• Title/Summary/Keyword: 여과지

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Pressure Loss in Canisters with Conditions of Activated Carbon Particles (활성탄 입자 조건에 따른 정화통의 압력손실 특성에 관한 연구)

  • Kim, Min-Wook;Kim, Young-Soo;Park, Yong-Hwan
    • Fire Science and Engineering
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    • v.31 no.4
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    • pp.7-11
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    • 2017
  • The use of special gas masks such as PAPR is strongly required for the safe and efficient work of fire-fighters in removing fire residue and rescue activity. Special gas masks commonly use canisters with carbon activated particles. This paper analyzed the pressure distribution, velocity distribution and pressure loss characteristics in canisters using CFD simulation, and showed pressure drops are affected by inlet air velocity, canister geometry and increase dramatically especially with the decrease of particle diameters and volume fractions.

한국산 해마의 서식지 보고 및 초기생활사

  • Roh, Seom;Choi, Yeong-Ung;Yoon, Yeong-Seok;Chung, Min-Min
    • Proceedings of the Korean Aquaculture Society Conference
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    • 2003.10a
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    • pp.56-57
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    • 2003
  • 실고기과(Syngnathidae)에 속하는 해마류는 5300만년전부터 지구상에 존재해온 어류로 전 세계적으로 72%에 해당하는 32종이 인도-태평양연안에서 서식하는 것으로 알려져 있다. 그리고 약제와 관상무역에서 넓은 시장을 형성하며 그 수요가 지속적으로 증가하고 있다. 그러나, 국내에서는 아직 해마의 서식지와 초기생활사에 대한 연구가 전무한 실정으로 이번 연구에서는 최근 발견된 한국산 해마의 서식지와 채집된 2종 해마의 치어 초기생활사를 보고한다. 2003년 8~9월에 전라남도 여수시와 고흥군 주변해역에서 해마, Hippocampus coronatus 18마리(전장 40.8~79.5mm), 산호해마 H, japonicus 80마리(전장 28.1~56.3mm)가 채집되었고, 순환여과식 사육수조에서 사육하면서 자연산란한 치어를 대상으로 초기생활사를 관찰하였다. 사육은 유리로 된 사각수조(50$\times$30$\times$28cm)에 여과조(26$\times$26$\times$28cm)를 연결한 순환여과시스템에서 실시하였으며, 사육수온은 26.0$\pm$0.5$^{\circ}C$, 염분 32$\textperthousand$ 전후, pH 7.74 전후 그리고 DO 6.8mg/$\ell$ 전후였다. 먹이는 부화 2일령까지는 로티퍼, Brachionus rotundiformis를 단독 급이하였고, 부화 후 3일령부터는 로티퍼와 알테미아, Artemia sp.를 혼합 급이하였다. 치어의 성장 측정은 만능투영기를 이용하여 각 20마리를 무작위 추출하여 측정하였고 각 측정 부위별로 0.001mm까지 측정하였다. 이번 조사에서 전라남도 여수시와 고흥군 주변해역에서 채집된 해마류는 해마(H. coronatus) 18개체, 산호해마(H. japonicus) 80개체의 2종이 채집되었고 순환여과시스템에 사육하던 중 5회 산란하였다. 해마(H. coronatus)는 부화 후 9~10일째에 Total length 11.67~15.98mm(평균 5.19mm, n=20), Trunk length 2.48~3.31mm(평균 2.63mm, n=20), Head length 1.31~2.27mm(평균 1.76mm, n=20) 그리고 Snout length 0.74~l.67mm(평균 1.09mm, n=20) 이었다. 한편, 부화 직후 산호해마(H. japonicus)의 치어는 난황을 거의 흡수한 상태였으며 부화 후 2~3일째 Total length 4.29~5.70mm(평균 5.09mm, n=30), Trunk length 2.06~2.73mm(평균 2.55mm, n=30), Head length 1.50~l.79mm(평균 1.06mm, n=30) 그리고 Snout length 0.81~l.14mm(평균 0.97mm, n=30)였다. 그리고 부화 후 5~6일째에는 Total length 4.33~6.33mm(평균 5.19mm, n=20), Trunk length로 2.48~3.31mm(평균 2.63mm, n=20), Head length 1.31~2.27mm(평균 1.76mm, n=20) 그리고 Snout length 0.74~l.67mm(평균 1.09mm, n=20) 이었다.

