• Journal of the Institute of Electronics Engineers of Korea SD
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• v.48 no.12
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• pp.45-51
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• 2011

This paper presents a wideband low-noise amplifier (LNA) covering 800MHz~5.8GHz for various wireless communication standards by utilizing in a 0.13um CMOS technology. Particularly, the LNA consists of two stages to improve the low-noise characteristics, that is, a cascode input stage and an output buffer with noise cancellation technique. Also, a feedback resistor is exploited to help achieve wideband impedance matching and wide bandwidth. Measure results demonstrate the bandwidth of 811MHz~5.8GHz, the maximum gain of 11.7dB within the bandwidth, the noise figure of 2.58~5.11dB. The chip occupies the area of $0.7{\times}0.9mm^2$, including pads. DC measurements reveal the power consumption of 12mW from a single 1.2V supply.

• JSTS:Journal of Semiconductor Technology and Science
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• v.14 no.1
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• pp.100-108
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• 2014

Low noise amplifier (LNA) is an integral component of RF receiver and frequently required to operate at wide frequency bands for various wireless system applications. For wideband operation, important performance metrics such as voltage gain, return loss, noise figure and linearity have been carefully investigated and characterized for the proposed LNA. An inductive shunt feedback configuration is successfully employed in the input stage of the proposed LNA which incorporates cascaded networks with a peaking inductor in the buffer stage. Design equations for obtaining low and high impedance-matching frequencies are easily derived, leading to a relatively simple method for circuit implementation. Careful theoretical analysis explains that input impedance can be described in the form of second-order frequency response, where poles and zeros are characterized and utilized for realizing the wideband response. Linearity is significantly improved because the inductor located between the gate and the drain decreases the third-order harmonics at the output. Fabricated in $0.18{\mu}m$ CMOS process, the chip area of this wideband LNA is $0.202mm^2$, including pads. Measurement results illustrate that the input return loss shows less than -7 dB, voltage gain greater than 8 dB, and a little high noise figure around 6-8 dB over 1.5 - 13 GHz. In addition, good linearity (IIP3) of 2.5 dBm is achieved at 8 GHz and 14 mA of current is consumed from a 1.8 V supply.

• Biotechnology and Bioprocess Engineering:BBE
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• v.6 no.6
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• pp.402-409
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• 2001

Different bioligands carrying synthetic adsorbents have been reported in the literature for protein separation, We have developed a novel and new approach to obtain high protein ad-sorption capacity utilizing 2-methacrylamidohistidine(MAH) as a bioligand. MAH was synthe-sized by reacting methacrylocholride and histidine, Spherical beads with an average size of 150-200㎛ were obtained by the radical suspension polymerization of MAH and 2-hydrosyethyl-methacrylate(HEMA) conducted in an aqueous dispersion medium. p(HEMA-co-MAH) beads had a specific surface area of 17.6㎡/g . Synthesized MAH monomer was characterized by NMR. p(HEMA-co-MAH) beads were characterized by swelling test, FTIR and elemental analysis. Then Cu(II) ions were incorporated onto the beads and Cu(II) loading was found to be 0.96 mmol/g.These affinity beads with a swelling ration of 65% and containing, 1.6 mmol MAH/g were used in the adsorption/desorption of human serum albumin(HSA) from both aqueous solutions and hu-man serum. The adsorption of HSA onto p(HEM-co-MAH) was low(8.8 mg/g). Cu(II) chelation onto the beads significantly increased the HSA adsorption (56.3 mg/g). The maximum HSA ad-sorption ws observed at pH 8.0 Higher HSA adsorption was observed from human plasma(94.6 mgHSA/g) Adsorption of other serum proteins were obtained as 3.7 mg/g for fibrinogen and 8.5mg/g for γ-globulin. The total protein adsorption was determined as 107.1mg/g. Desorption of HSA was obtained using 0.1 M Tris/HCl buffer containing 0.5 M NaSCN, High desorption rations(up to 98% of the adsorbed HSA) were observed. It was possible to reuse Cu(II) chelated-p(HEMA-co-MAH) beads without significant decreases in the adsorption capacities.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.10C
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• pp.963-972
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• 2002

