• Korean Journal of Optics and Photonics
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• v.16 no.1
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• pp.7-12
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• 2005

We have observed the nonlinear magneto-optic effect(NMOE) based on atomic coherence in $^{87}$ Rb D$_1$-line using the Rb vapor cell containing 50 Torr of Ne. The width of the NMOE signal was measured to be 2$\pi$${\times}$464 Hz, when the peak-to-peak B-field variation was 1 mGauss. The result of this work may be applied to a high-sensitivity magnetometer.

• Journal of Wetlands Research
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• v.15 no.3
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• pp.317-328
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• 2013

The aim of this study is to compare the effects of the maintenance water supply methods on the ecological restoration of 5 urban streams such as Mugeo cheon, Yaksa cheon, Yeocheon cheon, Myeongjeong cheon and Cheokgwa cheon in Ulsan metropolitan city. Water quality of the streams have been innovatively improved and the ecosystems have gradually been restored by supplying maintenance water constantly. However, we found that if the maintenance water was in a state of higher salinity or low quality, even enough supply was not helpful and even harmful for ecological restoration. We confirmed that the most important things to create or maintain from the urban stream to the ecological stream are that facilities like a walkway construction should be installed at least, supplying appropriate maintenance water, and a connection with the main stream.

• Journal of the Korean Society for Library and Information Science
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• v.31 no.2
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• pp.59-77
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• 1997

Multicultural literature serves as a device for mutual understanding of different cultural. racial, and ethnic groups. This sort of literature is like a window through which a reader can see what other value systems are. It also helps minority children discover their own cultural past and develop a sense of belonging. The purpose of this study is to investigate the general characteristics of East Asian American characters in English language children's fiction and to highlight the differences among three groups : Chinese Americans, Japanese Americans, and Korean Americans.

• Korean Journal of Optics and Photonics
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• v.31 no.6
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• pp.321-327
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• 2020

We investigated the light reflection from thin films coated on substrates. Using a prism with a high refractive index as the incident medium, the phenomena of the total internal reflection (TIR) of the prism/film/substrate system and the light coupling into the optical waveguide formed by the air/film/substrate system were comprehensively studied and compared. If the refractive index of the thin film is greater than that of the substrate, within the TIR region of the substrate, sharp reflection minima occur at specific angles where the waveguide modes are excited, that can be used to accurately measure the refractive index and thickness of a thin film. On the other hand, if the refractive index of the thin film is smaller than that of the substrate, such waveguide modes do not exist. In this case, although not so distinct as a bulk medium, the TIR effect of the thin film is still observable, accompanied by an interference pattern. In this study we analyzed the overall reflection phenomena occurring from prism/film/substrate structures, to investigate the possibility of measuring the refractive index of a thin film in both cases.

• Korean journal of applied entomology
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• v.56 no.2
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• pp.179-186
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• 2017

This study was conducted to monitor the insecticidal susceptibility of western flower thrip, Frankliniella occidentalis, which damage horticultural crops in the Gyeonggi area. Bioassays were conducted under laboratory and greenhouse conditions by using the recommended concentrations of commercial insecticides being used for the control of thrips. Neonicotinoid insecticides, especially acetamiprid (8%) soluble powder (SP), clothianidin (8%) SC, imidacloprid (10%) wettable powder (WP) and thiacloprid (10%) water dispersible granule (WG) were not toxic to F. occidentalis collected from horticultural crops. However, F. occidentalis collected from vegetable greenhouses was extremely susceptible to acetamiprid + spinetoram (6 + 4%) suspension concentration (SC), clothianidin + spinetoram (6 + 4%) SC and methoxyfenozide + spinetoram (6 + 4%) SC, which resulted in over 90% control of thrips. In the greenhouse test, spinetoram (5%) WG, which caused 100% F. occidentalis mortality in the laboratory test, showed 87.4, 88.0, and 98.3% control at 3, 6, and 9 days after treatment, respectively, while imidacloprid (10%) WP showed below 44% control. From the results of this study, spinosin insecticides, such as more than over 4 and 10% of spinetoram and spinosad, and pyrrole insecticide, such as 5% chlorfenapyr, are recommended for the effective control of F. occidentalis.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.50-50
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• 2018

