• The Korean Journal of Ecology
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• 제20권4호
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• pp.285-291
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• 1997

The taxonomic characteristics of Eupatorium rugosum were reviewed and growth responses under different light intensities were investigated. Changes of soil and vegetation environments at experimental plots on Mt. Namsan were surveyed and the distribution pattern examined. The distribution of E. rugosum was closely related to the content of total nitrogen and available phosphorus in the soil. No competitors which could inhibit the growth of E. rugosum were present. Growth of E. rugosum was highest at a light intensity of 7, 500 lux, but dry weight was highest at a light intensity of 15, 000 lux followed by 30, 000 and 7, 500 lux. Growth in height of E. rugosum under a light intensity of 1, 500 lux continued even though the amount of growth was small. E. rugosum is found throughout the area of Mt. Namsan, and its density is higher at the roadside and in valley regions. E. rugosum appeared at 25 of 50 quadrats on Mt. Namsan, and the mean coverage of E. rugosum in survey quadrats was 12%.

• 천문학회지
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• 제52권5호
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• pp.181-205
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• 2019

There is evidence that the luminosities of Type Ia supernova (SN Ia) depend on their environments. While the impact of this trend on estimating cosmological parameters is widely acknowledged, the origin of this correlation is still under debate. In order to explore this problem, we first construct the YONSEI (YOnsei Nearby Supernova Evolution Investigation) SN catalog. The catalog consists of 1231 spectroscopically confirmed SNe Ia over a wide redshift range (0.01 < z < 1.37) from various SN surveys and includes light-curve fit data from two independent light-curve fitters, SALT2 and MLCS2k2. For a sample of 674 host galaxies, we use the stellar mass and the star formation rate data in Kim et al. (2018). We find that SNe Ia in low-mass and star-forming host galaxies are $0.062{\pm}0.009mag$ and $0.057{\pm}0.010mag$ fainter than those in high-mass and passive hosts, after light-curve corrections with SALT2 and MLCS2k2, respectively. When only local environments of SNe Ia (e.g., locally star-forming and locally passive) are considered, this luminosity difference increases to $0.081{\pm}0.018mag$ for SALT2 and $0.072{\pm}0.018mag$ for MLCS2k2. Considering the significant difference in the mean stellar population age between the two environments, this result suggests that the luminosity evolution of SNe Ia with redshift is most likely the origin of the environmental dependence.

• 대한위생학회:학술대회논문집
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• 대한위생학회 2004년도 심포지움
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• pp.8-27
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• 2004

본 연구에서는 가정의 여러 유해 환경 중에서도 세균과 바이러스 그리고 집먼지진드기를 효과적으로 제거할 수 있는 방법으로서 오존과 자외선이 그 대안이 될 수 있음을 실험을 통해 검증하고 있다. 실험을 통해 다음과 같은 사실이 확인되었다. 첫째, 가정과 유사한 실험 공간에서 오존과 자외선을 이용한 멸균 실험을 통해 실제 가정의 유해 세균이 수 십분 이내에 $99.0\%$ 제거되는 조건을 확인하였다. 둘째, 오존과 자외선을 이용하여 바이러스가 거되는 조건을 확인하였다. 셋째, 집먼지진드기가 제거되는 조건을 확인하였다 오존만을 적용한 조건과 오존과 자외선을 동시에 적용한 조건으로 나누어 실험한 결과를 통해 집먼지진드기는 오존과 자외선의 동시 노출 조건에서 사멸 율이 더 높게 나타났으며, 오존만을 이용한 조건만으로 집먼지진드기가 제거됨을 확인할 수 있었다.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1991년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 22-24 Oct. 1991
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• pp.652-657
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• 1991

Up to date, application areas of mobile robots have been expanded. In addition, Many types of LRF(Laser Range Finder) systems have been developed to acquire three dimensional information about unknown environments. However in real world, because of various noises (sunlight, fluorescent light), it is difficult to separate reflected laser light from these noise. To overcome the previous restriction, we have developed a new type vision system which enables a mobile robot to measure the distance to a object located 1-5 (m) ahead with an error than 2%. The separation and detection algorithm used in this system consists of pulse phase difference method and multi-stripe structured light. The effectiveness and feasibility of the proposed vision system are demonstrated by 3-D maps of detected objects and computation time analysis.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2019년도 춘계 학술논문 발표대회
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• pp.203-204
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• 2019

Recently, exposed concrete designs have been placed everywhere due to increased interest in indoor residential environments. In addition, in order to overcome the disadvantages of litracon, which was developed by mixing optical fiber, LEFC(Light Emotion Friendly Concrete) was developed in Korea, which improved unit price and constructivity by inserting hard acrylic rods. LEFC, using foaming agent and lightweight aggregate for light weighting, has disadvantages that decrease mechanical properties, and thus improved mechanical properties by using ultra-high performance concrete. Also, due to the characteristics of UHPC materials, it showed excellent self-consolidating performance. Considering these characteristics, a LEFC mold with pattern design was developed. The LEFC blocks were built so that pattern shapes could be seen and these were applied on-site to Sewoon plaza, located in Seoul.

