• Korean Journal of Ichthyology
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• v.19 no.1
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• pp.24-34
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• 2007

After releasing more than 1,000,000 fertilized eggs of Plecoglossus altivelis into Lake Okjeong, Jeollabuk-do, on October, 2001 by KOWACO, they seem to be land-locked. Study on the distribution and ecology of a land-locked ayu, P. altivelis, was performed from Lake Okjeong to upper streams as Jowon, Churyeong, Oknyedong where consisted of rocky bottom with fast current freshwater system during April to October. The hatched larva and juveniles descended from streams to Lake Okjeong and inhabit Lake Okjeong from November to next March. The sex ratio of female to male was 1 : 2.70, and the size in standard length of females and males was similar, in $90{\sim}220(142{\pm}29.3)mm$. During the middle September to the middle October, they laid eggs on the pebbly bottom of the rapids which are $20{\sim}22^{\circ}C$ in water temperature and 30~70 cm in depth. The number of full-grown eggs was greatly various from 14,283~91,500.

• Applied Microscopy
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• v.29 no.2
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• pp.177-187
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• 1999

Ultrastructure of gametes in the three-spine stickleback, Gasterosteus aculeatus aculeatus was observed, utilizing light, scanning and transmission electron microscopes. The egg of three-spine stickleback is spherical and demersal type. The eggs are highly adhesived to each other but not to substrates. There are many oil droplets in vitelline membrane. The outer surface of egg envelope is arranged by mushroom-like structures and pore canals. The egg have a micropyle, sperm entry site, in the area of the animal pole. The egg envelope consists of three layers, an outer layer with high electron density, a middle layer consisting two layers and an inner layer consisting of 16 to 20 layers. In the fertilized egg envelope, the molecular weights of these components ranged from 14 kDa to 205 kDa. The molecular weights of nam protein bands are 19.4 kDa, 36.7 KDa, 39.4 kDa, 42.9 kDa, 46.1 kDa and 53.0 kDa. The head of spermatozoa is spherical shape and the acrosome is absent. The mitochondria in midpiece are arranged from one to three layers and separated from the axoneme by the cytoplasmic canal. The tail has two lateral fins and the axoneme is of the 9+2 structure.

• Korean Journal of Ichthyology
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• v.31 no.2
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• pp.67-76
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• 2019

This study was conducted from 2017 to 2018 to determine habitat aspects of Acheilognathus signifier, an endangered species reintroduced (2010~2012) to Heukcheon Stream, a tributary of the Hangang River, Korea. A total of 329 individuals were collected in 2017 (two surveys) and 723 individuals were collected in 2018 (four surveys) at about 5 km habitat area, including the discharge station. A. signifier's habitat was about 0.4 to 1.2 meters deep in slow water flow upstream of the discharge area. It was a place with many boulders and cobbles. The spawning period was estimated from April to June in terms of spawning behavior and collected juvenile size. Sex ratio of females (438) and males (412) was 1 : 0.94. Estimated age of A. signifier based on their total length distribution during the spawning period (April) indicated that 1-, 2-, 3-year old groups and more than 4-year-old group were 32~43 mm, 50~61 mm, 62~75 mm, and 76~89 mm, respectively. Age-specific composition costs differed depending on the timing of the collection. They were relatively high in the order of first-year (juvenile)>third-year> and fourth-year or higher, showing a stable age structure. Thus, A. signifier reintroduced to Heukcheon Stream has successfully settled down and formed a stable population, showing a tendency to proliferate.

• Korean Journal of Ichthyology
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• v.35 no.3
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• pp.160-170
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• 2023

Life history of the endangered endemic species, Rhynchocypris semotilus, was investigated to obtain baseline data for its ecological characteristics in Songhyeoncheon, Hyeonnae-myeon, Goseong-gun, Gangwon-do, Korea from April to October, 2022. A total of 10 families and 18 species of fishes were collected from 4 survey stations, and R. semotilus was a subdominant species in the survey period (seven times). The main habitat of R. semotilus was the middle-upper stream of rock and boulder bottoms with aquatic plants and slow rapids and pools. The age groups for R. semotilus estimated by the frequency distribution of total length in spawning season (May) indicated the 4~12 mm is 0-year old, 32~49 mm is 1-year old, the 50~65 mm group is 2-years old, the 66~91 mm is 3-years old, and the 92~116 mm is more than 4-years old, and showed rapid growth from May to September. Total length range of female and male were the relatively similar, and sex ratio (♂/♀) was 0.78. The spawning period is from May to July (water temperature is 17 to 21℃), and gonad was developed more than three years old (more than TL 66 mm). In May, the gonadosomatic index (GSI) was 10.6±2.99% for females and 8.2±2.34% for males, fecundity was 6,830±1,943, and mature eggs size was 1.34±0.16 mm. Finally, life history characteristics of R. semotilus was discussed between the genus Rhynchocypris and Phoxinus species.

• Journal of Environmental Impact Assessment
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• v.26 no.6
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• pp.538-552
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• 2017

In this study, total mercury (THg) of Black-tailed Gull (Larus crassirostris) eggs laid on Baengnyeongdo, West Sea of Korea was analyzed in order to compare the THg concentrations of eggs depending on egg-laying order. The first-laid eggs ($mean{\pm}standard$ error, $234.4{\pm}11.2ng/g\;wet$, n=18, t=8.4, p<0.01) significantly had higher THg concentrations than the second-laid eggs ($182.8{\pm}9.1ng/g\;wet$, n=18). Also, the first-laid eggs had higher values in biometrics (length $63.10{\pm}0.49mm$, t=2.4, p<0.05; width $44.51{\pm}0.19mm$, t=4.3, p<0.01; weight $65.53{\pm}0.87g$, t=4.2, p<0.01) than the second-laid eggs (length $62.37{\pm}0.40mm$, width $43.55{\pm}0.17mm$, and weight $62.48{\pm}0.72g$). These differences might be attributed to the amount of food eaten by females relating to males' courtship feeding pattern (males increase courtship feeding rate before the first eggs are laid, and decrease the rate following the laying of the first eggs). Moreover, the lower food intake of females could diminish the quantities of egg albumen that contains a protein binds to most of methylmercury during the period of egg production. Therefore, it is necessary to consistently apply one of egg selection methods (targeted selection (the first-laid egg or the second-laid egg), random selection, and etc.) in one nest for ensuring comparability of mercury concentrations among monitoring sites and monitoring years.

