• 한국항행학회논문지
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• 제20권5호
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• pp.425-432
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• 2016

사용자 위치 추정 시 위성 궤도는 GPS에서 송신하는 방송궤도력을 주로 이용하는데, 이를 이용할 경우 수 미터의 오차를 유발하기 때문에 높은 정확도가 필요한 분야에서는 사용할 수 없다. 오차를 유발하는 요소 중 위성 궤도와 시계에 의한 오차는 IGS에서 제공하는 RTS (real-time service)로 보정할 수 있다. 본 논문에서는 3개월간 방송궤도력과 RTS 보정정보의 궤도 및 시계 정확도를 분석하였다. IGS final을 기준으로 단일 위성과 전체 위성의 3개월간 궤도 및 시계 오차 분석을 수행하였으며, 사용자의 위치와 위성의 종류에 따른 오차 변화도 분석하였다. 그림자 조건, 태양활동, 지자기활동과 오차들과의 상관관계도 분석하였다. 보정정보에 지연시간을 적용하고 이를 다항식으로 모델링한 후 외삽하여 실제 RTS 보정정보와 궤도 및 시계정확도를 비교하였다. 방송궤도력과 RTS 보정정보가 적용된 방송궤도력으로 데이터로 PPP를 수행하고 1일 위치 추정성능을 분석하였다. 그 결과 RTS 적용 시 3D 궤도오차와 시계 오차는 방송궤도력의 1/20, 1/3 수준이었으며, 위치해의 3D 오차는 방송궤도력의 1/5 수준으로 나타났다.

• East Asian Economic Review
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• 제21권3호
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• pp.201-230
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• 2017

This paper studies the long-run behavior of relative price dispersion among cities in Korea with a special emphasis on heterogeneous transitional patterns of price level dynamics. Formal statistical tests indicate considerable evidence for rejecting the null of relative price level convergence among the majority of cities over the sample period of 1985-2015. The analysis of gravity model suggests that the effect of transportation costs on intercity price level differentials is limited, while other socioeconomic factors, such as income, input factor prices, demographic structure, and housing price growth, play key roles in accounting for persistent regional price level disparities. Individual price levels are found to be better explained by a multiple-component model, and the deviations from PPP may be attributed to distinct stochastic common trends that are characterized by income and demographic structure.

• 한국정보통신설비학회:학술대회논문집
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• 한국정보통신설비학회 2006년도 하계학술대회
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• pp.47-52
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• 2006

In this paper, we suggested new network architecture to provide seamless service between the cellular system and new wireless broadband network such as IEEE 802.16e, called WiBro. The interworking technologies are very important issue because mobile operator should provide service connectivity between various wireless networks based on different access technologies. Moreover a change and modification on legacy network should be minimized for providing interworking with new wireless broad-band network. We implemented proposed interworking architecture between 3G cellular network and 802.16e network to provide seamless service including interworking unit in real test environment. Also, we performed performance evaluation in hybrid network environments.

• Archives of Pharmacal Research
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• 제18권4호
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• pp.249-255
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• 1995

The changes in the levels of the extracellular dopamine metabolites and the responses to various dopamine agents were studied by using microdialysis inhyperglycemic rat striatum. The hyperglycemia were induced by the administriation of streptozotocin (40 mg/kg, i.p. for 3 days.). The basal levels of striatal dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) were significantly decreased in hyperglycemic rat striatum. After the administration ofl D-1 and D-2 receptor antagonists, SCH-23390 and (-)sulpiride, to rats 14 days after the last administration of STZ, the increased rates in DOPAC levels were higher in hyper- than in normoglycemic rats. However, after the administration of dopamine autoeceptor agonist, 3(-)PPP, the levels of the extracellular HVA were increased in normoglycemic rats, but those were not altered in hyperglycemic rats. The results indicate that the striatal dopamine activities were decreased in the hyperglycemic rats and suggest that release of dopamine may be decreased in hyperglycemic rats. Furthermore it suggest that the increase in the levels of the extracellular dopamine metabolites by dopamine antagonists might be dur to the incrrased sensitivities of the dopamine receptors in hyperglycemic state.

• Bulletin of the Korean Chemical Society
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• 제10권3호
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• pp.223-226
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• 1989

The chemical reactivity of 5,7-dimethoxycoumarine with adenosine has been calculated by the frontier electron and PPP-Cl MO methods. Results suggest that the major reactivity of the 5,7-dimethoxycoumarin is highest at the carbon-4 (position 4), whereas the electrophilic reactivity is generally spread all over the 5,7-dimethoxycoumarin molecule. These results are consistent with the experimental photoaddition reaction products. The small change of bond orders on excitation does not give enough reactivity to triplet states or the efficient intersystem crossing from $T_1\;to\;S_0$ inhibits photoaddition of 5,7-dimethoxycoumarine to adenosine. Although the relative intensity of the singlet band appears to be considerably higher than the triplet band intensity, its integrated intensity, i.e. oscillator strength, is comparable to that of the 5,7-dimethoxycoumarin and adenosine bands.

