• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.474-477
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• 2002

Information technology has affected various industries, and the construction industry is one of those. In construction industry, the operating body for maintenance is trying to implement more systematic management skill for public facilities in order to minimize the life cycle cost. For more efficient maintenance system, first, the target facilities were selected and the present condition of their systems was estimated. And, the implementation plan of new system was proposed based on them. Accordingly, the new system managed by working-level personnel can supplement the weak points in the current system.

• Proceedings of the KSAR Conference
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• 2003.06a
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• pp.89-89
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• 2003

본 연구는 난소의 황체를 체외배양시 TGF-$\beta$1의 황체내 발현을 조사하기 위해 수행되었다. 돼지 황체는 축산기술연구소에서 사육중인 돼지(체중 145$\pm$kg) 12두로부터 발정을 유도시켜 배란 후 약 48시간째 도축하여 난소를 회수하였다. 회수된 난소로부터 황체를 분리하여 세절한 후 0.25% collagenase용액(0.025mg DNase, 50mM EDTA, 50mM Dithio-threitol)으로 37$^{\circ}C$의 진탕 수조에서 30분간 배양하여 황체세포를 분리 회수하였다. 회수된 황체세포는 D-MEM용액(GIBCO, 10% FCS와 antibiotics 첨가)으로 2회 세척하여 1$\times$$10^{6}$live cell/$m\ell$이 되도록 희석하여 24 well culture plate(Corning, New Tork 14831)에 분주하여 $CO_2$ 배양기($CO_2$: 5%)에서 24시간 간격으로 2회 배양액을 교환해 48시간 동안 배양하였다. 배양된 황체 세포는 immunocytochemistry 방법으로 TGF-$\beta$1의 발현을 관찰함과 동시에 황체조직도 같은 방법을 사용하여 TGF-$\beta$1 의 발현 유ㆍ무을 관찰하였다. 그 결과 황체세포 그리고 황체 조직 뚜렷한 TGF$\beta$1의 발현을 확인할 수 있었다. 이 결과로서 TGF$\beta$1은 황체기능을 유지하는데 하나의 인자로서 작용하며 다른 인자들과의 상호작용을 시사하고 있다.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.5
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• pp.863-871
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• 2003

In this paper, we design a high stable Ku-band phase-locked dielectric resonant microwave oscillator with the gate voltage controls of p-HEMT. By adapting the nonlinear equivalent elements which affects phase noise of microwave oscillator, we optimize the nonlinear elements of p-HEMT to have low phase noise operation. Using the scattering parameters according to bias voltages, we designed the gate voltage control microwave dielectric resonant oscillator and phase-locked loop circuits is applied to have the high stable operations. Designed microwave oscillator as a local oscillator of digital microwave communication shows that output power is 9.17dBm at 10.75GHz and it's phase noise is -88dBc/Hz at 10KHz offset frequency.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.8
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• pp.1297-1304
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• 2002

The phase locked oscillator having a low phase noise and high output in Ku-band was designed. To obtain the low phase noise and high output characteristics of oscillator, the nonlinear equivalent circuits of p-HEMT was analyzed by TOM method and we have decided the trade-off bias point between the low phase noise and the output power of oscillator. The designed phase locked oscillator with prescaler for stable operation, experiment results exhibits output power of 1003m with phase noise in the phase locked state of -824BC/HB at 10mz offset from 13.250Hz, and simulation result of 1003m output power in the phase noise -840Bc/Hz at 10KHz offset frequency respectively. a good agreement has been obtained between simulations and experiments results.

• Journal of IKEEE
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• v.17 no.4
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• pp.537-543
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• 2013

This paper proposed a low EMI spread spectrum clock generator (SSCG) using discontinuous frequency modulation technique. The proposed SSCG is designed for triangular frequency modulation with high modulation depth. When the maximum time interval error (MTIE) of the SSCG is higher than given limit, the output frequency of SSCG is divided by two and used for reducing the time interval error (TIE). This discontinuous frequency modulation technique can effectively reduce the EMI within given limit. The simulated EMI of proposed SSCG was reduced by 18.5dB than that of conventional methods.