본 연구는 국내 생육이 확인된 미기록 외래식물을 보고하고 그 특성을 기술하고자 한다. 가는잎가시상추(Lactuca saligna)는 국화과 다년생 초본이며 높이 10~65cm에 까지 자란다. 줄기에 난 잎은 피침형, 좁은피침형이며, 기부는 이저(耳底), 줄기를 반쯤 감싼다. 유라시아원산으로 지중해, 유럽온대까지 넓은 생육범위를 보인다. 한국에서는 부산, 울산 해안가 주변 공터에서 생육이 확인되었다. 부산, 울산 해안가 저지대를 중심으로 신속한 분포확산이 예상된다. 근연종인 가시상추의 국내 분포확산, 위해성 등을 고려할 때 가는잎가시상추에 대한 주의가 요구된다. 좀전동싸리(Melilotus indicus)는 해안 초지에 생육하는 일년초이며 높이 60cm까지 성장한다. 잎은 우상 3소엽, 소엽은 도란형~좁은도란형, 길이는 1~2.5cm이며 거치가 있다. 좀전동싸리는 국내생육하는 전동싸리와 매우 유사한 형태적 특성을 보인다. 좀전동싸리는 꽃의 길이 2~3mm 개화기는 4~5월이며, 전동싸리는 꽃의 길이 4~7mm 개화기는 7~11월로 차이를 보인다. 지중해, 유럽 남서부 원산으로 전세계적으로 온대 전역에 유입된 것으로 알려져 있다. 국내에서는 제주시 한림읍 옹포리 일대 해안가 저지대 공터 및 초지에서 생육이 확인되었다. 넓은 면적에서 분포하며 제주도에 정착된 것으로 판단된다. 나도뿔이삭풀은(Hainardia cylindrica) 해안 초지에 생육하는 일년초이며 높이 5~35cm까지 성장한다. 수상화서는 25cm에 이르며, 쇠뿔모양으로 단단하다. 소수는 화서 중축에 파인곳을 메우고 있으며, 길이 5~8mm 1개의 소화를 포함한다. 초형은 혁질이며 예두이다. 남아메리카원산으로 북아메리카, 호주 일본 등에 귀화되어 있다. 한국에서는 전라남도 완도군 신지면 신리 해안가 일대 공터 및 초지에 생육이 확인되었다. 나도뿔이삭풀속 Hainardia 은 국내 처음 보고되는 속이며, 뿔이삭풀과 유사한 형태적 특성으로 인해 국명을 신칭하였다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.8
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• pp.25-33
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• 2017

This paper reports the optical design of the MR-16 lamp series with a LED second lens and an aspherical plano-convex lens suitable for a simple and rapid injection molding fabrication method. The fabrication and performance evaluation of the MR-16 lamp series, which was designed with a narrow angular distribution of luminous intensity, were conducted to replace halogen lamps with LED lamps. Four types of LED lamps were fabricated, which have angular distributions of luminous intensity of $22.4^{\circ}$, $31.1^{\circ}$, $37.3^{\circ}$, and $59.9^{\circ}$ and luminous efficiencies of 76.5 lm/W, 75.2 lm/W, 72.0 lm/W, and 77.8 lm/W, respectively, while their spreading angles with an illuminance uniformity of 81% were $3^{\circ}$, $15^{\circ}$, $22^{\circ}$, and $49^{\circ}$, respectively. After eliminating a yellow tail of the LED lamps using a diffusion sheet, the angular distributions of the luminous intensity were measured to be $20.8^{\circ}$, $31.5^{\circ}$, $37.8^{\circ}$, and $68.7^{\circ}$.

• The Journal of the Acoustical Society of Korea
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• v.21 no.8
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• pp.708-718
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• 2002

In this paper, the problems in identifying the noise sources by using the sound intensity technique are dealt with for the general radiated near-field from vibro-acoustic sources. For this purpose, a three-dimensional model structure resembling the engine room of a car or heavy equipment is considered. Similar to the practical situations, the model contains many mutually coherent and incoherent noise sources distributed on the complicated surfaces. The sources are located on the narrow, connected, reflecting planes constructed with rigid boxes, of which a small clearance exists between the whole box structure and the reflecting bottom. The acoustic boundary element method is employed to calculate the acoustic intensity at the near-field surfaces and interior spaces. The effects of relative source phases, frequencies, and locations are investigated, from which the results are illustrated by the contour map, vector plot, and energy streamlines. It is clearly observed that the application of sound intensity technique to the reactive or reverberant field, e.g., scanning over the upper engine room as is usually practiced, can yield the detection of fake sources. For the precise result for such a field, the field reactivity should be checked a priori and the proper effort should be directed to reduce or improve the reactivity of sound field.

• Tribology and Lubricants
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• v.2 no.2
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• pp.12-19
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• 1986

Using emulsion lubricant whose cooling effect and incombustibility are good and which is economical, I investigated lubricative mechanism and the behavior of scattered particles in the elastic fluid lubrication region with the line contact between rollers and plates and the light interference system. The results of the study are as follows: (1) The flow in the squeeze oil film is considered as comparatively wide clearance and narrow one, and in the former case the effect of the distribution of particles and the velocity on the flow. In the latter case, emulsion particles stay in the clearance an the oil film changes with the decrease of the oil film thickness. (2) In the wide clearance the velocity difference of the flow O/W or W/O emulsion is inverse proportional to the particle size. In the narrow clearance the distribution of the remained drops is different from one another and the scattered particles change more easily in O/W type than in W/O type. (3) At the beginning of the EHL the stagnation region with slow flowing velocity exists and the behavior at the region is different depending on the particle size. (4) By observing the dischromatic light interference line, emulsion oil passing through EHL region and the crack behavior at the beginning of EHL were found.

• Journal of Korea Water Resources Association
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• v.37 no.5
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• pp.387-395
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• 2004

A computer model was proposed to simulate channel changes and bed material sorting of the meandering channels with different grain size in time and space simultaneously. The bed at the outside of the meandering channel with mixed sediments was scoured deeply and composed of coarser materials, and at the inside was aggradated and composed of finer materials. The sorting process started at the upstream inflection point and was finished at the downstream inflection point. At the natural with complicated boundaries and non-uniform grain sizes, the bed near the outside at the bend and narrow width was scoured deeper with coarse materials than in the channel with uniform grain sizes. The point bars showed lip at the inside near the bend and the bed materials were finer The bed at the outside near the bend and in the narrow width was scoured deeply with the coarser materials.