• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2594-2603
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• 1997

A novel method of adaptive beam forming is presented in this paper. The proposed technique provides for a suboptimal beam pattern that increases the Signal to Noise/Interference Ratio (SNR/SIR), thus, eventually increases the capacity of the communication channel, under an assumption that the desired signal is dominant compared to each component of interferences at the receiver, which is precoditionally achieved in Code Division Multiple Access (CDMA) mobile communications by the chip correlator. The main advantages of the new technique are:(1)The procedure requires neither reference signals nor training period, (2)The signal interchoerency does not affect the performance or complexity of the entire procedure, (3)The number of antennas does not have to be greater than that of the signals of distinct arrival angles, (4)The entire procedure is iterative such that a new suboptimal beam pattern be generated upon the arrival of each new data of which the arrival angle keeps changing due tot he mobility of the signal source, (5)The total amount of computation is tremendously reduced compared to that of most conventional beam forming techniques such that the suboptimal beam pattern be produced at vevery snapshot on a real-time basis. The total computational load for generating a new set of weitht including the update of an N-by-N(N is the number of antenna elements) autocovariance matrix is $0(3N^2 + 12N)$. It can further be reduced down to O(11N) by approximating the matrix with the instantaneous signal vector.

• Journal of Korean Library and Information Science Society
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• v.36 no.2
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• pp.263-281
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• 2005

This study was to elucidate the theoretical backgrounds and realities of consumer health information services from a review of the literature, to manifest the actual conditions of consumer health information services by domestic hospital libraries and public libraries, and then to activate library services at least to meet the needs of the services by enhancing their role for consumer demand for health information. This paper propose to activate consumer health information services, as follows : First, librarians both in hospital and in public libraries cognize that consumer health information services really are needed. Furthermore, they expect that when consumer health information services are implemented, the function of the library would be expanded even to the realm of preventive health medical care for consumers and as well as to the patients' right to know. Second, it is recommended that hospital libraries should actively perform their consumer health information services, along with the active collection of health information and materials and develop related bibliographies for hospital libraries to provide patients and their families with medical information. Public libraries also are required to actively collect, maintain and manage health information and to equip themselves with special books in their reference rooms. Third, it is recommended to launch such a cooperation network with a subsystem of MEDLIS as CHIN or CHIPS in the United States of America, to construct an integrated database of consumer health information and materials, an interlibrary system, a reference room service system as well as a cooperation network among hospital and public libraries.

• Journal of the Korean Vacuum Society
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• v.20 no.4
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• pp.288-293
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• 2011

We investigated the effects of piezoelectric field on the electro-absorption characteristics in InGaN/GaN multiple-quantum well (MQW) green light emitting diodes (LED). Double crystal X-ray diffraction measurement was performed to study the crystalline property and indium (In) composition in the MQW active layer. To measure the electro-luminescence and electro-reflectance (ER) spectroscopy, we fabricated the $1{\times}1\;mm^2$ large-area green LED chip. The piezoelectric field inside the LED structure was evaluated from the Vcomp in active layer by the ER spectra. Finally, we analyzed the electro-absorption characteristics of the green LED by using the photo-current spectroscopy.

• Journal of Wetlands Research
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• v.18 no.2
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• pp.194-200
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• 2016

The impervious surface rate increased by urbanization causes various problems on the environment such as water cycle distortion, heat island effect, and non-point pollutant discharges. The Low Impact Development (LID) techniques are significantly considered as an important tool for stormwater management in urban areas and development projects. The main mechanisms of LID technologies are hydrological and environmental pollution reduction among soils, media, microorganisms, and plants. Especially, the media provides important functions on permeability and retention rate of stormwater runoff in LID facilities. Therefore, this research was performed to assess the pollutant removal efficiency for different types of media such as zeolite, wood chip, bottom ash, and bio-ceramic. All media show high pollutant removal efficiency of more than 60% for particulate materials and heavy metals. Double layered media is more effective in reducing heavy metals by providing diverse sizes of micro-pores and macro-pores compared to the single layered media. The results recommend the use of different sizes of media application is more cost-effective in LID than a single size of media. Furthermore, soluble proportion of total heavy metal in the stormwater is an important component in proper media selection and arrangement.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.545-554
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• 2003

Design of the optical modulator composed of a three-waveguide coupler and CPW traveling-wave electrodes was carried out. Switching phenomena of three-waveguide couplers were analyzed by using the coupled mode theory, and the coupling-lengths of the devices were calculated by means of the FDM. CPW traveling-wave electrodes were analysed by the CMM and SOR simulation technique in order to find the conditions of phase-velocity and impedance matching. Traveling-wave modulators were fabricated on z-cut LiNbO$_3$ substrate. Ti was in-diffused in LiNbO$_3$ to make waveguides and Au electrodes were built on the waveguides by the electrolyte technique. The fabricated modulator chip was end-polished, pig-tailed and packaged in a brass mount with K-connector. The insertion loss and the switching voltage of the optical modulator were about 4㏈ and 19V, respectively. Network analyzer was used to obtain the S parameter and the corresponding RF response. From the measurement, parameters of the traveling-wave electrodes were extracted to be Z$_{c}$= 45 Ω, N$_{eff}$=2.20, and $\alpha$$_{0}$=0.055/cm√GHZ. The measured optical response R($\omega$) was compared with the theoretically estimated one, showing both responses agree well. The measurement results revealed that 3㏈ bandwidth turned out to be about 13 GHz.

