• 대한전자공학회논문지
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• 제20권1호
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• pp.22-26
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• 1983

열확산(thermal diffusion)법을 이용하여 면적이 3.36㎠인 P+N 전지와 P+NN+ 전지를 제작하였다. 100mW/㎠의 인공 조명에서 측정한 결과 940℃에서 15분 보론확산(boron Predeposition)을 하고, 800℃에서 20분 열처리(annealing)하여 제작한 P+N전지는 전면적(수광면적) 변환 효율이 13.4%(14.7%)이었다. 뒷면을 1050℃에서 인(Phosphorus)을 확산한 후, 앞면을 940℃에서 15분 보론 확산하고, 800℃에서 50분 열처리하여 만든 P+NN+전지의 전면적(수광면적) 변환 효율은 14.3%(15.6%)이었다. 뒷면의 인 확산으로 게더링(gettering) 작용과 BSF 효과에 의해서 P+NN+ 전지가 P+N전지보다 캐리어 수명이 약 2∼3배 증가되었다. 그리고 효율 개선을 위해 AR로팅, Ag전기도금, 미세한 그리드 패턴, 앞면 불순물 주입량 조절 등을 행하였다.

• 한국환경보건학회지
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• 제31권6호
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• pp.475-482
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• 2005

This study aimed to determine the fluoride intakes in 120 preschool children aged 3 to 6 residing in Jumunjin (community water fluoridation area) and Gangneung (non-fluoridation area). The parents were asked to collect 24-hour urine samples and to duplicate the samples of all the diets that their children ingested in the day of urine collection. The acid-diffusible fluoride in the food and non-carbonate beverages were isolated by the acid-diffusion technique and then measured with a fluoride electrode. The fluoride in carbonate beverages, drinking waters and urine samples were measured directly with a fluoride electrode. The geometric mean (geometric standard deviation) of daily fluoride intakes from all kinds of diet was 5.99 (2.27) $\mu$g/kg/day in the children in Gangneung and that of the children in Jumunjin was 18.36 (2.69). The amount of fluoride intake by food and drinking water in fluoridation area were significantly larger than that in non-fluoridation area but the statistical difference of fluoride intake by beverages between two areas was not observed. The GMs (GSDs) of daily fluoride excretion by urine of children in non-fluoridation area and in fluoridation area were 8.39 (1.73) and 18.62 (1.77) $\mu$g/kg/day, respectively. The correlation between fluoride intake from diet excluding beverage and urinary excretion was statistically significant. It is concluded that the amount of fluoride intake of children living in fluoridation area did not exceed the upper intake level to avoid the risk of dental fluorosis (2.2 mg/day in 4- to 8-year-olds) and urinary excretion of fluoride was good indicator of fluoride intake from diets.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2016년도 추계 학술논문 발표대회
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• pp.148-149
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• 2016

In this paper, the increase in chloride resistance of footing concrete at coastal area was evaluated by replacement of Mineral Admixture. In KBC 2009, the footing concrete's minimum specific concrete strength at coastal area is determined to 35MPa. However, this is criteria only based on the strength aspect. Thus, it is not considered to increase the chloride resistance by replacement of Mineral Admixture. According to the test results of chloride ions penetration resistance, 35MPa class concrete with OPC 100% shown inaccessible state. Low-strength (24~30MPa class) concretes with Mineral Admixture, however, presented better performances. In addition, chloride diffusion coefficient tests showed identical appearance. Therefore, the current KBC's chloride resistance criteria based on only concrete strength has to review for the reason it can cause many problems (ex. cost increases by growing concrete strength and the environmental issues by a lot of cement use).

• Animal cells and systems
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• 제8권2호
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• pp.111-115
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• 2004

The epidermis of the mudskipper, Periophthalmus modestus, consists of three layers- the outermost layer, middle layer and stratum germinativum. Extensive fine blood capillaries are present near the superficial layer of epidermis and outermost layer in five fins and a sucking disc. The diffusion distance between the vascular capillaries and the surface of epidermis ranged from 3.6 to 10.9${\mu}$m: 3.6 ${\mu}$m in the sucking disc, 10.9 ${\mu}$m in the anal fin and 4.6 to 5.0 ${\mu}$m in the two dorsal fins. Rate of the surface area of respiratory epithelium, the surface area of the fine blood capillaries occupied per surface area of epidermis in 0.1mm, is 3.7 to 4.4% in two dorsal fins and 1.1% in the anal fin. The middle layer is simpler in structure consisting of small or voluminous cells swollen by epidermal cells, and this layer appeared web-like. Well-developed lymphatic spaces containing lymphocytes existed in the stratum germinativum. The five fins and sucking disc had no epidermal glands.

• 한국농공학회지
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• 제42권3호
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• pp.5-17
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• 2000

The story of route of wet-rice diffusion to Korean peninsular is so far known only piecemeal. It is however commonly agreed that wet-rice technology may have spread the western coastal area in Korea from the lower and middle reaches of the yangzi river in China and to the Shandong peninsular and Bohai Bay region and was then transmitted overland to the area in Korea. Recently excavated three prehistoric paddy fields in Korea provide crucial evidence that helps to solve many of the important problems associated with technological diffusion. Research on the paddy field system and irrigation technology of prehistoric wet-rice has been so far especially productive in Japanese archaeology. Judging from the fact that the Yayoi wet-rice agricultural technology in Japan was transmitted by the Korean Strait from the southern part of Korea it is assumed that people in both regions may have practiced the same technology in prehistoric time. This paper examines three prehistoric paddy fields system(the Majon-ri site the Kwanchang-ri site and the Mujon-dong site) in relation to those of japanese data. The conclusions are as follows ; First early wet-rice agriculture in korea was limited by the level of technology and the size of labour. Secondly the location of field itself was restricted to the lower land and valley bottom area. Thirdly the layout of channel and field network is not very much different from the modern paddy field system.

