• 대한화학회지
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• 제38권2호
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• pp.108-121
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• 1994

OV-1701 모세관 컬럼과 OV-1모세관 컬럼을 사용하여 컬럼온도 150, 180, $210^{\circ}C$에서 알칸, 방향족, 알코올, 아민, 케톤, 알데히드 및 고리 화합물의 머무름 지표값을 구하였다. 기능기에 의한 머무름 인자(GRF)와 구조변화에 따른 머무름 인자(SRF)는 기능기가 없는 비교 화합물로부터 계산하였다. f번째 기능기에 따른 $GRF_f$를 구하는 식은 $GRF_f\;=\;I_{obs}-(100Z +\sum\limits_{i{\neq}f}GRF_i+{\sum}SRF_i$)와 같다. 마찬가지로 f번째의 구조변화에 따른 $SRF_i$를 구하는 식은 $SRF_f\;=\;I_{obs}-(100Z + {\sum}GRFi + \sum\limits_{i{\neq}f}SRF_i$)와 같다. 계산된 머무름 지표값과 측정값과의 차이는 OV-1701컬럼에서는 ${\pm}2$, OV-1컬럼에서는 ${\pm}3$이내였다. 또한 온도변화에 따른 기능기와 구조변화에 따른 머무름 인자 $\Delta_{ xi}$와 $\Delta_{ yi}$값을 기능기가 없는 비교 화합물 로부터 계산하였다. f번째 기능기에 따른 $GRF_f$를 구하는 식은 ${\Delta}x_f$ = $\Delta'/^{\circ}C+ \sum\limits_{i{\neq}f}{\Delta}xi +{\sum}{\Delta}yi$ 와 같다. 마찬가지로 f번째의 구조변화에 따른$SRF_f$를 구하는 식은 ${\Delta}yi ={\Delta}'/^{\circ}C+{\sum}{\Delta}xi + \sum\limits_{i{\neq}f}{\Delta}yi$와 같다. 계산된 ${\Delta}xi$ 값과 측정값과의 오차는 OV-1701 컬럼에는 ${\pm}18%$, OV-1컬럼에는 ${\pm}17%$였다.

• Restorative Dentistry and Endodontics
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• 제14권2호
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• pp.1-4
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• 1989

To determine the thickness of coronal hard structure the minimal distance between pupal surface and outer surface of crown was measured by means of Bowley gauge on extracted first molars. Upper(28 teeth) and lower(24 teeth) were carefully collected from 30-39 years of age and male. The teeth were split mesio-distally through central pit. On the split surface various part which are deeply related in cavity preparation were measured (schematic drawing). The results were as follows: A : Distance from mesio-cervical enamel to pulp chamber surface. upper $2.63{\pm}0.19$(mm) Lower $2.18{\pm}0.27$(um) B : Distance from mesial chamber ceiling to mesial surface upper $2.75{\pm}0.34$ Lower $2.62{\pm}0.31$ C : Distance from mesial chamber ceiling to occlusal surface upper $3.82{\pm}0.51$ Lower $3.49{\pm}0.50$ D : Distance from distal chamber ceiling to occlusal surface upper $4.28{\pm}0.69$ Lower $3.90{\pm}0.52$ E : Distance from distal chamber ceiling to distal surface upper $2.79{\pm}0.45$ Lower $2.41{\pm}0.40$ F : Distance from disto cervical enamel to pulp chamber surface upper $2.49{\pm}0.24$ Lower $2.39{\pm}0.25$.

• 전력전자학회논문지
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• 제23권2호
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• pp.112-120
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• 2018

This work presents a hybrid generator, which is a combination of a permanent magnet (PM) and winding structure with a PM exciter. The field winding of the proposed hybrid generator is fed by the PM exciter and the embedded current controller, which is installed in the generator shaft. In the no-load condition, the output voltage of the generator is produced by the PM flux of the generator without any field winding current. The field winding current produces an insufficient flux to retain the output voltage of the generator when the load is injected. The total efficiency can be increased from the PM exciter and PM flux of the generator. The field current has to be controlled inside the proposed generator. The generated power from the PM exciter is used to excite the field flux of the generator. The embedded current controller is commanded by the external voltage controller using the infrared wireless method. The 10 kW prototype hybrid PM generator is designed and tested to verify the effectiveness of the proposed system. The experimental results are compared with those of the winding generator with PM exciter.

