산악지형에서의 UHF대역 전파손실예측을 위한 LEE모델 적용방안 연구

이창원,전용찬,신임섭,김진국,Lee, Changwon,Jeon, Yongchan,Shin, Imseob,Kim, Jin-Goog 한국군사과학기술학회 2015 한국군사과학기술학회지 Vol.18 No.2

In this paper, we have compared some radio propagation models in order to verify the performance of W.C.Y LEE propagation model in mountain area. The four propagation models, which are Okumura-Hata, ITU-R P.525, Egli and W.C.Y. LEE, are analyzed by comparing the differences between measured values and propagation loss estimation values. And a correction method for W.C.Y LEE model is suggested to improve the performance of W.C.Y. LEE model with measured data in mountain area. Simulation results show that the estimation error using W.C.Y LEE model is the lowest among four propagation models. Also, the results show that the corrected W.C.Y LEE model with suggested method improves the performance of propagation loss estimation.

Purification of the Plasma Membrane and Identification of a Vanadate-Sensitive Adenosine Triphosphatase Activity in Saccharomyces cerevisiae

이창원,윤성철,김강화,Lee, Chang-Won,Yoon, Sung-Chul,Kim, Kang-Wha 생화학분자생물학회 1989 한국생화학회지 Vol.22 No.2

S. cereνisiae KCTC 1205 균주의 세포막 ATPase의 특성을 연구할 목적으로 세포막을 분리하였다. 분리과정은 세포파쇄 후 일련의 원심분리과정 (differential, sucrose density gradient)을 통하여 이루어졌으며 다량의 세포막 분리를 위한 discontinuous sucrose density gradient 원심분리조건을 구하였다. 분리된 세포막의 ATPase는 최적 pH가 5.5였으며 ATP의 농도 0.05-5mM의 범위에서 $1.3{\pm}0.4mM$의 $K_m$ 값을 나타냈다. 이 효소역가는 vanadate에 의하여 강하게 저해되었으나 oligomycin과 azide에는 비교적 무관하였다. 50%의 역가저해를 초래하는 vanadate의 농도는 $4{\mu}M$이었다. Plasma membrane was purified from Saccharomyces cerevisiae KCTC1205 in an attempt to characterize the plasma membrane $H^+$ ATPase. The purification procedure comprised disruption of cells with glass beads, differential centrifugation, continuous sucrose density gradient centrifugation (30-60%, wt/wt) and discontinuous sucrose density gradient centrifugation. The ATPase activity of the purified plasma membrane had a pH optimum of =5.5 and an apparent $K_m$ of $1.3{\pm}0.4$ mM for ATP in the substrate concentration range of 0.05-5 mM. The activity was sensitive to vanadate, while resistant to oligomycin and azide. The concentration of vanadate giving rise to 50% inhibition was determined to be $4{\mu}M$.

Characterization of the Plasma Membrane-bound ATPase of Saccharomyces cerevisiae: Dependence on $Mg^{2+}$ and Inhibition by High Substrate Concentration