An 8192-point pipelined FFT/IFFT processor core is designed, which can be used in multi-carrier modulation systems such as DUf-based VDSL modem and OFDM-based DVB system. In order to improve the signal-to-quantization-noise ratio (SQNR) of FFT/IFFT results, two-step convergent block floating-point (TS_CBFP) scaling is employed. Since the proposed TS_CBFP scaling does not require additional buffer memory, it reduces memory as much as about 80% when compared with conventional CBFP methods, resulting in area-and power-efficient implementation. The SQNR of about 60-㏈ is achieved with 10-bit input, 14-bit internal data and twiddle factors, and 16-bit output. The core synthesized using 0.25-$\mu\textrm{m}$ CMOS library has about 76,300 gates, 390K bits RAM, and twiddle factor ROM of 39K bits. Simulation results show that it can safely operate up to 50-㎒ clock frequency at 2.5-V supply, resulting that a 8192-point FFT/IFFT can be computed every 164-${\mu}\textrm{s}$. It was verified by Xilinx FPGA implementation.

• Journal of Environmental Health Sciences
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• v.36 no.5
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• pp.373-382
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• 2010

A number of recent studies have shown that occupational stress is closely associated with increased fatigue and decreased job satisfaction. This study was designed to assess stress in workers in the field of EIA (environment impact assessment) from July 2009 through september 2009, and questionnaires were uesd to analyze the stress scores and identify the primary factors influencing stress in this occupation. The number of respondents was 272 working in the Capital (Seoul and Kyunggido), Chungcheongdo, Jejudo area. A structured questionnaire was used to evaluate the participants' socio-demographics, job-related factors, health-related behaviors, occupational stress, reaction factor (self-perceived fatigue, job satisfaction) and buffer factor (social support). Occupational stress and self-perceived fatigue were assessed using the Korean Occupational Stress Scale-Short Form (KOSS-SF) and the Multidimensional Fatigue Scale (MFS), respectively. The analysis revealed a strong correlation between occupational stress, job satisfaction, and social support, with occupational stress being associated with an increased risk of fatigue and decreased job satisfaction. In the multiple regression analysis(stepwise), the main factors influencing occupational stress were found to be job satisfaction, supervisor, fatigue, working time, no. of personnel, career. The results of this study suggest that occupational stress is a determinant predictor of self perceived fatigue and job satisfaction. Thus, a strong recommendation is made for a stress management program for reduction of occupational stress, and for the development of relevant experts on the health and quality of life of environment impact assessment workers.

• Journal of the Korean Institute of Landscape Architecture International Edition
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• no.1
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• pp.13-25
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• 2001

Recently there have been increasing demands and desire for the urban open space due to urban development or environmental deterioration. Urban natural parks in Seoul provide citizens with comfortable open space and thus play an important role as learning spaces to experience nature and understand the environment. Accordingly, this study aims to analyze existing vegetation and provide basic data for the conservation and management plans of urban natural parks and education programs. The contents of the study encompass natural environment such as topography, altitude, slope and aspect and botanical ecosystem including the structure of plant communities and tree growth. According to the result of topography analysis, the overall altitude was not high but the slope was relative steep. Vegetation of Seoo Royal Tomb, a urban natural park has been classified into 12 types, and they include; Quercus acutissima community(lowland type), Quercus acutissima community(valley type), quercus variabilis community, Quercus mongolica community, Castanea crenata community, Capinus laxiflora community, Pinus densiflora community(lowland type), Pinus densiflora community(slope type), Robinia pseudo-acacia community, Populos$\times$albaglandulosa community, Pinus rigida community, and Pinus koraiensis community. Based on the survey and analysis results, we have classified the study area into conservation, buffer, and utilization zones for the effective management. This study provides basic data to support the establishment of master plans for urban natural parks by analyzing vegetation conditions at Seoo Royal Tomb, an urban natural park, Based on the results presented in the study, consistent monitoring work needs to be conducted, and elaborate management plans also should be prepared.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.5
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• pp.1015-1022
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• 2012

