preliminary study for the performance scalability of the KVN then through the close cooperation with National Astronomical Observatory of Japan (NAOJ), the OCTAD high-speed sampler and OCTADISK2 high-speed recorder were installed in the KVN Yonsei station, and verify the performance through a wideband.

• Archives of design research
• /
• v.19 no.2 s.64
• /
• pp.151-162
• /
• 2006

The purpose of this thesis is to upgrade brand logo's equity by objective and professional evaluating tool. A brand logo is the main factor in making brand equity, but many times a brand logo is decided without objective judgment because making a logo is considered an intuitive process. To minimize the poor judgment by non-experts, a brand logo needs objective numerical grading tool. Thus, a brand logo is a factor in making a brand identity, not only brand image. That is why brand logo must be chosen by an expert's object judgment. The concrete method to obtain a objective, and at the same time professional grading tool which can De used for the developing and verifying process for a brand logo is as below-first, considering brand judgment from various angles through existing literature, I found various logo grading factors and then extracted them with professional identity designer's subjective consideration. second, applying extracted factors to actual logo grading, verify as a efficient design management tool