• Fire Science and Engineering
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• v.18 no.4
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• pp.78-85
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• 2004

This research analyzes Clean Room accidents, and presents research Clean Room, major fire prevention standards of Clean Room (FM, IRI, and NFPA Code), various results from Fire Simulation of analysis. The results are : the smoke diffusion is very quick coupled with the Heating, Ventilating, and Air Conditioning (HVAC) systems under fire ; the possibility of getting the result and the possibility the role of the Sprinkler systems to reduce the diffusion of the smoke. We learn about the importance to stop operating Heating, Ventilating, and Air Conditioning (HVAC) systems and to operate the Sprinkler system for securing safety with fire detection. Therefore, This research will be contributing to secure safety of Clean Room.

• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.251-256
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• 2001

The influences of decorrelation on phase sensitivity are studied with a computer simulation based on the Bayesian theorem, when correlated photons produced by parametric down-conversion are incident on a Mach-Zehnder interferometer. Although the down-converted photons show a perfect correlation in the production process, this degree of correlation may be decreased by reflection, absorption, and scattering during propagation. It is found that this decorrelation results in phase sensitivity degradation, and that the sensitivity is related to the detector quantum efficiency. The results show that when the phase difference between the two paths is smaller the phase sensitivity is better. etter.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.172-172
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• 2017

본 연구는 차량의 AW(AutoWiping) 기능을 위해 장착된 강우센서를 이용하여 강우정보를 생산하는 기술을 개발하고자 하였다. AW(AutoWiping) 기능이란 차량 앞창(Windshield)에 빗방울이 맺히게 되면 광신호의 산란으로 인해 수광부에 들어오는 감소되는 광신호의 정도에 따라 차량 와이퍼의 속도를 결정해 주는 기능이다. 빗방울이 많이 맺힐수록 광신호는 감소되며 와이퍼는 더 빠른 속도로 작동을 하게 된다. 여기서 강우센서가 강우량이 많으면 감소된 광신호 데이터를 표출하는 현상을 이용하여 강우정보를 생산한다. 강우센서는 총 8개의 채널로 이루어져있고, 초당 250개의 광신호 데이터를 수집하며, 10분이면 약 120만 개의 데이터가 생산되게 된다. 이 대량의 데이터에서 정확한 강우량을 산출하기 위해 강우센서의 초기값과 와이퍼 이동시 발생하는 순간 이상치를 제거해야 한다. 하지만 일일이 수백만 개 이상의 데이터에서 모든 이상치를 제거하는 작업은 불가능하다. 따라서 이상치를 포함한 회귀 분석 방법을 연구하였고, 인공강우 발생기를 이용하여 광신호를 강우량으로 환산하는 2가지 회귀식이 유도되었다. 이들은 각각 이상치를 모두 포함시켜 독립변수(광신호)에 따라 종속변수(강우량)의 값이 변화하는 관계를 나타내는 선형회귀분석(model 1), 임계치를 정하여 일정 이상치가 제거된 신호만 통과시키는 대역통과 필터링 분석(model 2)으로 유도된 회귀식을 실강우에 회귀식을 적용하여 정확도를 분석하였다.

• Journal of Astronomy and Space Sciences
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• v.18 no.3
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• pp.239-248
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• 2001

Far-ultraviolet IMaging Spectrograph (FIMS) is the main payload of the first Korean scientific satellite, KAISTSAT-4, which will be launched in 2002. Among the optical parts, parabolic cylinder mirror does not have any heritage from previous astronomical missions, so the manufacturing and testing process itself is a challenging issue. We describe the method of manufacturing and measuring of the off-axis parabolic cylinder mirror and our initial experiments to establish the entire manufacturing process. Using the method, the profile error can meet the specification of $lambda$ per cm which is closely related with the astronomical performances. In case of the surface roughness, temperature controlled pitch polishing reduces $R_{q}$ under 1 nm implying that scattering in the entire spectral range of FIMS is less than 2% of the incident UV light.

• Fire Science and Engineering
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• v.30 no.4
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• pp.27-38
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• 2016

The paper reports the development of a distributed temperature sensing (DTS) system, which is a fire detection system using optical sensor linear detectors that depends on foreign and domestic technologies. This study accordingly analyzed the electrical signal patterns of Raman scattering light mainly used for temperature sensing among back-scattered light generated in optical fiber by using an oscilloscope. Through the measurement results, it could be verified that the Stokes signal patterns had little change by the temperature increase, but the temperature-sensitive anti-Stokes patterns had relative increase of the changes. This study developed a K-DTS system, which is an optical sensor linear fire detection system composed of an optical repeater and a receiver that can detect fires using Raman scattering light. It could be verified that the developed K-DTS system satisfied the type approval standards through the sensitivity tests using the rate of rise type and fixed temperature type sensitivity testers. In addition, performance experiments have been performed for performance evaluation of the K-DTS system developed in comparison with S-DTS system which has been imported from abroad and widely used in Korea. It can be confirmed from the results of the performance experiments using model tunnels that comparable performances can be obtained in fire detection locations and the measurements of fire temperatures.