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Effect of Seed Weight and Storage Method on Germination and Seedling Growth of Camellia japonica (동백나무의 발아 및 유묘 생장에 미치는 종자 무게 및 저장방법의 영향)

  • Kang, Hee-Kyoung;Choi, Su-Ji;Song, Hong-Seon
    • Korean Journal of Plant Resources
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    • v.33 no.1
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    • pp.33-39
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    • 2020
  • This study was carried out to provide basic information for mass breeding and cultivating the saplings of Camellia japonica. The germination rates did not show definite tendency according to the changes of seed weight at room temperature and 4℃ dry storage conditions. The germination rate of 4℃ wet sand storage was increased with seed weight, but showed very low germination rate for 120 days of storage. The germination rate was above 80% in 60 days, 90 days and 120 days, respectively, at 4℃ wet filter paper storage conditions. The average days taken for those germinations were about 30 days at room temperature and 4℃ dry storage conditions, but wet storage (sand, filter paper) condition took the shortly nearly 13 days for those germinations. Leaf number, leaf dry weight, stem diameter and root dry weight were higher than total average by more than 1.21 g for seed weight. Stem length was higher than the average by more than 1.01 g, plant dry weight was higher than the average by more than 0.81 g, and stem dry weight was higher than the average by more than 0.61 g. In the case of seed weight becoming heavier, seedling growth was good but T/R ratio tended to decrease. In order to increase the mass production of seedlings using Camellia japonica seeds, we need to specify the weight and size of those seeds. The 4℃ wet filter paper storage condition was evaluated as the most efficient method for the seed storage used for seeding.

Evaluation of Photoneutron During Radiation Therapy when Using Flattening Filter and Tracking Jaw with High Energy X-ray (고 에너지 X선 방사선치료 시 Flattening Filter와 Tracking Jaw 사용에 따른 광중성자 발생 평가)

  • Park, Euntae;Jin, Seongjin;Park, Cheolwoo
    • Journal of the Korean Society of Radiology
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    • v.10 no.2
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    • pp.125-131
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    • 2016
  • Radiation therapy is usually using linear accelerator and used X-ray energy is also getting higher. Recently linear accelerators has been developed 3F mode and tracking jaw technology and that was applied for patient therapy. This study aims at measuring photoneutrons depending on the use of 3F and tracking jaw system when radiation is irradiated using a linear accelerator. The generation of photoneutrons of 3F system was 70% smaller than 2F system and that of tracking jaw system was 83% higher than static jaw system. Photoneutron value is relatively low. However, it must be minimized for Photoneutron exposure during radiation therapy.

Ranking by Inductive Inference in Collaborative Filtering Systems (협력적 여과 시스템에서 귀납 추리를 이용한 순위 결정)

  • Ko, Su-Jeong
    • Journal of KIISE:Software and Applications
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    • v.37 no.9
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    • pp.659-668
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    • 2010
  • Collaborative filtering systems grasp behaviors for a new user and need new information for the user in order to recommend interesting items to the user. For the purpose of acquiring the information the collaborative filtering systems learn behaviors for users based on the previous data and can obtain new information from the results. In this paper, we propose an inductive inference method to obtain new information for users and rank items by using the new information in the proposed method. The proposed method clusters users into groups by learning users through NMF among inductive machine learning methods and selects the group features from the groups by using chi-square. Then, the method classifies a new user into a group by using the bayesian probability model as one of inductive inference methods based on the rating values for the new user and the features of groups. Finally, the method decides the ranks of items by applying the Rocchio algorithm to items with the missing values.

A Recommender Agent using Association Item Trees (연관 아이템 트리를 이용한 추천 에이전트)

  • Ko, Su-Jeong
    • Journal of KIISE:Software and Applications
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    • v.36 no.4
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    • pp.298-305
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    • 2009
  • In contrast to content_based filtering systems, collaborative filtering systems not only don't contain information of items, they can not recommend items when users don't provide the information of their interests. In this paper, we propose the recommender agent using association item tree to solve the shortcomings of collaborative filtering systems. Firstly, the proposed method clusters users into groups using vector space model and K-means algorithm and selects group typical rating values. Secondly, the degree of associations between items is extracted from computing mutual information between items and an associative item tree is generated by group. Finally, the method recommends items to an active user by using a group typical rating value and an association item tree. The recommender agent recommends items by combining user information with item information. In addition, it can accurately recommend items to an active user, whose information is insufficient at first rate, by using an association item tree based on mutual information for the similarity between items. The proposed method is compared with previous methods on the data set of MovieLens recommender system.