이창원,Lee, Chang-Won 생화학분자생물학회 1989 한국생화학회지 Vol.22 No.2

S. cerevisiae KCTC 1205 균주로부터 분리한 세포막에 존재하는 ATPase의 특성중 $Mg^{2+}$에 대한 의존성과 고 기질농도에 의한 저해에 관하여 검토하였다. ATPase 역가는 ATP와 함께 $Mg^{2+}$ 이온이 존재할 때에만 나타났으며 Mg와 ATP의 몰비율이 1 : 1 일 때 가장 높았다. 이로써 효소의 실제 기질은 ATP 자체가 아니라 Mg와 ATP의 1 : 1 복합체임이 시사되었다. 효소의 역가는 Mg ATP의 농도가 10 mM까지 증가하다가 10 mM에서 20 mM 사이에서 급격히 감소하여 20mM Mg ATP에서는 역가가 완전히 저해되었다. 이와 같은 고 기질농도에서의 역가저해가, 기질인 Mg ATP를 $MgCl_2$와 $Na_2$ ATP로 제공할 때 첨가되는 NaCl이나 일반적으로 ATP 시약속에 미량으로 포함되어 있는 vanadate 또는 ADP에 의한 것이 아니고, 진정한 고 기질농도에 의한 저해임을 보였다. The plasma membrane-bound ATPase of Saccharomyces cerevisiae KCTC 1205 was characterized with respect to dependence on $Mg^{2+}$ and inhibition by high substrate concentration. The enzyme activity was strictly dependent on $Mg^{2+}$ as well as ATP, with a maximum activity at Mg:ATP ratio of 1:1. This suggested that the real substrate was Mg ATP complex and not free ATP. The enzyme activity increased with Mg ATP concentration up to 10 mM, followed by a rapid decrease in activity at higher substrate concentrations so that no activity was detected at 20 mM Mg ATP. It was shown that the inhibitor was Mg ATP complex itself at high concentration. Neither NaCl which was supplied as salt ions of Mg ATP $(MgCl_2+Na_2ATP)$ nor vanadate or ADP present as contaminants of the reagent ATP was the cause of the inhibition.

방산물자 원가계산체계 개선방안

이창원,Lee, Chang-Won 한국방위산업진흥회 2002 國防과 技術 Vol.- No.280

방위산업과 연계된 군수조달시장은 쌍방 독점의 형태를 가진다. 민수품에 배해 고도의 특수한 기술이 요구되는 경우가 많기 때문에 설비에 대한 높은 투자비용이 소요되게 된다. 수요자인 정부의 목표는 고품질의 방산제품을 적시에 그리고 적정한 가격으로 확보하는 것 이면에는 방산업체를 장기적으로 보호.육성해야 하는 의무도 가지고 있다. 이의 상충되는 목표를 효과적으로 조화함으로써 원가계산체계를 개선하여 적정한 원가산정이 방산업체와 정부 모두에게 가장 최선의 해결책이 될 수 있다.

Inhibition by Vanadate of the Plasma Membrane Adenosine Triphosphatase Activity of Saccharomyces cerevisiae

이창원,Lee, Chang-Won 생화학분자생물학회 1989 한국생화학회지 Vol.22 No.3

Vanadate가 S. cerevisiae KCTC 1205 균주의 세포막 ATPase 역가에 미치는 저해현상에 대하여 pH의 영향과 저해 kinetics를 조사하였다. pH 4와 9 사이에서 pH가 vanadate의 저해에 미치는 영향은 5.0 이하에서는 저해가 나타나지 않았고 5.0에서 6.5 사이에서 급격히 저해도가 증가하여 pH 8.0까지는 70-80%의 저해도가 유지되었다. 이때 최고 저해도의 1/2에 해당하는 저해도를 유발하는 pH는 5.7 부근이었다. 이로 보아 ATPase의 이온화 가능한 그룹 중 pKa 값이 5.7 정도인 그룹 (히스티딘 잔기와 같은)이 vanadate 저해에 관련할 것으로 추정되었다. 저해 kinetics의 경우, vanadate는 ATPase와 복잡한 상호작용을 하는 것으로 나타났으며, 전체적으로 uncompetitive한 성격이 지배적인 혼합형의 저해양상을 보였다. 이는 vanadate가 유리효소 자체보다는 효소반응 중간체에 주로 작용한다는 기존의 개념을 강화시키는 결과였다. The inhibition by vanadate of the plasma membrane-bound ATPase of S. cerevisiae KCTC 1205 was investigated. The inhibition was highly pH-dependent. At pH's below 5.0, there was practically no inhibition. The inhibition increased rapidly from pH 5.0 to 6.5 to reach 70-80% at pH's of 6.5-8.0. This property implied the importance of some ionizable groups(s) of pKa=5.7 (the pH of half-maximal relative inhibition) on the ATPase, possibly a histidine side chain. From the inhibition kinetics, vanadate was shown to exert a mixed type inhibition with predominantly uncompetitive character. The inhibition constants were determined by several graphical methods. Mainly uncompetitive nature of vanadate inhibition confirmed the notion that vanadate interacts with reaction intermediate(s) rather than with free enzyme.

