• Annual Conference on Human and Language Technology
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• 2002.10e
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• pp.85-91
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• 2002

최근 정보 추출, 질의응답 시스템 등의 고정밀 자연어처리 어플리케이션이 부각됨에 따라 개체명 인식의 중요성이 더욱 커지고 있다. 이러한 개체명 인식을 위한 학습에는 대용량의 어휘자료를 필요로 하기 때문에 충분한 학습 데이터, 즉 개체명 태그가 부착된 충분한 코퍼스가 제공되지 못하는 경우 자료희귀문제(data sparseness problem)로 인하여 목적한 효과를 내지 못하는 경우가 않다. 그러나 태그가 부착된 코퍼스를 생성하는 일은 시간과 인력이 많이 드는 힘든 작업이다. 최근 인터넷의 발전으로 웹 데이터는 그 양이 매우 많으며, 습득 또한 웹 검색 엔진을 사용해서 자동으로 모음으로써 다량의 말뭉치를 모으는 것이 매우 용이하다. 따라서 최근에는 웹을 무한한 언어자원으로 보고 웹에서 필요한 언어자원을 자동으로 뽑는 연구가 활발히 진행되고 있다. 본 연구는 이러한 연구의 첫 시도로 웹으로부터 다량의 원시(raw) 코퍼스를 얻어 개체명 태깅 학습을 위한 태그 부착 코퍼스를 자동으로 생성하고 이렇게 생성된 말뭉치를 개체면 태깅 학습에 적용하는 비교 실험을 통해 수집된 말뭉치의 유효성을 검증하고자 한다. 향후에는 자동으로 웹으로부터 개체 명 태깅 규칙과 패턴을 뽑아내어 실제 개체명 태거를 빨리 개발하여 유용하게 사용할 수 있다.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.2
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• pp.183-189
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• 2020

The purpose of this study is to investigate the compressive and tensile properties of high volume slag cement-based fiber-reinforced composite incorporating phase change material. Four mixtures were determined according to calcium hydroxide and expansive admixture, and the compressive strength and tension tests were performed. Test results showed that four mixtures showed a compressive strength over 51MPa and a tensile ductility over 3.2%. It was observed that calcium hydroxide and expansive admixture influenced the compressive and tensile performance, and the strength, ductility, and cracking patterns of composite could be improved by including proper amount of calcium hydroxide and expansive admixture.

• Transactions of Materials Processing
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• v.31 no.5
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• pp.281-289
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• 2022

Presently, 3D printers manufactured by material extrusion are economical and easy to use, so they are being used in various fields. However, this study conducted a tensile test on the infill pattern and density of the PLA+ material, due to the limitations of long printing time as well as low mechanical strength. The infill area for the infill density change was measured, using a vision-measuring machine for four infill patterns (concentric, zigzag, honeycomb, and cross) in which the nozzle path was the same for each layer. The tensile strength/weight[MPa/g] and tensile strength/printing time[MPa/min] of the tensile specimens were analyzed. In this study, efficient infill density and patterns are suggested, for cost reduction and productivity improvement. Consequently, it was confirmed that the infill area and infill percentage of the four patterns, were not constant according to the infill pattern. And the tensile strength of the infill density 40% of the honeycomb pattern and infill density 20% of the cross pattern, tended to highly consider the weight and printing time. Honeycomb and cross patterns could reduce the weight of the tensile specimen by 19.11%, 28.07%, as well as the printing time by 29.56%, 52.25%. Tensile strength was high in the order of concentric, zigzag, honeycomb, and cross patterns, considering the weight and printing time.

• Journal of the Korean Society of Clothing and Textiles
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• v.46 no.3
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• pp.481-493
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• 2022

This study investigated process conditions for 3D printing through manufacturing thermoplastic polyurethane (TPU) samples under different infill conditions. Samples were prepared using a fused deposition modeling 3D printer and TPU filament. 12 infill patterns were set (2D: grid, lines, zigzag; 3D: triangles, cubic, cubic subdivision, octet, quarter cubic; 3DF: concentric, cross 3D, cross, honeycomb), with 3 infill densities (20%, 50%, 80%). Morphology, actual time/weight and compressive properties were analyzed. In morphology: it was found that, as infill density increased, the increase rate of the number of units rose for 2D and fell for 3DF. Printing time varied with the number of nozzle movements. In the 3DF case, the number of nozzle movements increased rapidly with infill density. Sample weight increased similarly. However, where the increase rate of the number of units was low, sample weight was also low. In compressive properties: compressive stress increased with infill density and stress was high for the patterns with layers of the same shape.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.347-347
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• 2021