• Korean Journal of Optics and Photonics
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• v.31 no.5
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• pp.213-217
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• 2020

In this study we report a wet-etching-based fabrication method for adiabatic optical-fiber tapers (OFTs), and describe their adiabaticity and HE₁₁ mode evolution at a wavelength of 1550 nm. The profile of the fabricated system satisfies the adiabaticity properties well, and the far-field pattern from the etched OFT shows that the fundamental HE₁₁ mode is maintained without a higher-order mode coupling throughout the tapers. In addition, the measured far-field pattern agrees well with the simulated result. The proposed adiabatic OFTs can be applied to a number of photonic applications, especially fiber-chip packages. Based on the fabricated adiabatic OFT structures, the optical transmission to the inversely tapered silicon waveguide shows large spatial-dimensional tolerances for 1 dB excess loss of ~60 ㎛ (silicon waveguide angle of 1°) and insertion loss of less than 0.4 dB (silicon waveguide angle of 4°), from the numerical simulation. The proposed adiabatic coupler shows the ultrabroadband coupling efficiency over the O- and C-bands.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.1 s.343
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• pp.27-36
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• 2006

Conventional delay-insensitive (DI) data encodings usually require 2N+1 wires for transferring N-bit. To reduce complexity and power dissipation of wires in designing a large scaled chip, an encoder and a decoder circuits, where N-bit data transfer can be peformed with only N+l wires, are proposed. These circuits are based on a quasi delay-insensitive (QDI) model and designed by using current-mode multiple valued logic (CMMVL). The effectiveness of the proposed data transfer mechanism is validated by comparisons with conventional data transfer mechanisms using dual-rail and 1-of-4 encodings through simulation at the 0.25 um CMOS technology. In general, simulation results with wire lengths of 4 mm or larger show that the CMMVL scheme significantly reduces delay-power product ($D{\ast}P$) values of the dual-rail encoding with data rate of 5 MHz or more and the 1-of-4 encoding with data rate of 18 MHz or more. In addition, simulation results using the buffer-inserted dual-rail and 1-of-4 encodings for high performance with the wire length of 10 mm and 32-bit data demonstrate that the proposed CMMVL scheme reduces the D*P values of the dual-rail encoding with data rate of 4 MHz or more and 1-of-4 encoding with data rate of 25 MHz or more by up to $57.7\%\;and\;17.9\%,$ respectively.

• Journal of the Korean Arthroscopy Society
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• v.3 no.1
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• pp.40-43
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• 1999

Arthroscopic anterior cruciate ligament(ACL) reconstruction using four-strand hamstring tendon with looping around transfixing screw in femoral tunnel requires osteointegration between the grafted tendon and bone for stability of the knee. Authors have experienced a histologic finding of osteointegration between the grafted autogenous hamstring tendon and bone in femoral tunnel after arthroscopic ACL reconstruction. A patient received arthroscopic ACL reconstruction with autogenous four strand hamstring tendon for the ACL injury. Traumatic re-rupture of mid-substance of ACL graft was developed at thirteenth week after operation. During the procedures of arthroscopic revision at fifteenth week after initial ACL reconstruction, biopsy was performed at the site of interface between grafted tendon and bone in femoral tunnel. Integration between the grafted tendon and bone was evident by demonstrating the continuity of collagen fiber between bond and tendon. This histologic finding and the low incidence of early graft failure suggest that free tendon autograft attached to bone by looping around a transfixing screw in femoral tunnel undergoes adequate osteointegration between 12 and 15 weeks after surgery and authors thought that insertion of bone chip into the femoral tunnel would accelerate osteointegration procedure.

• IMMUNE NETWORK
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• v.5 no.4
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• pp.205-214
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• 2005

Background: We examined global gene expression profiles of peripheral blood mononuclear cells (PBMCs) in patients with ulcerative colitis (DC), and tested whether the identified genes with the altered expression might be associated with susceptibility to UC. Methods: PBMCs from 8 UC and 8 normal healthy (NH) volunteers were collected, and total RNAs were subjected to the human 8.0K cDNA chip for the micro array analysis. Real time-PCR (RT-PCR) was performed to verify the results of micro array. One hundred forty UC patients and 300 NH controls were recruited for single nucleotide polymorphism (SNP) analysis. Results: Twenty-five immune function-related genes with over 2-fold expression were identified. Of these genes, two chemokines, namely, CXCL1 and CCL20, were selected because of their potential importance in the evocation of host innate and adaptive immunity. Four SNPs were identified in the promoter and coding regions of CXCL1, while there was no significant difference between all patients with UC and controls in their polymorphisms, except minor association at g.57A>G (rs2071425, p=0.02). On the other hand, among three novel and one known SNPs identified in the promoter region of CCL20, g. -1,706 G>A (p=0.000000055), g. -1,458 G>A (p=0.0048), and g. -962C>A (p=0.0006) were found to be significantly associated with the susceptibility of Uc. Conclusion: Altered gene expression in mononuclear cells may contribute to IBD pathogenesis. Although the findings need to be confirmed in other populations with larger numbers of patients, the current results demonstrated that polymorphisms in the promoter region of CCL20 are positively associated with the development of Uc.

• Journal of the Korea Society of Computer and Information
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• v.19 no.4
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• pp.1-8
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• 2014

As cores in multi-core processors are integrated in a single chip, power density increased considerably, resulting in high temperature. For this reason, many research groups have focused on the techniques to solve thermal problems. In general, the approaches using mechanical cooling system or DTM(Dynamic Thermal Management) have been used to reduce the temperature in the microprocessors. However, existing approaches cannot solve thermal problems due to high cost and performance degradation. However, floorplan scheme does not require extra cooling cost and performance degradation. In this paper, we propose the diverse floorplan schemes in order to alleviate the thermal problem caused by the hottest unit in multi-core processors. Simulation results show that the peak temperature can be reduced efficiently when the hottest unit is located near to L2 cache. Compared to baseline floorplan, the peak temperature of core-central and core-edge are decreased by $8.04^{\circ}C$, $8.05^{\circ}C$ on average, respectively.