• Journal of Positioning, Navigation, and Timing
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• 제12권3호
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• pp.295-306
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• 2023

This paper presents a multi-frequency and multi-constellation Global Navigation Satellite System (GNSS) signal generator that simulates intermediate frequency level digital signal samples for testing GNSS receivers. GNSS signal generators are ideally suited for testing the performance of GNSS receivers and algorithms under development in the laboratory for specific user locations and environments. The proposed GNSS signal generator features a fully-reconfigurable structure with the ability to adjust signal parameters, which is beneficial to generate desired signal characteristics for multiple scenarios including multi-constellation and frequencies. Successful signal acquisition, tracking, and navigation are demonstrated on a verified Software Defined Radio (SDR) in this study. This work has implications for future studies and advances the research and development of new GNSS signals.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 1998년도 가을 학술발표회논문집
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• pp.25-28
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• 1998

Since the first report on poly(p-phenylenevinylene), the electroluminescent properties of namy conjugated polymers such as poly(p-phenylenevinylene) (PPV), poythiophene (PT), poly(p-phenylene) (PPP), and polyfluorene (PF) have been investigated because of their potential for use in display technology However, in the application of polymer light-emitting diodes (PLEDs), there are yet three fundamental issues to be considered: (1) full color capability, (2) emission efficiency, (3) stability (lifetime). (omitted)

• 전자통신동향분석
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• 제22권3호통권105호
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• pp.174-186
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• 2007

본 연구는 미국의 지방자치적 브로드밴드 사업동향을 통해 바람직한 u-City 사업의 추진에 필요한 접근방향을 살펴보고자 하였다. 즉, 미국의 추진사례를 바탕으로 우리나라에서 브로드밴드 사업 추진시 사업운영모델을 만들거나 국내 u-City에서의 적용 가능한 비즈니스 모델에 대한 시사점을 도출하고자 하는 것이다. 미국의 사례를 통해 국내u-City에 고려할 수 있는 부분으로서 민관합작(Pirvate-Public Partnership) 모형에대한 부분을 들 수 있다. 미국의 PPP 모형을 통해 지방정부는 고액의 유지보수 비용문제와 사고발생시 책임소재 문제를 해결할 수 있는 길을 마련하였다. 또한, 거주민에게는 경쟁을 통한 저렴한 가격으로 서비스를 제공하고, 저소득층과 불리한 여건의 거주자들에게 혜택을 제공함으로써 디지털 디바이드 문제를 줄일 수 있었다. 제도적인 면에서 한국과 미국이 브로드밴드 정책에 있어서 차이를 나타내고 있지만, 정책의 변화로 인해 국내에서도 지방자치적 브로드밴드 문제가 논의될 것에 대비하여 준비할 필요는 있을 것이다. 또한, 향후 직면할 문제점들을 사전에 예방하고 대비하는 데 도움이 되었으면 한다.

• 대한의생명과학회지
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• 제22권3호
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• pp.107-114
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• 2016

Maintenance of fasting blood glucose levels is important for glucose homeostasis. Disruption of feedback mechanisms are a major reason for elevations of glucose level in blood, which is a risk factor for type 2 diabetes mellitus that is mainly caused by malfunction of pancreatic beta-cell and insulin. The fasting blood glucose level has been known to be influenced by genetic and environmental factors. Mitochondria have many functions for cell survival and death: glucose metabolism, fatty acid oxidation, ATP generation, reactive oxygen species (ROS) metabolism, calcium handling, and apoptosis regulation. In addition to these functions, mitochondria change their morphology dynamically in response to multiple signals resulting in fusion and fission. In this study, we aimed to examine association between fasting blood glucose levels and variants of the genes that are reported to have functions in mitochondrial dynamics, fusion and fission, using a cohort study. A total 416 SNPs from 36 mitochondrial dynamics genes were selected to analyze the quantitative association with fasting glucose level. Among the 416 SNPs, 4 SNPs of PRKACB, 13 SNPs of PPP3CA, 6 SNPs of PARK2, and 3 SNPs of GDAP1 were significantly associated. In this study, we were able to confirm an association of mitochondrial dynamics genes with glucose levels. To our knowledge our study is the first to identify specific SNPs related to fasting blood glucose level.