• Phonetics and Speech Sciences
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• v.6 no.4
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• pp.17-26
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• 2014

The present study examined epenthetic vowels produced by Korean learners of English in read sentences, in terms of acoustic measures and extra-phonological factors. The results demonstrated three main findings. First, epenthetic vowels had relatively high F1 values and a wide range of F2 values. Most of the epenthetic vowels were inserted near Korean high central vowels, but some vowels were inserted near front vowels due to co-articulation with surrounding vowels. Second, vowel epenthesis was affected by the context. The results showed that the epenthesis was frequently seen with word junctions between obstruents (e.g., stops-fricatives). Third, Korean learners were not affected by English background and were very weakly affected by orthography. English experience, which is one of the extra-phonological factors, was not related to epenthesis production. However, orthography, the other extra-phonological factor, very weakly affected the amount of epenthesis production. Nine percent of all epenthesis production was affected by the English past-tense suffix '-ed'; approximately 70% of the participants were affected by this suffix. The findings of the present study contributed to understanding vowel epenthesis. First, the study revealed that the epenthetic vowels produced by Korean learners of English were close to the high central vowel, supporting previous studies that the epenthetic vowel is quite close to the shortest vowel. Second, the study examined the various phonetic environments of epenthetic vowels, revealing that vowel epenthesis occurred more frequently in a certain phonetic circumstance.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.1444-1445
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• 2008

최근 Wireless Local Area Network(WLAN), Wide-band Code Division Multiple Access(WCDMA), CDMA2000, Bluetooth 등 다양한 모바일 통신 시스템에 대한 수요가 증가하고 있다. 이와 같은 모바일 통신 시스템에는 70dB이상의 SFDR(Spurious Free Dynamic Range)을 가진 ADC(Analog-to-Digital Converter)가 사용된다. 본 논문에서는 모바일 통신 시스템을 위한 SFDR 70dBc의 성능을 제공하는 10비트, 100Msps 파이프라인 ADC를 제안한다. 제안한 ADC는 요구되는 해상도 및 속도 사양을 만족시키기 위해 3단 파이프라인 구조를 채택하였으며, 입력단 SHA(Sample and Hold)회로에는 Nyquist 입력에서도 10비트 이상의 정확도로 신호를 샘플링하기 위해 부트스트래핑 기법 기반의 샘플링 스위치를 적용하였다. residue amplifier 회로에는 전력을 줄이기 위해 8배 residue amplifier 대신 3개의 2배 ressidue amplifier를 사용하였다. ADC의 높은 사양을 만족시키기 위해서는 높은 이득을 가지는 op-amp가 필수적이다. 제안한 ADC 는 0.18um CMOS 공정으로 설계되었으며, 100Msps의 동작 속도에서 70dBc 수준의 SFDR과 60dB 수준의 SNDR(Signal to Noise and Distortion Ratio)을 보여준다.

• Proceedings of the Korea Information Processing Society Conference
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• 2005.11a
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• pp.509-512
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• 2005

기존의 GIS 서비스는 웹상에서 제공되어 왔으나 최근 모바일 기술의 발달로 인해 모바일 단말기에서의 서비스가 가능해졌다. 하지만 모바일 단말기의 초대 장점인 휴대성에 초점이 맞춰지면서 데이터 처리 및 저장 공간의 부족, 통신 속도의 문제에 부딪히게 되었다. 또한 GIS 서비스를 위한 지리정보 표준이 없기 대문에 각 회사마다 서로 다른 형태들로 개발되어 왔으며 특정 포맷에 국한되어 자유로운 활용과 통합 및 응용이 불가하며, 각각의 데이터들을 공유하는데 많은 어려움이 있었다. 본 논문에서는 기존 지리정보포맷인 DXF(Drawing eXchange Format), SHP(SHaPefile)등을 모바일 환경에 적합하게 지리 정보를 표현함에 있어서 필요한 최소한의 속성들을 추출 및 인덱싱을 통해 경량화된 통합 DB를 구축하여 추후 OGC(Open GIS Consortium)에서 제안한 XML 기반의 표준 공간 데이터 포맷인 GML(Geographic Markup Language)로의 확장이 용이하고 좀 더 효율적인 데이터 처리 및 관리를 가능하게 한다.