국내 호우 및 태풍으로 인한 홍수피해는 전체 자연재해 피해액 중 90%에 달할 정도로 심각하다. 홍수 피해는 국내의 기후적 특성으로 인해 매년 반복될 뿐만 아니라 최근엔 기후변화로 인해 강우 패턴이 변함에 따라 홍수 대응에 대한 새로운 해결책이 요구되는 상황이다. 이러한 니즈에 맞춰 국내의 홍수 관리 기술 및 제도도 빠르게 발전해왔다. 기술적으로는 수문 관측 밀도, 자료의 축적, 전송, 분석기법 등이 상당한 수준에 이르고 있다. 다만, 단기 강우 예측, 고도화된 홍수해석모형, GIS와의 연계 등이 홍수 예경보 시스템과 실무에 직접적으로 활용되기 위해서는 아직 개발기술에 대한 실용화 연구 및 적용검증이 필요하다. 뿐만 아니라, 제도적으로도 「수자원의 조사·계획 및 관리에 관한 법률 및 시행규칙」을 통해 하천구역 및 그 배후지역에서 홍수로 인명과 재산에 대한 피해가 예상될 경우 홍수 예경보를 실시하도록 하고 있다. 그러나 최근 도달시간이 짧아 홍수선행예보시간이 확보되지 못하는 경우 등이 발생하며 홍수특보 기준에 대한 보완의 필요성이 제기되고 있다. 본 연구에서는 충분한 선행예보시간 확보 및 신속한 홍수대응을 위하여 홍수발생 및 예경보 발령 사례를 분석하고자 한다. 현재 홍수특보 발령 기준은 홍수위험정도에 따라 홍수주의보 또는 홍수경보로 구분하여 발령하도록 하고 있다. 홍수위험정도의 기준은 일반적으로 수위 또는 유량을 기준으로 하고 있으며, 이를 기준수위라고 정의하여 관리하고 있다. 본 연구에서는 홍수특보지점별 사례를 통해 지점의 지형적 특성, 기준수위, 기준수위에 도달시간을 종합적으로 분석하였다. 분석결과를 바탕으로 기존의 홍수특보를 효과적으로 운영하고 홍수피해를 저감하기 위해 고려해야 할 요소를 제시하였다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2023.07a
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• pp.657-658
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• 2023

최근 건강에 대한 관심이 증가함에 따라, 다양한 식단 목표를 가진 사용자들이 맞춤형 식단 관리를 원하는 수요가 크게 증가하고 있다. 그러나 기존 식단 관리 앱들은 체중 감량이나 증량에만 집중되어 있어 사용자의 다양한 식단 목표를 충족시키지 못하는 문제점이 있다. 이러한 점을 개선하기 위해, 본 연구에서 '밀메이트'라는 개별화된 식단관리(Personalized Diet) 앱을 개발하였다. 본 앱은 사용자의 식단 목표와 선호도를 고려하여 개인화된 식단 관리를 가능하게 한다. 하루 세 끼 식사에서 벗어나 브런치 문화의 2끼 식사부터 체중 증량을 위한 4끼 이상 식사 등 다양한 식단 목표를 지원한다. 또한, 음식의 칼로리 및 주요 영양소 정보를 제공하여 사용자가 식단을 스스로 구성하고 관리할 수 있게 돕는다. 이를 통해, 체계적인 식습관 형성에 도움을 주고 다양한 식단 목표를 가진 사용자들의 필요성을 충족시키는데 기여할 것으로 기대된다.

• Korean journal of applied entomology
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• v.58 no.4
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• pp.291-297
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• 2019

Since Metcalfa pruinosa was first reported in Koera, it has continually caused damage to sweet persimmon orchard in southern part of Korea. Metcafa pruinosa exist not only in farmland but also in forest areas, and are difficult to control due to the influx of individuals from near forest. M. pruinosa has been occurred in orchard and its surroundings because of various host range. Thus, it has been difficult to decide spatial range and control time for efficient management. In this study, occurrence and dispersal pattern of M. pruinosa in persimmon orchard were surveyed using clear sticky traps, and spatial patterns were analyzed with SADIE(Spatial Analysis by Distance IndicEs), based on location information at sticky traps. Spatial association between survey time was also analyzed to identify when the spatial pattern changed. In sweet persimmon orchard, M. pruinosa mainly dispersed in mid to late May, when the first instar hatches, and in August, emerging season of adult. The first instar nymphs hatched in mid-May were randomly distributed in orchard, but distribution was changed to aggregative pattern after dispersed surroundings of orchard. Adults showed random distribution pattern after immigration to orchard again. These tendency was also observed in density change at orchard and its surroundings, and matched to actual density of M. pruinosa in sweet persimmon trees.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.4A
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• pp.352-360
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• 2008