• 한국통신학회논문지
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• 제35권4C호
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• pp.408-414
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• 2010

CCTV이미지에서 교통정보를 수집하려고 할 때 관측자가 카메라를 움직이면 설치된 검지영역이 손실되고 복원하려고 해도 기계적 오차로인해 어려움을 겪게 된다. 그래서 어안이나 거울을 이용하면 카메라를 움직이지 않아도 된다. 하지만 이러한 상황하에서 가장 큰 문제점은 영상의 왜곡이다. 본 논문에서는 이러한 왜곡을 극복하기 위해 비선형 확산 방정식을 이용한 분할과 이 영역에디포메이션을 적용하여 디블러링 한 후 차량정보 수집을 시도한 결과 이전 결과보다 5% 향상된 결과를 얻었다.

• 한국재료학회지
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• 제32권2호
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• pp.107-113
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• 2022

Fibrous supercapacitors (FSs), owing to their high power density, good safety characteristic, and high flexibility, have recently been in the spotlight as energy storage devices for wearable electronics. However, despite these advantages, FCs face many challenges related to their active material of carbon fiber (CF). CF has low surface area and poor wettability between electrode and electrolyte, which result in low capacitance and poor long-term stability at high current densities. To overcome these limits, fibrous supercapacitors made using surface-activated CF (FS-SACF) are here suggested; these materials have improved specific surface area and better wettability, obtained by introducing porous structure and oxygen-containing functional groups on the CF surface, respectively, through surface engineering. The FS-SACF shows an improved ion diffusion coefficient and better electrochemical performance, including high specific capacity of 223.6 mF cm^-2 at current density of 10 ㎂ cm^-2, high-rate performance of 171.2 mF cm^-2 at current density of 50.0 ㎂ cm^-2, and remarkable, ultrafast cycling stability (96.2 % after 1,000 cycles at current density of 250.0 ㎂ cm^-2). The excellent electrochemical performance is definitely due to the effects of surface functionalization on CF, leading to improved specific surface area and superior ion diffusion capability.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.456-462
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• 2001

Comprehensive numerical computations are made of a homogenous spin-up in a cylindrical cavity with a time-dependent rotation rate. Numerical solutions are acquired to the governing axisymmetric cylindrical Navier-Stokes equation. A rotation rate formula is ${\Omega}_f={\Omega}_i+{\Delta}{\Omega}(1-{\exp}(-t/t_c))$. If $t_c$ is large, it implies that a rotation change rate is small. The Ekman number, E, is set to $10^{-4}$ and the aspect ratio, R/H, fixed to I. For a linear spin-up(${\epsilon}<<$), the major contributor to spin-up in the interior is not viscous-diffusion term but inviscid term, especially Coriolis term, though $t_c$ is very large. The viscous-diffusion term only works near sidewall. But for spin-up from rest, when $t_c$ is very large, viscous-diffusion term affects interior area as well as sidewall, initially. So azimuthal velocity of interior for large $t_c$ appears faster than that of interior for relatively small $t_c$. However, the viscous-diffusion term of interior decreases as time increases. Instead, inviscid term appears in the interior.

• 한국연소학회지
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• 제7권3호
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• pp.9-15
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• 2002

Soot generation by combustion process has been investigated with objective of understanding of chemical reaction responsible for its formation in a coaxial laminar propane jet diffusion flame. For the direct photos, as the coflowing air flow rate is reduced, the area of soot luminous zone increases at first, then becomes smaller and smaller, and even disappears. The aspects of soot deposition can be acquired by using nine $15{\mu}m$ thin SiC fibers are positioned horizontally across the flame. Deposited soots on SiC fibers show the soot inception point and growth and soot oxidation zone in a typical propane diffusion. Soot is not generated anymore in a oxidizer deficient conditions of near-extinction and flame is fully occupied by transparent blue flame. It suggests that nonsooting pyroligneous blue reaction is being dominant in a oxidizer deficient ambience. In comparison with luminosities of SiC fibers and flame itself, indirect evidence is found that the process of soot nucleation and growth is endothermic reaction. It is remarkable that there exists two adjacent regions to have antithesis characteristics; one is exothermic reaction of blue flame and another endothermic reaction zone of soot formation.

• Ocean and Polar Research
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• 제26권1호
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• pp.33-42
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• 2004

Effect of freshwater discharge on the long-term salt balance in the Northern and Central Indian River Lagoon (IRL) is successfully simulated by a new analytical solution to a water balance-based one-dimensional salt conservation equation. Sensitivity tests show that the salinity levels drop abruptly even during the dry season (November to May) due to the high surface runoff discharge caused by tropical storms, depressions, and passage of cold fronts. Increasing surface runoff and direct precipitation has risen by ten times, lowering the salinity level down to 12psu in the Northern Central zone, and to 17 psu in the Northern zone. However, the salinity level in the Southern Central zone has decreased to 25 psu. High sensitivity of the Northern Central zone to freshwater discharge can be partially explained by a rapid urbanization in this zone. During the dry season, less sensitivity of the Southern Central zone to the increased surface runoff is attributed to the proximity of the zone to the Sebastian Inlet and a strong diffusion condition possibly resulting from the seawater intrusion to the surficial aquifer at the Vero Beach. During the wet season, however, the whole study area is highly sensitive to freshwater discharge due to the weak diffusion conditions. High sensitivity of the IRL to the given diffusion conditions guarantees that the fresh-water release occurs during strong wind conditions, achieving both flood control in the drainage basin and a proper salinity regime in the IRL.