• Journal of Korean Society for Geospatial Information Science
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• v.14 no.2 s.36
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• pp.55-62
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• 2006

Droughts have been an important factor in disaster management in Korea because she has been grouped into nations of lack of water. Satellite imagery can be applied to droughts monitoring because it can provide periodic data for large area for long time. This study aims to present a process to analyze droughts in large area using satellite imagery. We estimated evapotranspiration in large area using NDVI data acquired from satellite imagery. For satellite imagery, we dealt with MODIS data operated by NASA. The evapotranspiration estimated from satellite imagery was combined with precipitation data and potential evapotranspiration data to estimate water balances. Using water balances we could analyze droughts effectively in our object area. As the result of this study, we could increase the usability of satellite imagery, especially in droughts analysis.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.499-510
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• 2007

Shortest path tree(SPT) construction is essential in high performance routing in an interior network using link state protocols. When some links have new state values, SPTs may be rebuilt, but the total rebuilding of the SPT in a static way for a large computer network is not only computationally expensive, unnecessary modifications can cause routing table instability. This paper presents a new update algorithm, dynamic shortest path tree(DSPT) that is computationally economical and that maintains the unmodified nodes mostly from an old SPT to a new SPT. The proposed algorithm reduces redundancy using a dynamic update approach where an edge becomes the significant edge when it is extracted from a built edge list Q. The average number of significant edges are identified through probability analysis based on an arbitrary tree structure. An update derived from significant edges is more efficient because the DSPT algorithm neglect most other redundant edges that do not participate in the construction of a new SPT. Our complexity analysis and experimental results show that DSPT is faster than other known methods. It can also be extended to solve the SPT updating problem in a graph with negative weight edges.

• Journal of the Optical Society of Korea
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• v.19 no.5
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• pp.521-530
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• 2015

Active optics is a key technology for future large-aperture space telescopes. In the design of deformable mirrors for space applications, the design parameter trade-off between the number of regularly configured actuators and the correction capability is essential but rarely analyzed, due to the lack of design legacy. This paper presents a parametric module method for integrated modeling of deformable mirrors with regularly configured actuators. A full design parameter space is explored to evaluate the correction capability and the mass of deformable mirrors, using an autoconstructed finite-element parametric modeling method that utilizes manual finite-element meshing for complex structures. These results are used to provide design guidelines for deformable mirrors. The integrated modeling method presented here can be used for future applied optics projects.

• Proceedings of the Plant Resources Society of Korea Conference
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• 1999.10a
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• pp.58-64
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• 1999

As indicated by Chinese letters "사혁" (sha-ji) is the ripe fruit of Seabuckthron (Hippophae rhamnoides Linneus) Family Flaeagnaceae is one of ancient natural medicine used by the Tibetan and Mongolian nationallites with ancient methods to treat desease, It is an effectiv Traditional Tibetan medicine. Bud only now are they beginning to be understood in the world of modern medicine. Hippophae was written in the book of Traditional Tibetan Medicine - "Somalaza" (8th century), "Sibuyidian" (1840) and "Jingzhubencao" (Qing Dynasty). The "Sibuyidien" was trnslated in to the Russian and published at 1903 in the Russian. Then the Russian bigan to study on Hippophae and they have achieved great successes. The Chinese scientists began to study on the chemical constituent and medical action with modern technique at 1952. With more than 40 years painstaking eport they have conceived and used a wide variety of experimental screening systems, achieved successes. Finally the)1 with one's own tests has keen verified that the crude drug being various kind of bioactive substance could Inhibits tumor, increase immunity, wipe out free radical, prevent disease of cardiovascular system, have anti-radiation, anti-inflammeutory effects. At 1977 the Hippophae rhamnoides was written in Chinase Pharmacopoeia.e rhamnoides was written in Chinase Pharmacopoeia.

