Generation of Klobuchar Coefficients for Ionospheric Error Simulation

이창문,박관동,이상욱,하지현 한국우주과학회 2010 Journal of Astronomy and Space Sciences Vol.27 No.2

An ionospheric error simulation is needed for creating precise Global Positioning System (GPS) signal using GPS simulator. In this paper we developed Klobuchar coefficients n α and n β (n = 1, 2, 3, 4) generation algorithms for simulator and verified accuracy of the algorithm. The algorithm extract those Klobuchar coefficients from broadcast (BRDC) messages provided by International GNSS Service during three years from 2006 through 2008 and curve-fit them with sinusoidal and linear functions or constant. The generated coefficients from our developed algorithms are referred to as MODL coefficients, while those coefficients from BRDC messages are named as BRDC coefficients. The maximum correlation coefficient between MODL and BRDC coefficients was found for α 2 and the value was 0.94. On the other hand, the minimum correlation was 0.64 for the case of 1 α. We estimated vertical total electron content using the Klobuchar model with MODL coefficients, and compared the result with those from the BRDC model and global ionosphere maps. As a result, the maximum RMS was 3.92 and 7.90 TECU, respectively.

Synthesis and Characterization of Iron Oxide Nanoparticles Decorated with Carboxymethyl Curdlan

이창문,김은미,정수진,박은혜,김동욱,임석태,손명희,정환정 한국고분자학회 2009 Macromolecular Research Vol.17 No.2

Temperature-Induced Release of All-trans-Retinoic Acid Loaded in Solid Lipid Nanoparticles for Topical Delivery

이창문,정환정,박지원,김진,이기영 한국고분자학회 2008 Macromolecular Research Vol.16 No.8

The aim of this work was to develop and evaluate solid lipid nanoparticles (SLN) containing all-transretinoic acid (ATRA) for topical delivery. SLN composed of coconut oil and curdlan improved the suspension instability of ATRA in aqueous solution. The photodegradation of ATRA by light was reduced by incorporation in SLN. The loading efficiency of ATRA in SLN was higher than 95% (w/w). The amounts of ATRA released from SLN at 4 oC and at 37 oC were less than 15% and more than 60% (w/w) for 96 h, respectively. The ATRA-loaded SLN can be used as a potential carrier for topical delivery.

1LC-6 Melanin-based therapeutic agents for photothermal therapy

이창문,김민아,윤순도 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1

Photothermal therapeutic agents (PTAs) are used to help convert light to heat because of the low conversion efficiency of light energy into heat in living tissues. Melanin absorbs a large range of light from ultraviolet to near infrared (NIR) wavelengths. This presentation will discuss our recent approaches to melanin as a PTA for photothermal cancer therapy. First, we have prepared thermohydrogels containing melanin, showing sol-gel transition at body temperature. Secondly, we have prepared melanin-loaded liposomes for systemic injection. After irradiation of 808 nm NIR laser at 1.5 W/㎠ for 3 min, heat generation was enough to kill cancer cells in vitro and in vivo. The tumor growth of mice bearing CT26 tumors treated with the thermohydrogel or the liposomes is suppressed completely after laser irradiation. These results indicate that melanin can become an attractive PTA for photothermal cancer therapy.

초신속궤도력 기반 GPS 위성 repeat time 산출 및 궤도 예측

이창문,박관동,김혜인,박재민 한국측량학회 2009 한국측량학회지 Vol.27 No.4

To plan a GPS survey, they have to decide if a survey can be conducted at a specific point and time based on the predicted GPS ephemeris. In this study, to predict ephemeris, we used the repeat time of a GPS satellite. The GPS satellite repeat time was determined by analysing correlation among three-dimensional satellite coordinates provided by the 48- hour GPS ephemeris in the ultra-rapid orbits. By using the calculated repeat time and Lagrange interpolation polynomials, we predicted GPS orbits for seven days. As a result, the RMS of the maximum errors in the X, Y, and Z coordinates were 39.8 km, 39.7 km, and 19.6 km, respectively. And the maximum and average three-dimensional positional errors were 119.5 km and 48.9 km, respectively. When the maximum 3-D positioning error of 119.5 km was translated into the view angle error, the azimuth and elevation angle errors were 9.7′and 14.9′, respectively. GPS 측량 계획을 수립하기 위해서는 GPS 위성의 예측궤도력을 이용하여 측량자가 원하는 시간과 측점에 서 측량이 가능한지 여부를 판단해야 한다. 이 연구에서는 예측궤도력을 생성하기 위한 방법으로 GPS 위성 의 repeat time을 이용하였다. Repeat time은 초신속궤도력에 포함된 48시간 GPS 궤도력에서 제공하는 3차원 위성좌표의 상관관계를 분석하여 산출하였다. 그리고 계산된 repeat time을 이용하여 13차 Lagrange 보간 다 항식으로 7일간 예측 궤도를 생성하였다. 그 결과, 각 위성의 X, Y, Z 성분별 최대오차의 RMS 평균은 각각 39.8km, 39.7km, 19.6km로 나타났다. 그리고 3차원 오차의 최대값은 119.5km, 평균값은 48.9km로 나타났다. 또한 위성의 가시성 분석을 위해 3차원 최대 오차 값인 119.5km를 시야각 오차로 변환한 결과, 방위각과 고 도각의 오차는 각각 9.7′, 14.9′으로 나타났다

The Effect of Caseinate on Inclusion Complexes of γ-Cyclodextrin for Oxidative Stabilization of Fish Oil

이창문,김명희,나혜숙,김진,이기영 한국생물공학회 2013 Biotechnology and Bioprocess Engineering Vol.18 No.3

In this study, we investigated that when γ-cyclodextrin (γ-CD) forms the inclusion complexes for fish oils, the oxidation stability and retardation of odor can be effectively enhanced through the addition of sodium caseinate (SC). In order to evaluate the oxidative stability and the odor-masking effect, the inclusion complexes of γ-CD and SC incorporating fish oils at various ratios were thermally-oxidized for 5 days at a storage temperature of 55oC. The use of SC on the inclusion complexes of γ-CD could improve the oxidative stability of fish oils and the masking effect of the odor. When the inclusion complexes for fish oils were composed with 80% of γ-CD and 20% of SC, the improvement effect of the oxidative stability was better compared with the complexes of other ratios. Therefore,the use of γ-CD and SC can potentially protecting sensitive ingredients such as EPA and DHA in the food industry.