Bridgman 법에 의한 금속급 다결정 Si 의 결정성장 및 특성평가에 관한 연구

이창원,김계수,홍준표 ( Chang Won Lee,Kye Soo Kim,Chun Pyo Hong ) 한국주조공학회 1994 한국주조공학회지 Vol.14 No.1

N/A Metallurgical-grade polycrystalline silicon was directionally solidified at growth rates of 0.2∼1.0㎜/min by using split type, reusable graphite molds which were coated with Si₃N₄powder. The resultant grain sizes of the silicon ingots and the shapes of the solid/liquid(S/L) interfaces were investigated. X-ray diffraction was used to determine the preferred orientation in each of the silicon ingots. The impurity content of the silicon was analyzed and the resistivities of the ingots were measured. During the growth of an ingot, the shape of the S/L interface was concave to the silicon melt, and the resistivity decreased. The presence of Al which can be acting as a carrier, is thought to be the main factor causing such a decrease in resistivity. When a growth rate of 0.2㎜/min was used, the preferred orientation was found to be (111).

고둥 섭취 후 발생한 일가족 테트라민 중독 1례

이창원,곽정근,박경춘,유지영,유지영,조규종,Lee, Chang-Won,Kwak, Jung-Keun,Park, Kyung-Choon,Ryu, Ji-Yeong,You, Ji-Young,Cho, Gyu-Chong 대한임상독성학회 2007 대한임상독성학회지 Vol.5 No.1

Certain parts of shellfish contain poisonous substances and cause intoxication. Tetramine toxin is found in the salivary gland of Neptunea. Three family members were admitted to the hospital with chief complaints of dizziness and blurred vision, gait disturbance, and spasms of the lower extremities after ingesting Neptunea. Physical examination revealed sluggish pupil light reflexes, but laboratory studies were normal. Symptoms were completely resolved within 24 hours after injection of atropine. We report a case of three patients with dizziness and blurred vision, gait disturbance, and spasms of the lower extremities due to Neptunea tetramine toxin.

L1014 분자운 핵에 대한 SRAO 6m 망원경을 이용한 분자선 관측연구

이창원,Lee, Chang-Won 한국천문학회 2005 天文學論叢 Vol.20 No.1

We report molecular line observations of CO(1-0), $^{13}CO(1-0)$, CS(2-1), and HCN(1-0) with SRAO 6m telescope toward L1014-IRS which is thought to be a very faint infrared source embedded in previously known 'starless' core L1014. The CO(1-0) observations find several components with different velocities along the line of sight of L1014, $4km\;s^{-1}$ and between $40{\sim}50km\;s^{-1}$. We find a parsec scale CO molecular outflow at the $4km\;s^{-1}$ component for the first time the direction of which is coincident with that of the small scale (${\sim}500pc$) outflow previously found. Although the observation is not covered for whole area of the outflow, the size of the molecular outflow seems not very inconsistent with the expected age of L1014-IRS. More accurate size and shape of the molecular outflow from L1014-IRS will be determined from the full coverage mapping in CO over the outflow region in very near future.

주류전문소매점제도 도입의 허와실(1) - 주류전문소매점 제도 도입의 기대 효과와 문제점

이창원,Lee, Chang-Won 한국주류산업협회 2001 주류산업 Vol.21 No.2

산개성단의 초기질량함수

이창원,안홍배,Lee, Chang-Won,An, Hong-Bae 한국천문학회 1987 天文學會報 Vol.12 No.-