• 천문학회지
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• 제55권3호
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• pp.75-86
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• 2022

The lunar surface progressively darkens and reddens as a result of sputtering from solar wind particles and bombardment of micrometeoroids. The extent of exposure to these space weathering agents is frequently calculated as the location in a diagram of reflectance at 750 nm vs. 950 nm/750 nm color (R-C). Sim & Kim (2018) examined the R-C trends of pixels within ~3,500 craters, and revealed that the length (L) and skewness (s) of R-C trends can be employed as a secondary age or maturity indicator. We broaden this research to general lunar surface areas (3,400 tiles of 0.25° × 0.25° size) in 218 mare basalt units, whose ages have been derived from the size-frequency distribution analysis by Hiesinger et al. (2011). We discover that L and s rise with age until ~3.2 Gyr and reduce rather rapidly afterward, while the optical maturity, OMAT, reduces monotonically with time. We show that in some situations, when not only OMAT but also L and s are incorporated in the estimation utilizing 750 & 950 nm photometry, the age estimation becomes considerably more reliable. We also observed that OMAT and the lunar cratering chronology function (cumulative number of craters larger than a certain diameter as a function of time) have a relatively linear relationship.

• 상하수도학회지
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• 제18권2호
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• pp.235-241
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• 2004

The dissolved air flotation (DAF) process has been widely used for removing suspended solids with low density in water. It has been known as measuring the size of microbubbles precisely which move upward rapidly in contact zone is difficult. In this study particle counter monitoring (PCM) method is used to measure the rising microbubble after injection from a nozzle. Size and distribution curve of microbubbles are evaluated at different conditions such as pressure drop at intermediate valve, length of pipeline between saturation tank and nozzle and low pressure. And the efficiency is also checked when it collides with different size floc. The experimental results show the following fact. As the final pressure drop occurred closer to a nozzle, the bubble size became smaller. And small bubble collides with large floc as well as small one because of its physical characteristic. However large bubble collides well with large floc rather than small one since hydrodynamic flow in streamline interferes to collide between two. With performing computational process by mathematical model we have analyzed and verified the size effect between bubble and floc. Collision efficiency is the highest when P/B ratio shows in the range of 0.75 < P/B ratio ($R_{particle/Rbubble}$) < 2.0.

• 한국의류학회지
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• 제34권4호
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• pp.673-685
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• 2010

This study evaluates the fitness of brassieres through size measurement, comparative pattern analysis, cross section map analysis, 3-D shape analysis number, and fitness evaluation with a focus on domestic and overseas brands. Experimental brassieres were selected as mold brassieres of 3/4 cup in 75A size that is considered a popular design. Brands of selected brassiere were 2 domestic brands (A, B), 1 licensed brand (C), and 2 overseas brands (D, E). Subjects were 8 women in their early 20's. Data were analyzed by descriptive statistics, analysis of variance, reliability analysis, and factor analysis. The results were as follows; the size and pattern of brassieres showed a difference by each brand even though brassieres are the same design. In the wearing effect of brassieres, overseas brand brassieres played a major role in the breast-up effect, but they were not appropriate for the somatotype of Korean women. Domestic brand brassieres showed the volume-up effect, that was confirmed by the increasing bust circumference, bust depth when subjects wore it. In addition, the licensed brand brassieres showed the correction effect of body shape. Therefore, when purchasing a brassiere, the most important condition is to consider the individual characteristics of the somatotype. The results of factor analysis through a functional evaluation show that wearing satisfaction, size satisfaction, and the position of the bust point were important factors for fitness satisfaction and purchase.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2013년도 춘계학술대회
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• pp.61-62
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• 2013

본 논문에서는 마이크로스트립 선로로 급전되는 소형 광대역 평면 다이폴 안테나의 설계방법에 대해 연구하였다. 제안된 구조의 광대역 다이폴을 지상파 디지털방송 수신용으로 최적화 설계하였다. 광대역 모노폴은 특성 임피던스 75옴의 마이크로스트립 선로로 급전되고 $90mm{\times}180mm$ 크기의 FR4 기판에 설계하였다. 다이폴을 소형화하기 위해 반 보우-타이형으로 변형하였다. 마이크로스트립 선로와 다이폴을 급전하는 코프래너 스트립 간의 광대역 임피던스 정합을 위해 단순한 형태의 밸런을 이용하였다. 디지털 방송 주파수 대역인 470-806 MHz 대역에서 동작하도록 설계된 안테나를 FR4 기판 상에 제작 후 실험을 통하여 연구결과의 타당성을 검증하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.564-566
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• 2012

본 논문에서는 코프래너 도파관으로 급전되는 소형 광대역 평면 모노폴 안테나의 설계방법에 대해 연구하였다. 제안된 구조의 광대역 모노폴을 지상파 디지털방송 수신용으로 최적화 설계하였다. 광대역 모노폴은 특성 임피던스 75옴의 코프래너 도파관으로 급전되고 $100mm{\times}200mm$ 크기의 FR4 기판에 설계하였다. 모노폴을 소형화 하기 위해 슬릿을 부가하고 급전선과 모노폴의 임피던스 정합을 위해 유도성 스터브를 장하하였다. 디지털 방송 주파수 대역인 470-806 MHz 대역에서 동작하도록 설계된 안테나를 FR4 기판 상에 제작 후 실험을 통하여 연구결과의 타당성을 검증하였다.