This paper deals with hardware design which unifies MD5 and HAS-160 hash algorithms. Two algorithms get a message with arbitrary length and process message blocks divided into 512 bits each time and output a hash code with a fixed length. MD5 ouputs a hash code of 128 bits and HAS-160 a hash code of 160 bits. The unified hash core designed has 32% of slices overhead compared to HAS-160 core. However, there is only a fixed message buffer space used. The unified hash core which run a step in one clock cycle operates at 92MHz and has performance which digests a message in the speed of 724Mbps at MD5 and 581Mbps at HAS-160 hash mode. The unified hash core which is designed can be applicable to the areas such as E-commerce, data integrity and digital signature.

• Journal of Pharmaceutical Investigation
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• v.38 no.2
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• pp.99-104
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• 2008

PLGA micro/nano particles encapsulating ranitidine as a hydrophilic model drug were prepared by the double-emulsion solvent evaporation method. Surface morphology investigation by scanning electron microscope (SEM) showed that the emulsification by sonication could produce nanoparticles, whereas microparticles were prepared using high speed homogenizer. Moreover, while nanohalf-shell structure instead of spherical nanoparticle could be produced by adding poloxamer into oil phase (MC) with PLGA 504H, the addition of poloxamer didn't change particle shape in case of PLGA 502H. On the other hand, microparticle with poloxamer had more surface pores than those without poloxamer. The size and polydispersity (PDI) of particles were determined by particle size analyzer. Effective diameters of particles were in the range of $400{\sim}800\;nm$ and $1200{\sim}3300\;nm$ in case of nanoparticles and microparticles, respectively. Encapsulation efficiencies were in the range of $1.2{\sim}2.9%$. The addition of poloxamer produced the particles with higher encapsulation efficiency. In vitro release study in phosphate buffer (pH 7.4) at $37^{\circ}C$ showed common large initial burst release. However, the relative slower release profile could be observed in case of microparticles. Poloxamer addition increased the release rate, which was thought to be related to the increased surface area of particles.

• Environmental and Resource Economics Review
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• v.28 no.4
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• pp.617-643
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• 2019

The Demilitarized Zone(DMZ) is a buffer zone set between the southern and northern limit lines established after the 1953 Armistice Agreement. It is an important natural environment conservation area where wild species of animals and plants live. On the other hand, the development pressure on the DMZ will increase when the inter-Korean economic cooperation is activated in the future. As a result, DMZ development should consider not only the economic cost-benefit aspects, but also how to assess and conserve the biodiversity of the DMZ, as well as the recovery costs and budget. This paper develope a sustainable DMZ management model under biodiversity uncertainly by using real option approach. The model is also designed to reflect the political risk and regional specificity of the DMZ. Through empirical analysis, I derive the biodiversity threshold (b^*) that can secure the DMZ investment economy under uncertainty. In addition, through the sensitivity analysis, I derive the factors influencing the biodiversity threshold, and suggest the policy implications for sustainable management of DMZ.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.05a
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• pp.788-791
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• 2010

We design 64-bit ROM IP for RFID tag chips using printed CMOS non-volatile memory IP design technology for a printed CMOS process. The proposed 64-bit ROM circuit is using ETRI's $0.8{\mu}m$ CMOS porocess, and is expected to reduce process complexity and cost of RFID tag chips compared to that using a conventional silicon fabrication based on a complex lithography process because the poly layer in a gate terminal is using printing technology of imprint process. And a BL precharge circuit and a BL sense amplifier is not required for the designed cell circuit since it is composed of a transmission gate instead of an NMOS transistor of the conventional ROM circuit. Therefore an output datum is only driven by a DOUT buffer circuit. The Operation current and layout area of the designed ROM of 64 bits with an array of 8 rows and 8 columns using $0.8{\mu}m$ ROM process is $9.86{\mu}A$ and $379.6{\times}418.7{\mu}m^2$.