Pectin Microspheres for Oral Colon Delivery: Preparation Using Spray Drying Method and In Vitro Release of Indomethacin

이창문,김동운,이현철,이기영 한국생물공학회 2004 Biotechnology and Bioprocess Engineering Vol.9 No.3

Drug delivery systems that are based on pectin have been studied for colon specific delivery using the specific activity of colon microflora. The aim of this study was to design a novel method of manufacturing pectin microspheres without oils and surfactants and to investigate the potential use of the pectin microspheres as an oral colon-specific drug carrier. The pectin microspheres were successfully formed using the spray drying method and crosslinking with calcium chloride. From the crosslinked pectin microspheres, indomethacin (IND) release was more suppressed than its release from non-crosslinked microspheres. In a low pH (pH 1.4) environment, the pectin microspheres released IND at an amount of about 18 2% of the total loaded weight for 24 h while the release rate of IND was stimulated at neutral pH (pH 7.4). IND release from the pectin microspheres was increased by the addition of pectinase. The results clearly demonstrate that the pectin microspheres that were prepared by the spray drying and crosslinking methods are potential carriers for colon-specific drug deliveries.

DCB 적용 한반도 전리층 격자 모델 개발

이창문,김지혜,박관동 한국우주과학회 2011 한국우주과학회보 Vol.20 No.1

이 연구에서는 한반도 상공의 전리층 총전자수를 격자 형태로 나타냈다. 이를 위해 국토해양부 GPS 상시관측소에서 제공 중인 코드와 위상 측정값을 선형조합하였으며 그 결과물을 이용하여 시선방향 총전자수를 산출하였다. 이때 전리층 총전자수 산출 결과의 정확도를 향상시키기 위해 가중최소자승법을 이용하여 위성과 수신기의 하드웨어 오차인 DCB(Differencial Code Bias)를 추정하였으며 추정된 DCB값은 IGS에서 제공 중인 DCB값과 비교하여 정확도를 확인하였다. 산출된 시선방향 총전자수를 연직방향 총전자수로 변환하기 위해 사상함수를 적용하였으며, 이를 다시 각 격자점에서의 연직방향 총전자수로 변환하기 위해 기존 연직방향 총전자수에 역거리 가중 보간법을 적용하였다. 각 격자점에서의 총전자수는 IGS(International GNSS Service)에서 제공 중인 GIM(Global Ionosphere Map) 모델의 총전자수와 비교하여 정확도를 확인하였다. 산출된 총전자수는 2시간 간격으로 나타내어 한반도 상공 전리층 총전자수의 변화 경향을 확인하였다.

In vivo VEGF receptor 2-targeted imaging using TTAC-combined SPIO nanocrystals

이창문,김세림,김은미,정수진,유진산,김동욱,정환정,임석태,손명희 대한핵의학회 2007 핵의학 분자영상 Vol.41 No.5

매체환경과 청소년 사이버비행과의 관계에 대한 연구 : 성인매체몰입을 중심으로

이창문,문진영,박주원 한국디지털정책학회 2019 디지털융복합연구 Vol.17 No.4

The purpose of this study is to investigate what factors affect cyber-delinquency after examining the previous research focusing on the general strain theory and the delinquency opportunity theory in the existing studies. And as adolescents move from middle school to high school, this study is intended to analyze what factors affect cyber-delinquency from a longitudinal perspective using KCYPS(Korea Child and Youth Panel Survey) elementary 4th grade fourth and seventh data. The adolescence cyber-delinquency probability of occurrence were analyzed through the panel logit fixed-effect model using STATA. And then the cyber-delinquency frequency of adolescents were analyzed through the panel tobit random-effect model. As a result of analyzing the factors affecting cyber-delinquency frequency, Adult media commitment, computer use time, and cell phone dependency increased cyber-delinquency frequency. On the other hand, among the parenting attitudes, the attitude of supervising attentively and adolescents’ age-increasing decreased cyber-delinquency frequency. 본 연구는 사이버 비행에 영향을 미치는 요인은 무엇인지를 살펴보기 위해 기존의 여러 연구에서 검토된 일반긴장 이론, 비행기회 이론을 중심으로 선행연구를 고찰한 이후 한국 아동·청소년 패널 초등학교 4학년을 대상으로 한 패널 4차 자료와 7차 자료를 이용하여 청소년이 중학교에서 고등학교로 이행하는 과정에서 사이버 비행에 영향을 주는 요인을 종단적 측면에서 분석하고자 하였다. 연구방법은 STATA 프로그램을 이용하여 사이버 비행을 저지르는 결정요인을 패널 로짓분석을 통해 살펴본 다음 이후 패널 토빗확률효과 모형을 통하여 청소년의 사이버 비행횟수에 영향을 주는 요인들에 대해 분석하였다. 분석결과, 사이버 비행횟수와 관련해서는 성인매체몰입, 컴퓨터 사용시간, 휴대폰 의존 정도는 사이버 비행횟수를 증가시켰으며, 연령증가, 부모의 양육태도 중 관심적 감독은 청소년의 사이버 비행횟수를 감소시키는 것으로 나타났다