• Electronics and Telecommunications Trends
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• v.23 no.1 s.109
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• pp.99-108
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• 2008

3G LTE 이동통신 시스템은 패킷 데이터 전송에 기반을 둔 다양한 서비스 지원을 목표로 하는 기술로서 최대 20MHz 대역폭 기준 하향링크 최대 전송속도 100Mbps, 상향 링크 50Mbps의 전송속도를 지원한다. 그리고 데이터 전송 효율 향상, 효율적인 주파수 자원 이용, 이동성, 낮은 latency, 패킷 데이터 전송에 최적화된 기술과 서비스 품질보장 등을 제공한다. 3G LTE 시스템은 기존 시스템에 비해 주파수 및 고속의 멀티미디어 서비스를 효율적으로 사용하는 IP 네트워크로 진화되는 이동통신 시스템이다. 3G LTE 이동통신 단말은 대역폭 20MHz 기준으로 이동속도 120km/h에서 하향링크 30 Mbps, 상향링크 15Mbps의 데이터 전송속도를 지원한다. 또한, 고품질 및 고속의 멀티미디어 서비스를 제공하는 단말로서 3.5세대인 HSDPA에 반해 모바일 영상 서비스가 본격적으로 제공되는 3G LTE 이동통신 시스템의 단말이다. 본 고에서는 3G LTE 이동통신 시스템 단말 플랫폼 기술 동향과 전망에 대하여 논의한다. II장에서는 3G LTE 표준 규격을 기반으로 구현하는 3G LTE 이동통신 시스템 및 단말 플랫폼을 서술하며, III장에서는 국ㆍ내외 단말 플랫폼 기술 동향에 관한 내용을 기술한다. IV장에서는 향후 발전 전망에 대해 살펴보고, 마지막으로 결론을 맺고자 한다.

• BMB Reports
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• v.31 no.3
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• pp.209-220
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• 1998

How did nature create the first set of genes at the beginning of life on Earth? One of the goals of molecular biology is to elucidate the fundamental rules governing how genes and, therefore, proteins were created. Through experiments carried out in the emerging field of "in vitro" or "benchtop" evolution studies, we are gaining new insights into the origins of genes and proteins as well as the origins of their functions (e.g., catalysis). In this review, I present an overview of recent experimental approaches to the question of the origin and evolution of genes. In addition, I will introduce a novel in vitro protein emergence system that was recently developed in my laboratory.

• Journal of The Korean Association For Science Education
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• v.36 no.3
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• pp.509-517
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• 2016

Previous studies have investigated the similarity between the development of evolutionary explanations and students' conceptual developments on evolution. However, the validity and reliability of the assessment method reflecting the similarity have not been quantitatively examined yet. In addition, no study has examined the conceptual progressions of evolution concept based on contexts although literature has addressed the contextual difference of evolutionary explanation in the history of science. This study examined the validity and reliability of history-of-science-based evolution concept assessment using ordered multiple choice (OMC) methods and Rasch analysis and explored conceptual progression by three contexts (e.g., human, animal, and plant). The evolution concept assessment developed by Ha (2007) was used to examine 1711 elementary, middle, and high school students, and pre- and in-service science teachers' (biology majors and non-majors) evolution concepts. Internal consistency reliability and item response fitness of the OMC method that provide 0- to 4-point scores to creationism, teleology, intentionality, use/disuse, and natural selection respectively met the benchmark based on the Cronbach alpha and MNSQ indices of Rasch analysis. The level of elementary and middle school students' evolution concepts were located between intentionality and use/disuse while the level of high school and non-biology science teachers' evolution concepts were located between use/disuse and natural selection. The conceptual progressions of evolution concepts were differentiated according to three contexts. This study provided the quantitative evidence for the similarity between the development of evolutionary explanations and students' conceptual developments on evolution and suggest new analysis methods (i.e., OMC) of evolution concept assessment.

• Animal Systematics, Evolution and Diversity
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• v.18 no.1
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• pp.99-120
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• 2002

Three species of the family Gynodiastylidae, Gynodiastylis anguicephala Harada, 1962, G. tubicola Harada, 1962 and G. rotundicaudata Gamo, 1961 are recorded newly to Korean fauna. New information on the mouthparts of these species is given, and the male of G. rotundicaudatus is described for the first time.

• Information and Communications Magazine
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• v.23 no.6
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• pp.19-28
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• 2006

보다 높은 기술적 요구사항을 지니는 차세대 통신 시스템의 무선 접속 기술은 직교 다중파 전송 방식(OFDM)과 다중안테나 기술로 특징 지워진다. 현재 전세계적으로 고속 광대역 접속을 위한 이런 핵심 기술들은 IEEE 802.16,20, 3GPP, 3GPP2와 같은 국제 표준단체에서 표준 기술로 보편적으로 고려되고 있다. 다양한 표준 단체에서 경쟁적으로 차세대 이동 통신 표준 시스템을 개발함에도 불구하고, 3GPP LTE(Long Term Evolution) 시스템은 전세계적인 통신 기반환경과 일관된 시스템 진화과정을 고려 할때 가장 주목 받는 시스템으로 부각되고 있다. 본 논문에서는 차세대 통신 시스템의 실현 기술에 대한 기술적 정당성과 향후 차세대 통신 시스템의 한축을 이루게 될 3GPP LTE의 표준 동향 및 전망에 대해 알아본다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.204-205
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• 2013