• The Magazine of the IEIE
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• v.29 no.11
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• pp.1333-1342
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• 2002

최근 들어 컴퓨터 통신의 확산과 함께 인터넷의 사용이 전 세계적으로 급증함에 따라 인터넷의 용도는 지금까지의 학술 및 연구를 대상으로한 정보 공유의 목적에서 인터넷을 마케팅의 대상으로 보고 이를 상업적으로 이용하려는 시도가 증가하고 있다. 이미 선진 외국의 경우에는 Mon-dex, Visa cash, Proton 등의 다양한 전자화폐 상품이 개발되어 사용되고 있으나 국제 호환성의 측면에서는 아직 미미한 형편이며 국제간 통용이 가능한 개방형 전자화폐 시스템 개발은 매우 필요하다. 소액지불 시스템의 국제 표준규격으로 인정받고 있는 CEPS(Common Electronic Purse Specification) 기반의 개방형 전자화폐 teem 시스템은 EMV(Europay, Master, Visa) 규격을 준용하고, PKI 기반의 보안기능을 채택하여 지불거래시 반드시 확보되어야 할 거래 데이타의 비밀성, 무결성, 부인방지 기능과 PIN(Personal Identification Number)를 이용한 사용자 인증을 제공하며 구매거래시 IC카드와 가맹점의 구매 단말기(POS)와의 오프라인 동적데이타 인증 (Dynamic Data Authentication) 방식의 상호인증을 제공한다. 개방형 전자화폐 teem 시스템의 구성 모듈은 발급, 충전, 구매, 정산, 인증시스템으로 구성되어 있으며, 웹기반의 사용자 인터페이스를 제공하고 DES, 3-DES, SHA-1, RSA, SEED등 다양한 암호 모듈과 다양한 어플리케이션의 탐재가 가능한 Java Card를 기반으로 하고 있으며, VOP(Visa Open Platform) 2.0,1, Java Card API 2.1 지원하는 시스템이다.

• Phonetics and Speech Sciences
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• v.6 no.2
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• pp.163-174
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• 2014

Korean L2 speakers have many problems learning the pronunciation of English words. One of these problems is vowel epenthesis. Vowel epenthesis is the insertion of vowels into or between words, and Korean learners of English typically do this between successive consonants, either within clusters, or across syllables, word boundaries or following final coda consonants. The aim of this study was to investigate whether individual differences in vowel epenthesis are more closely related to the perception and production of segments (vowels and consonants) and prosody or if they are relatively independent from these processes. Subjects completed a battery of production and perception tasks. They read sentences, identified vowels and consonants, read target words likely to have epenthetic vowels (e.g., abduction) and demonstrated stress recognition and epenthetic vowel perception. The results revealed that Korean second-language learners (L2) have problems with vowel epenthesis in production and perception, but production and perception abilities were not correlated with one another. Vowel epenthesis was strongly related to vowel production and perception, suggesting that problems with segments may be combined with L1 phonotactics to produce epenthesis.

• Advances in environmental research
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• v.4 no.1
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• pp.49-68
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• 2015

Chemically activated and carbonized adsorbents were prepared from Moringa oleifera pod husks (MOP), characterized and evaluated for their ability to remove a common antibiotic - ofloxacin (OFX) from aqueous solution. The pulverized precursor was steeped in a saturated ammonium chloride solution for a day to give the chemically activated adsorbent (AMOP). A portion of AMOP was pyrolyzed in a muffle furnace at 623 K for 30 min to furnish its carbonized analogue (CMOP). The adsorbents showed favorable physicochemical attributes. The effects of operational parameters such as initial OFX solution pH and concentration, adsorbent dosage, temperature and contact time on OFX removal were investigated. At equilibrium, optimal removal efficiencies of 90.98% and 99.84% were achieved at solution pH 5 for AMOP and CMOP, respectively. The equilibrium adsorption data fitted into both the Langmuir and Freundlich isotherms. Gibbs free energy change (${\Delta}G^o$), enthalpy change (${\Delta}H^o$) and entropy change (${\Delta}S^o$) indicated that the adsorption of OFX was feasible, spontaneous, exothermic and occurred via the physisorption mode. Adsorption kinetics obeyed the Blanchard pseudo-second-order model. The results may find applications in the adsorptive removal of micro-contaminants of pharmaceutical origin from wastewater.