• Journal of Life Science
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• v.12 no.5
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• pp.570-576
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• 2002

The extremely halophilic archaebacterium Haloarcular sp. EH-1 was isolated from solar salts. Amylae production from Halonrcular sp. EH-1 have been studied. The results obtained were as follows. The optimal medium composition for the production of amylase from Haloarcular sp. EH-1 were soluble starch 1.5%, yeast extract 1.0%, MgSO$_4$ 7h$_2$O 2.0%, KCI 0.1%, NaCl 25% (pH 7.5). The incubation temperature, aeration rate and agitation speed were 4$0^{\circ}C$, 100 $m\ell$ medium / 500 $m\ell$ shaking flask, and 110 rpm. The cell growth and enzymatic activity was highest at 9 days of incubation. So amylase production appeared to be a growth-related phenomenon.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.4 no.2 s.7
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• pp.73-79
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• 2005

Various CMOS quadrature-voltage-controlled oscillators(QVCOS) are designed and fabricated for the comparison of the phase noise characteristic. The first one is that the QVCO is composed of two Colpitts oscillators cross-coupled with PMOS coupling transistors. The second and third ones are the conventional LC VCO and the balanced Colpitts VCO followed by the frequency-divide-by-two, respectively. The simulation result demonstrate that Colpitts schemes show better phase noise performance by 6 dB than that of a conventional stheme in which LC VCO is followed by the frequency-divide-by-two.

• Journal of the KSME
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• v.19 no.4
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• pp.273-278
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• 1979

화학적 가공이란 화학적 절식이라고 말할 수 있는 방법으로서 주조 또는 공작기계에 의한 절삭 가공대신에 약품에 의한 용해작용을 이용해서 성형품을 만드는 방법이라 할 수 있다. 이 방법은 금속자의 눈금의 조각이나 프라스틱 제품에 눈금을 넣는 금형등에 이용되고 있다. 이는 원래 항공기공업방면에서 중용되어 개발된 기계가공에 대응하는 방법이다. 크기나 정밀도에 있어서 주조(die casting)가 부적당한 경우 혹은 모양이나 능률에 있어서 기계절삭에 의하는 것이 부적 당한 경우에는 이 방법이 이용된다. 최근에 와서는 항공기기계제작 분야에 있어서의 알루미늄의 표면가공뿐만 아니라, 자동차, 건축부분의 구조부품의 성형분야에도 진출하는 경향이 있으며 가 공대상금속도 실용금속일반에 걸쳐 확대되어 감으로써 가장 용도가 넓은 철강류에 확대되어 감 으로써 가장 용도가 넓은 철강류에 까지도 응용되어 가는 실정이다. 이와 같이 종래의 기계적인 수단이 유일한 방법이라고 생각되었던 금속가공분야에 있어서 이러한 화학적 가공법이 도입되 었다는 것은 십분주목할만 한 가치가 있다. 이 화학적 가공법의 특징을 종래의 기계가공법과 비교하면 다음과 같다. (1) 피가공판의 크기는 이를 수용하는 가공조의 용량에 따라 제한될뿐이며 어떠한 대형 물이라도 가공 가능하다. (2) 가공모양은 자유롭게 설계할 수 있고 더욱이 1매 금속 판에서 1공정으로서 복잡한 모양으로 성형할 수 있다. (3) 따라서 이작업에서는 리벳팅, 용접등의 부대작업을 필요로 하지 않는다. (4) 그 가공면은 일반으로 평활하고 마루리 연마공정을 생략할 수 있다. (5) 가공조작이 간편하여 특별한 숙련을 요하지 않고 설비도 가공조의에는 별로 고가의 기기류가 필요치 않다. (6) 이상과 같은 이유에서 본법의 가공비는 기계가공에 비해서 일반적으로 저렴하다. Symposium보고및 전문서가 많이 있으나 여기에는 중요한 몇가지만 소개한다.

• Journal of Advanced Navigation Technology
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• v.2 no.1
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• pp.22-33
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• 1998

In the coherent-on-receiver radar system using the magnetron source, frequency synthesizer is employed as a STALO(Stable Local Oscillator) to keep the intermediate frequency stable. In this paper, X-band(8.4GHz~9.7GHz) single loop frequency synthesizer is designed and implemented by an indirect frequency synthesis technique. Phase comparison is performed by a digital PLL(Phase-Locked Loop) chip and the loop filter is designed for the low phase noise. The effects of loop component characteristics on the output phase noise are analyzed for single loop structures, and the calculated results are compared with the measured data.

• Korean Journal of Plant Tissue Culture
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• v.26 no.3
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• pp.157-161
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• 1999

This study was performed to enhance the proliferation rate of Gladiolus 'Topaz' callus. The callus was induced from the cermet tissue explants on MS solid medium with 10 mg/L 2,4-D. In the case of liquid shaking culture, proliferation of the callus was effective in MS medium with 0.05 mg/L 2,4-D at 2$0^{\circ}C$ under 16 hours daylength and in a 100 mL Erlenmeyer flask containing 20 mL of the liquid medium and at 75 rpm in rotation speed of the horizontal shaking culture. Furthermore the callus was also able to be subcultured in the same liquid medium.