• 소성∙가공
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• 제33권4호
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• pp.270-276
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• 2024

In order to improve the performance of the PM (Particulate Matter) filter, the TPMS structure was used as a flow controller to control the flow entering the filter. Among various TPMS structures, a primitive structure that is easy to utilize 3D printing technique was selected and the effect of unit cell size was analyzed. In addition, numerical analysis was performed and swirl ratio was analyzed to confirm changes in filter inlet flow characteristics that affect changes in filter performance. Unit cell size is closely related to filter performance, and both PM collection efficiency and pressure drop increase as unit cell size decreases. Through quality factor (QF) comparison, which comprehensively evaluate collection efficiency and pressure drop, it was confirmed that when the unit cell size is 5 mm, PM collection efficiency increases, but the flow controller actually reduces filter performance. QF values are similar for unit cell sizes of 10 and 20 mm, and it is advantageous to select the unit cell size among these two considering collection efficiency and operating costs. The filter's collection performance increases due to the increase in swirl flow caused by the primitive structure, and the filter's collection efficiency increases due to the swirl flow that increases throughout the flow field as the unit cell size becomes smaller.

• 한국습지학회지
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• 제12권1호
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• pp.41-49
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• 2010

거미의 건축행동은 유전적 요인의 제한을 받지만 서식지의 다양한 환경 요인을 반영하는 먹이 사냥을 위한 투자 행동이며, 능동적인 의사결정의 반영이다. 본 연구는 긴호랑거미(Argiope bruennichi)를 대상으로 나대지 ('dry field')와 논습지('wet field')에 서식하는 개체가 건축한 웹의 물리적 구조를 정량적으로 측정 비교하였다. 습도 46.4%인 나대지(인천시 천마산)에서 35개체, 습도 73.9%의 논습지(충남 태안군)에서 13개체의 웹 구조가 분석되었다. 상대적으로 습도가 낮고 초본이 우거진 나대지 환경에 건축하는 개체의 경우 논습지 환경과 비교해 더 많은 거미실을 투자해($32.5{\pm}12.8$ vs. $16.9{\pm}5.4$ 개의 나선실 사용), 더 넓은 웹을 건축하였다($976{\pm}643cm^2$ vs. $532{\pm}254cm^2$). 또한 나대지에 서식하는 개체가 논습지 개체에 비해 더 높은 웹을 건축하는 것으로 나타났다($71.4{\pm}39.6cm$ vs. $49.6{\pm}31.2cm$). 흰띠줄 건축행동을 측정한 결과 나대지의 개체가 상대적으로 큰 흰띠줄을 건축하는 것으로 나타났다($18.8{\pm}3.4cm$ vs. $3.9{\pm}3.2cm$). 웹의 기울기를 측정한 수직경사와 동서경사의 경우 나대지와 논습지에서 유의미한 차이를 보이지 않았다. 본 연구 결과는 성체 암컷 긴호랑거미가 환경 요인에 따라 건축행동을 변화시킬 수 있다는 것을 시사한다

• 대한전자공학회논문지SD
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• 제45권1호
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• pp.56-63
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• 2008

본 논문에서는 WCDMA 통신용 송신기에 적용 가능한 12비트 1GS/s 전류구동 방식의 혼합형 DAC를 설계하였다. 제안된 DAC는 혼합형 구조로써 하위 4비트는 이진 가중치 구조, 중간비트와 상위비트는 4비트 온도계 디코더 구조로 12비트를 구성하였다. 제안된 DAC는 혼합형 구조에서 발생되는 지연시간에 따른 성능 저하를 개선하기 위해 지연시간보정 회로를 사용하였다. 지연시간보정 회로는 위상주파수 검출기, 전하펌프, 제어회로로 구성되어 이진 가중치 구조와 온도계 디코더 구조에서 발생하는 지연시간을 감소시킨다. 제안한 DAC는 CMOS $0.18{\mu}m$ 1-poly 6-metal n-well 공정을 사용하여 제작되었고 측정된 INL/DNL은 ${\pm}0.93LS/$ 0.62LSB 이하로 나타났다. 입력 주파수 1MHz에서 SFDR은 약 60dB로 측정되었고 SNDR은 51dB로 측정되었다. 단일 DAC의 전력소모는 46.2mW로 나타났다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.126-127
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• 2006

In this study, nano grain W is fabricated by Severe Plastic Deformation-Powder Metallurgy (SPD-PM) process. W powder and W-Re powder mixtures are processed by SPD-PM process, a Mechanical Milling (MM) process. As results, a nano grain structure, whose grain size is approximately 20nm, is obtained in W powder after MM for 360ks. A nano grain W compact, whose grain size 630nm, has excellent deformability above 1273K. A nano grain W-10Re compact is composed of equiaxed grain, a grain growth is restrained and has low dislocation density after the large deformation; therefore it is considered that W-Re compact shows superplasticity.