• Corrosion Science and Technology
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• 제14권4호
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• pp.195-199
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• 2015

Materials of choice for offshore structures and the marine industry have been increasingly favoring materials that offer high strength-to-weight ratios. One of the most promising families of light-weight materials is titanium alloys, but these do have two potential Achilles' heels: (i) the passive film may not form or may be unstable in low oxygen environments, leading to rapid corrosion; and (ii) titanium is a strong hydride former, making it vulnerable to hydrogen embrittlement (cracking) at high temperatures in low oxygen environments. Unfortunately, such environments exist at deep sea well-heads; temperatures can exceed $120^{\circ}C$, and oxygen levels can drop below 1 ppm. The present study demonstrates the results of investigations into the corrosion behavior of a range of titanium alloys, including newly developed alloys containing rare earth additions for refined microstructure and added strength, in artificial seawater over the temperature range of $25^{\circ}C$ to $200^{\circ}C$. Tests include potentiodynamic polarization, crevice corrosion, and U-bend stress corrosion cracking.

• 한국항행학회논문지
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• 제16권5호
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• pp.787-793
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• 2012

64-비트 블록 암호 Piccolo-128은 무선 센서 네트워크 환경과 같이 제한된 환경에 적합하도록 설계된 경량 블록 암호이다. 본 논문에서는 Piccolo-128에 대한 biclique 공격을 제안한다. 본 논문에서 제안하는 공격은 $2^{24}$개의 선택 평문과 약 $2^{127.35}$의 계산 복잡도를 이용하여 Piccolo-128의 비밀키를 복구한다. 본 논문의 공격 결과는 Piccolo-128의 전체 라운드에 대한 첫 번째 이론적인 분석 결과이다.

• 로봇학회논문지
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• 제18권2호
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• pp.135-142
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• 2023

Light detection and ranging (LiDAR) sensors have been most widely used in terrestrial robotic applications because they can provide dense and precise measurements of the surrounding environments. However, the reliability of LiDAR measurements can considerably vary due to the different reflectivities of laser beams to the reflecting surface materials. This study presents a robust LiDAR-based mapping method for the varying laser reflectivities in indoor environments using the framework of simultaneous localization and mapping (SLAM). The proposed method can minimize the performance degradations in the SLAM accuracy by checking and discarding potentially unreliable LiDAR measurements in the SLAM front-end process. The gaps in point-cloud maps created by the proposed approach are filled by a Gaussian process regression method. Experimental results with a mobile robot platform in an indoor environment are presented to validate the effectiveness of the proposed methodology.

• 한국위성정보통신학회논문지
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• 제9권3호
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• pp.41-46
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• 2014

본 논문에서는 LED(Light Emitting Diode)의 White 조명을 이용한 VLC(Visible Light Communication) 송 수신기를 구현하였다. 가시광 통신과 다양한 환경에서 고속 데이터 전송을 위한 무선 통신 방식의 차이점을 분석하였고 QAM 전송 기법을 이용하여 실제 채널을 통과한 심벌의 수신을 확인하였다. 그리고 가시광 통신의 높은 데이터 속도를 얻기 위해 실험을 통해서 고려해야 되는 변수를 찾았다. 또한 주파수 대역을 정하고 거리에 따른 송수신간의 최적의 게인을 찾았다. 이것을 이용하여 실제 가시광 실내 환경 내에서 송수신하여 QAM 방식으로 2Mbps의 속도를 보인다.

• Journal of Ecology and Environment
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• 제35권3호
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• pp.227-234
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• 2012

Quercus aliena and Q. serrata are both occur as natural vegetation alongside natural freshwater bodies of the southern Korea Peninsula. Q. serrata dominates over Q. aliena as secondary forest vegetation in the present day. In order to explain these natural distributional traits of the oak species, we conducted some experiments with oak seedlings which treated with major important environmental resources, including light, moisture and nutrients, under controlled conditions. We then measured the ecological niche breadths and overlap from 15 eco-morphological characteristics. The ecological niche breadth of Q. aliena and Q. serrata were higher in terms of the nutrient factor applied, but was lower terms of light. The niche breadth of Q. serrata was wider than that of Q. aliena in light and moisture exposure. On the other hand, the niche breadth of Q. aliena was similar with that of Q. serrata in terms of the nutrient factor applied. These results imply that Q. serrata has a broader ecological distribution in over a wider variety of light and moisture environments than that of Q. alien. Ecological niche overlap between two oak species was the widest in terms of the light treatment factor applied, and narrowest in terms of moisture. This response pattern was also verified by cluster and principle component analysis. These results suggest competitive interactions between Q. serrata and Q. aliena seedlings may be higher for light resources than moisture or nutrient resources, and that Q. serrata is more shade tolerant than Q. aliena.