Recently Task Group (TG) 4 of the Institute of Electrical and Electronics Engineers (IEEE) 802.15a has been recommended a system with ranging capability in existence of multiple Simultaneous operating piconets (SOPs) as well as low-cost, low-power. According to the ranging service, coherent and non-coherent based ranging schemes using ternary code have been adopted as a standard. However it is hard to estimate an accurate time of arrival (TOA) in case of using direct sequence based TOA estimation method because pulse repetition interval (PRI) offered by TG is more limited than the maximum excess delay (MED) of channel. To mitigate inter pulse interference (IPI) problem, this paper proposes a non-coherent TOA estimation scheme using non-periodic transmission (NPT) pattern. The proposed receiver is based on a non-coherent energy detection considering with motivation of low rate wireless personal area network (LR-WPAN). TOA information is estimated via proper comparison with a prescribed threshold after the sliding correlation and search back window (SBW) process for reducing TOA error. To verify the performance of proposed ranging scheme, two distinct channel models approved by IEEE 802.15.4a TG are considered. According to the simulation results, we could conclude that the proposed scheme have performed better performance than the conventional method on the existence of multiple SOPs.

• Journal of Cadastre & Land InformatiX
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• v.47 no.2
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• pp.19-37
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• 2017

Visible Infrared Imaging Radiometer Suite Day-Night Band (VIIRS-DNB) data provides a much higher capability for observing and quantifying nighttime light (NTL) brightness in comparison with Defense Meteorological Satellite-Operational Linescan System (DMSP-OLS) data. In South Korea, there is little research on the detection of NTL brightness change using VIIRS-DNB data. This study analyzed the spatial distribution and change of NTL brightness between 2013 and 2016 using VIIRS-DNB data, and detected its spatial relation with possible influencing factors using regression models. The intra-year seasonality of NTL brightness in 2016 was also studied by analyzing the deviation and change clusters, as well as the influencing factors. Results are as follows: 1) The higher value of NTL brightness in 2013 and 2016 is concentrated in Seoul and its surrounding cities, which positively correlated with population density and residential areas, economic land use, and other factors; 2) There is a decreasing trend of NTL brightness from 2013 to 2016, which is obvious in Seoul, with the change of population density and area of industrial buildings as the main influencing factors; 3) Areas in Seoul, and some surrounding areas have high deviation of the intra-year NTL brightness, and 71% of the total areas have their highest NTL brightness in January, February, October, November and December; and 4) Change of NTL brightness between summer and winter demonstrated a significantly positive relation with snow cover area change, and a slightly and significantly negative relation with albedo change.

• Korean Journal of Environmental Biology
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• v.37 no.4
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• pp.672-681
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• 2019

The ecological characteristics of Sargassum macrocarpum, an ecologically and commercially valuable brown alga, were investigated from May 2018 to June 2019 in Jeju Island, Korea. The S. macrocarpum population formed patches at depths of 3-5 m. Growth in the length of the alga reached a maximum of 135.3±20.0 cm in June. The weight of the alga reached a maximum of 3.6±2.1 kg·wet-wt in May. The mean density and biomass of S. macrocarpum was 4.5 individuals·m^-2 and 4.6 kg·wet-wt.·m^-2 in their habitat. Receptacles were observed from April to August and egg release was detected from June to July when the seawater temperatures were 19.3-22.9℃. The developmental initiation of thalli occurred at temperatures above 14.1℃ and maturation required approximately 726.3 degree-days. The reproductive allocation of this alga, calculated from the reproductive frond length(RFL) and reproductive frond weight(RFW) indices to the whole length and weight, reached a maximum of 69.3% in June. The growth and maturation patterns of S. macrocarpum could be divided into vegetative growth (October-January), maturity preparation (February-April), maturation (May-June), egg release (June-July), and resting period (August-September). This was the first study to examine an S. macrocarpum population throughout the entire year in a natural habitat in Jeju Island, Korea.