• 농업생명과학연구
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• 제46권4호
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• pp.57-68
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• 2012

본 연구는 관광객의 증가 및 개발로 인해 식생의 파편화가 진행되고 있는 해안 곰솔림을 대상으로 효율적인 보전과 관리를 위한 기초자료를 제공하기 위하여 곰솔 우점림에 조사구 70개($20{\times}20m$)를 설치하여 수행하였다. 경상북도 동부 해안가 곰솔림의 군집분석 결과 곰솔림은 3개의 군집(곰솔-소나무군집, 곰솔-아까시나무군집, 곰솔-소나무-팽나무군집)으로 구분되었으며, 다수응답순열절차 검정 결과, 군집은 유의성 있게 나타났다. 지표종 분석 결과, 유의한 종은 소나무, 작살나무, 노간주나무, 산철쭉 등 19종이 분석되었다. 곰솔림의 개체군 구조는 12~26 cm의 직경급이 우점하는 것으로 나타났으며 고봉형 양상(hump-shape pattern)으로 나타났다. 종다양도(H')는 목본층에서 $1.033{\pm}0.234{\sim}1.629{\pm}0.226$, 초본층에서 $2.448{\pm}0.232{\sim}2.545{\pm}0.318$ 사이로 나타났다.

• 인간식물환경학회지
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• 제22권6호
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• pp.551-561
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• 2019

This study was conducted to find out differences in the removal efficiency of particulate matter (PM) depending on the type of plants and the morphological characteristics of leaves. A total of 12 plants were used, with three plants selected for each type of leaves (big leaf, small leaf, compound leaf, needle leaf). We measured the removed amount of PM10 and PM2.5, the structure of the abaxial leaf surface, and the weight of the wax layer of each plant. Plants with the high removal efficiency of PM included Pachira aquatica Aubl., Ardisia crenata, and Dieffenbachia 'Marianne', and plants with the low removal efficiency included Nandina domestica Thunb, Schefflera arboricola, and Quercus dentata. The abaxial leaf surface having a high removal efficiency of PM had many large wrinkles, and the abaxial leaf surface having a medium removal efficiency was flat and smooth. On the other hand, there were many fine hairs on the abaxial leaf surface with a low removal efficiency. According to the plant leaf type, the PM10 removal efficiency of plants with needle leaves was about three times higher than that of other plants. In particular, the wax layer of conifers weighed 6-24 times higher than those of other plants. The stomata of conifers were evenly distributed on the adaxial and abaxial leaf surfaces; however, the stomata of Sciadopitys verticillata appeared in the form of papillae unlike general stomata. Therefore, the removal efficiency of PM varied depending on the macro-, and micro-morphological characteristics of plant leaves such as the structure of the abaxial leaf surface, and the weight of the wax layer. Based on this research, selecting plants that are effective in reducing PM in consideration of the plant type and leaf characteristics will improve indoor air quality and decrease exposure of PM to human body.

• 천문학회지
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• 제39권4호
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• pp.115-123
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• 2006

We present $JHK_S$ near-infrared CCD photometric study for the Galactic open clusters NGC 1641 and NGC 2394. These clusters have never been studied before, and we provide, for the first time the cluster parameters; reddening, distance, metallicity and age. NGC 1641 is an old open cluster with age $1.6{\pm}0.2$ Gyr, metallicity $[Fe/H]=0.0{\pm}0.2$ dex, distance modulus$(m-M)_0=10.4{\pm}0.3\;mag(d=1.2{\pm}02\;kpc)$, and reddening $E(B-V)=0.10{\pm}0.05$ mag. The parameters for the other old open cluster NGC 2394 are estimated to be $age=1.1{\pm}0.2$ Gyr, $[Fe/H]=0.0{\pm}0.2$ dex, $(m-M)_0=9.1{\pm}0.4\;mag(d=660{\pm}120\;pc)$, and $E(B-V)=0.05{\pm}0.10$ mag. The metallicities and distance values for these two old open clusters are consistent with the relation between the metallicities and the Galactocentric distances of other old open clusters. We find the metallicity gradient of 53 old open clusters including NGC 1641 and NGC 2394 to be ${\Delta}[Fe/H]/{\Delta}R_{gc}=-0.067{\pm}0.009\;dex\;kpc^{-1}$.