• 한국발생생물학회지:발생과생식
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• 제25권2호
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• pp.75-82
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• 2021

We studied steroid metabolites produced from red-spotted grouper ovarian follicles during maturation. Oocytes with 350-500 ㎛ diameter were in vitro incubated in the presence of [³H] 17α-hydroxyprogesterone as a precursor. Steroid metabolites were extracted from incubated media and oocytes. The extracts were separated and identified using thin layer chromatography, high performance liquid chromatography and gas chromatography-mass spectrometry. The identified metabolites were androstenedione (A₄), testosterone (T) and estrone (E₁). The metabolites of A₄ was dominant in all size of oocytes and it was the highest in 480 ㎛ diameter oocytes. The metabolites of two progestins, 17α,20β-dihydroxy-4-pregnen-3-one and 17α,20α-dihydroxy-4-pregnen-3-one were detected in the oocytes less than 480 ㎛ diameter although they were not identified definitely. In the oocytes of 480 ㎛ diameter, metabolite of progestin was the highest, and germinal vesicle (GV) was still in the middle of cytoplasm. In the oocytes of 500 ㎛ diameter, GV was began to migrate and the major metabolites were A₄ and E₁. The metabolite of E₁ was detected in all size of oocytes and it was higher than that of E₂. These results suggest that oocytes of 480 ㎛ diameter are the transitional stage involving steroidogenic shift to final oocyte maturation and potential function of E₁ during maturation process.

• 한국전자파학회논문지
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• 제29권5호
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• pp.336-343
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• 2018

본 논문에서는 Win 사의 상용 $0.25{\mu}m$ GaAs pHEMT 공정 기술을 이용하여 X-대역(10.5~13 GHz)에서 동작하는 수신부 코아-칩의 설계 및 제작을 보였다. X-대역 코아-칩은 저잡음증폭기, 4-비트 위상천이기, 직렬-병렬 컨버터(SPC: Serial to parallel data converter)로 구성되며, 크기는 $1.75{\times}1.75mm^2$로 지금까지 보고된 코아-칩 중 가장 소형의 크기를 갖는다. 사용 주파수 대역에서 이득 및 잡음지수는 각각 10 dB 이상, 2 dB 미만, 입출력 반사손실은 10 dB 미만이다. RMS 위상 오차는 12.5 GHz에서 $5^{\circ}$ 미만, P1dB는 2 dBm으로 타 코아-칩과 대등한 성능을 갖는다. 제작된 코아칩은 조립의 편의를 제공하기 위해 $3{\times}3mm^2$ 크기를 갖는 QFN 패키지로 패키지되었으며, 패키지된 코아-칩의 성능은 칩-자체의 성능과 거의 같음을 확인하였다.

• Computers and Concrete
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• 제18권5호
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• pp.937-950
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• 2016

This study applied autoclave expansion and heat curing to accelerate the hydration of concrete and investigated how these methods affect the expansion rate, crack pattern, aggregate size effect, and expansion of electric arc furnace oxidizing slag (EOS)-containing concrete. An expansion prediction model was simulated to estimate the expansion behavior over a long period and to establish usage guidelines for EOS aggregates. The results showed that the EOS content in concrete should range between 20% and 30% depending on the construction conditions, and that coarse aggregates with a diameter of ${\geq}4.75-mm$ are not applicable to construction engineering. By comparison, aggregates with a size of 1.18-0.03 mm resulted in higher expansion rates; these aggregates can be used depending on the construction conditions. On Day 21, the prediction model attained a coefficient of determination ($R^2$) of at least 0.9.

• 한국산업융합학회 논문집
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• 제4권1호
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• pp.71-75
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• 2001

This study investigates the relationship between size of cosmetic shops, size of showcases, sorts and arrangement of light source, floor plan, and illuminance measured of interior space. From this result, the average space size of cosmetic shops were $623.2{\times}512.9{\times}258.1cm$(width, length, height), the average space size of showcases were $273.3{\times}53.8{\times}89.5cm$ (width, depth, height). The light source was most frequently used fluorescent lamp, and illuminance was the most highest nearby main showcase, and average illuminance were 722[Ix], uniformity were 0.3.

• 한국세라믹학회지
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• 제35권12호
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• pp.1280-1285
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• 1998

Foaming method is presented the preparation of porous materials from high-concentrated kaolin silica and flyash slurries. The slurries were foamed dried and sintered respectively. The porosity of sintered ma-terials was about 70-75% Mean pore-size was the range of 70-150$\mu\textrm{m}$ and pore structure was continuous Sodium lauryl sulfate anionic surfactant was used as a foaming agent. The foaming ability and the froth sta-bility were increased with increasing the concentration of the foaming agent. But the size of the constituent bubble of froth after foaming process was not affected by the concentration of the foaming agent. These results showed that the mean pore-size of sintered materials was closely related to the froth stability which is related to the change of bubble-size during the drying process.