Improvement of UCI Metadata and Resolution Service for Massive Contents Recommendation (대규모 콘텐츠 추천을 지원하기 위한 UCI 메타데이터와 변환서비스의 기능 개선)

  • Na, Moon-Sung;Lee, Jae-Dong
    • Journal of Korea Multimedia Society
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    • v.13 no.3
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    • pp.475-486
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    • 2010
  • Contents Recommender System predicts user's preferences towards contents, and then recommends highly-predicted contents to user. Digital Identifier plays its part in identifying abstract works or digital contents in digital network environment. Digital Identifier could be effectively used in content-based filtering and collaborative filtering that are mainly used in Contents Recommender Systems. Therefore, this paper proposes an improvement of UCI metadata and resolution service for effective use of UCI in massive contents recommender systems. UCI metadata is expanded by adding elements such as abstract, keyword, genre, age, rate and review. Resolution service allows the operation systems to collect user preference for content by including input part of preference in a result page. This paper also designs and implements an improved UCI operation system and shows that the proposed improvement of UCI metadata and resolution service could be used for massive contents recommendation.

Site Suitability and Developable Amount Assessment for Riverbank Filtration in the Han River (II) (한강에서의 강변여과수 개발을 위한 적지선정 및 개발가능량 산정(II))

  • Lee, Sang-Il;Yoo, Sang-Yeon;Lee, Sang-Sin
    • Journal of Korea Water Resources Association
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    • v.41 no.8
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    • pp.835-843
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    • 2008
  • In Korea, riverbank filtration has drawn attention since 1990's as an alternative having potential to stably meet the ever-increasing water demand. Some cities located in the Nak-dong River Basin are currently supplying water through riverbank filtration. This research is on the application of riverbank filtration for stable water quality in Seoul. For this purpose, we have evaluated developable amount of water with riverbank filtration for the Han River. This paper focuses on the Kwangnaru site, which was selected through a systematic analysis in the companion paper. We have conducted groundwater modeling for a proposed system of wells and an artificial lake. In the Kwangnaru district, the river length to constitute a well system was identified to be about 1,200m, due to the topography and the field condition such as ecosystem preservation zone. After many design changes, it was found that the maximum developable amount of $23.36\;million\;m^3$/year could be obtained, when 16 pumping wells were built in every 80 meters along with an artificial lake upstream.

A Method to Improve Energy Efficiency Using a Function that Evaluate the Probability of Attempts to Verify a Report at Intermediate Node in USN (USN에서 중간 노드에서의 보고서 검증 시도 확률 평가 함수를 이용한 에너지 효율 향상 기법)

  • Lee, Hyun-Woo;Moon, Soo-Young;Cho, Tae-Ho
    • Journal of the Korea Society for Simulation
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    • v.20 no.4
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    • pp.21-29
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    • 2011
  • Wireless sensor nodes operate in open environments. The deployed sensor nodes are very vulnerable to physical attacks from outside. Attackers compromise some sensor nodes. The compromised nodes by attackers can lead to false data injection into sensor networks. These attacks deplete the limited energy of sensor nodes. Ye et al. proposed the Statistical En-Route Filtering (SEF) as a countermeasure of the attacks. The sensor node in SEF examines the event reports based on certain uniform probability. Thus, the same energies are consumed in both legitimate reports and false reports. In this paper, we propose a method that each node controls the probability of attempts to verify a report to reduce energy consumption of sensor nodes. The probability is determined in consideration of the remaining energy of the node, the number of hops from the node to SINK node, the ratio of false reports. the proposed method can have security which is similar with SEF and consumes lower energy than SEF.

Sonication in the Analysis of Hexavalent Chromium in Welding Fume (초음파 전처리에 의한 용접 흄 중 6가 크롬의 분석)

  • Yoon, Chung-Sik;Paik, Nam-Won;Kim, Jeong-Han;Park, Dong-Uk;Choi, Sang-Jun;Kim, Shin-Bum;Chae, Hyun-Byung
    • Analytical Science and Technology
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    • v.12 no.5
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    • pp.447-459
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    • 1999
  • A study was conducted to compare three analytical methods for determination of hexavalent chromium in the welding fume. Precision and accuracy arc documented for colorimetric, ion chromatographic, and inductively coupled plasma-optical emission spectroscopic method. Evidence is presented that welding fume can affect the oxidation of trivalent chromium. A simple sonication extraction method, proposed in this study, instead of hot alkaline extraction has the advantage of minimizing the potential for chromium oxidation.

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