최근 일본의 지진 쓰나미 등 전 세계적으로 많은 재난이 증가하고 있고, 국내에서는 신속한 재난 정보 전송을 위해서 CBS(Cell Broadcast Service) Alert Message를 국가 표준으로 제정하였다. CBS를 통한 전송은 지역단위 전송이 가능하므로 재난이 발생한 지역에 신속한 전송 서비스를 가능하게 해준다. 하지만 국내의 경우 CBS Alert Message가 LTE(Long Term Evolution) 단말에서만 수신이 가능하고 3G 단말에서는 수신이 불가능하다. 이에 본 논문은 실내 환경에서 gateway-AP(Access Point)를 이용하여 3G 단말이 CBS Alert Message를 수신 할 수 있는 방법을 제시하려고 한다.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.238-244
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• 2005

Fertilization effects on changes in soil $CO_2$ flux and organic C in switchgrass (Panicum virgatum L.) land managed for biomass production were investigated. The mean daily soil $CO_2$ flux in the manure treatment was 5.63 g $CO_2-C\;m^{-2}\;d^{-1}$, and this was significantly higher than the mean value of 3.36 g $CO_2-C\;m^{-2}\;d^{-1}$ in the control. The mean daily $CO_2$ fluxes in N and P fertilizer treatments plots were not different when compared to the value in the control plots. Potentially mineralizable C (PMC), soil microbial biomass C (SMBC), and particulate organic C (POC) were highest at the 0 to 10 cm depth of the manure treatment. Potentially mineralizable C had the strongest correlation with SMBC (r = 0.91) and POC (r = 0.84). There was also a strong correlation between SMBC and POC (r = 0.90). Our results indicated that for the N and P levels studied, fertilization had no impact on temporal changes in soil organic C, but manure application had a significant impact on temporal changes in soil $CO_2$ evolution and active C constituents such as PMC, SMBC, and POC.

• Geomechanics and Engineering
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• v.20 no.2
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• pp.165-174
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• 2020

The enzyme-induced carbonate precipitation (EICP) method has been investigated to improve the hydro-mechanical properties of natural soil deposits. This study was conducted to explore the stiffness evolution during various stress scenarios. First, the optimal concentration of urea, CaCl₂, and urease for the maximum efficiency of calcite precipitation was identified. The results show that the optimal recipe is 0.5 g/L and 0.9 g/L of urease for 0.5 M CaCl₂ and 1 M CaCl₂ solutions with a urea-CaCl₂ molar ratio of 1.5. The shear stiffness of EICP-treated sands remains constant up to debonding stresses, and further loading induces the reduction of S-wave velocity. It was also found that the debonding stress at which stiffness loss occurs depends on the void ratio, not on cementation solution. Repeated loading-unloading deteriorates the bonding quality, thereby reducing the debonding stress. Scanning electron microscopy and X-ray images reveal that higher concentrations of CaCl₂ solution facilitate heterogeneous nucleation to form larger CaCO₃ nodules and 11-12 % of CaCO₃ forms at the interparticle contact as the main contributor to the evolution of shear stiffness.

• The Bulletin of The Korean Astronomical Society
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• v.42 no.1
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• pp.49.3-50
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• 2017

Metallicity is one of the most important properties in understanding galaxy evolution. However, measuring metallicity is limited to low redshift (z<3.5) due to the faintness of the metallicity indicators in normal galaxies. For high redshift universe, active galactic nuclei (AGN) can be used to constrain the host galaxy metallicity. Previous studies investigated AGN metallicity using emission line flux ratios (i.e., NV/CIV and FeII/MgII), finding no evolution up to z~6. Those results might be due to selection effect since previous studies are based on very luminous AGNs. The observed luminosity-metallicity relation of AGNs (e.g., Nagao et al. 2006) suggests that luminous AGNs may be already matured at the observed epoch. Considering the luminosity-metallicty relation, we focused on low luminosity AGNs to find young AGNs (i.e., low metallicity). Through the Gemini/GNIRS observation in 2012A and 2015A (K-GMT GN-2015A-Q-203 PI: Shin, J.), we obtained the Gemini/GNIRS data for 7 high redshift AGNs (3.0

• Transactions of the Korean hydrogen and new energy society
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• v.4 no.2
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• pp.5-15
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• 1993

Hydrogen production in visible light with the following semiconductor systems, $CdS-WO_3$, $CdS-TiO_2$, have been investigated in the presence of redox catalyst (Pt, $RuO_2$). MeOH, EtOH, isopropanol, sulfide/sulfite mixture, lactic acid were used as sacrifical reagents. The optimal condition for $H_2$ evolution was found to be in qgueous lactic acid media for $CdS-WO_3/RuO_2$. The photochemical efficiency for this system was 1.05 % and the $H_2$ evolution rate was 26.5ml/min. at $6.07{\times}10^{-5}$ einstein/sec photon rate