• Education of Primary School Mathematics
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• v.25 no.1
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• pp.81-100
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• 2022

The purpose of this study is to develop a framework for analyzing the solution spaces of open-ended task and to explore their usefulness and applicability based on the analysis of solution spaces constructed by students. Based on literature reviews and previous studies, researchers developed a framework for analyzing solution spaces (OMR-framework) organized into subspaces of outcome spaces, method spaces, representation spaces which could be used in structurally analyzing students' solutions of open-ended tasks. In our research, we developed open-ended tasks which had various outcomes and methods that could be solved by using the concepts of factors and multiples and assigned the tasks to 181 elementary school fifth and sixth graders. As a result of analyzing the student's solution spaces by applying the OMR-framework, it was possible to systematically analyze the characteristics of students' understanding of the concept of factors and multiples and their approach to reversible and constructive thinking. In addition to formal mathematical representations, various informal representations constructed by students were also analyzed. It was revealed that each space(outcome, method, and representation) had a unique set of characteristics, but were closely interconnected to each other in the process. In conclusion, it can be said that method of analyzing solution spaces of open-ended tasks of this study are useful for systemizing and analyzing the solution spaces and are applicable to the analysis of the solutions of open-ended tasks.

• Journal of Preventive Medicine and Public Health
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• v.2 no.1
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• pp.23-59
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• 1969

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2001.09a
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• pp.15-18
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• 2001

Sixty natural springs and wells used as community facilities for drinking water are developed along mountain climbing way of suburban area and residential area in Daejeon City. In this study, the seasonal variation of their water quality and hydrochemical characteristics were investigated. Some natural springs are vulnerable to bacilli contamination because of their short residence time and shallow circulation in subsurface environment. The waters show hydrochemical types of Ca-HCO$_3$ and Na-HCO$_3$, and are characterized by low electrical conductance and weak acidic pH.

• Journal of the Korean Institute of Telematics and Electronics
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• v.11 no.2
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• pp.40-45
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• 1974

It is indicated that in SCR the anode current can be controlled by ajusting the gate voltage when the magnitude of anode current lies in the range of 10-2 to 10-3 Amperes. This fact is applied to make a simple sinusoidal oscillator circuit which has the negative resistance characteristics in its gate circuit by inserting a proper resistor into its cathode circuit.

• Journal of Korea Game Society
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• v.13 no.2
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• pp.49-58
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• 2013

In this study, a tree growth model is designed to represent a variety of trees consisting of a outdoor terrain of game efficiently and naturally. The proposed tree growth model is an integrated tree growth model, and is configured using the following approaches: (1) the tree modeling method based on growth volume and the convolution sums of divisor functions, which is used to model a variety kind of trees more intuitively and naturally; (2) a rendering method using a level of detail of branch based on instancing for real-time processing of numerous trees with complicated structures; and (3) a combination of the above methods to efficiently implement a game landscape. The natural and diverse growths of trees that emerged using the proposed tree growth model is evaluated through experimentation, along with the possibility of implementing the natural game landscape and the efficiency of real-time processing.

• Journal of Food Hygiene and Safety
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• v.13 no.3
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• pp.305-312
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• 1998

In order to investigate the species, serobiological characteristics and antibiotic sensitivity of Pseudomonas spp, we isolated Pseudomonas spp from 57 spring waters around Seoul area for spring, summer and autumn and identified Pseudomonas spp by biochemical characteristics and serological method. And also we tested the antibiotic sensitivity test by discdiffusion method. Of 57 spring waters tested, Pseudomonas spp were isolated from 33 spring waters(57.9%). Isolation rate of Pseudomonas spp in spring season was 28.1%, summer 21.1% and autumn 28.1%. Only 1 spring water was detected Pseudomonas spp in all seasons and 9 (15.8%) were detected for 2 seasons and 13 (22.8%) were for only 1 season. Isolation rate of Pseudomonas spp at Mt. Cheonggye was 50% and followed by Mt. Bookhan 35.7%, Mt. Daemo 33.3%, Mt. Dobong 29.6%, Mt. Surak 25.9%, Mt. Woomyun 22.2% and Mt. Bulam 7.4%. Of 44 Pseudomonas spp, 22 strains (50%) were identified by Ps. putida, Ps. aeruginosa, Ps. fluorescens and Ps. mendocina were identified 6 strains (13.6%), respectively. 4 strains (9.1%) were identified by Ps. aureofaciens. Of 6 Ps. aeruginosa, serotype A was 2 strains, B, E, G, and K was 1 strain, respectively. Of 44 Pseudomonas spp, resistance rate to amoxicillin was 90.9% and followed by chloramphenicol 84.1%, tetracycline 84.1%, carbenicillin 81.8%, nalidixic acid 68.2%, neomycin 38.6%, streptomycin 31.8%, gentamicin 4.6%, kanamycin 4.6% and colistin 2.3%. Ps. aeruginosa was more sensitive to carbenicillin than other Pseudomonas spp isolated from spring waters in Seoul area but more resistant to kanamycin, and Ps. aureofaciens was no resistant to streptomycin. Among multiple drug resistance, resistance to 5 drugs was 31.8%, 4 drugs 15.9%, 7 drugs 13.6%, 1 drug and 2 drugs 4.6%, and 8 drugs 2.3%, respectively. The multiple resistance patterns detected highestly were NA-CB-C-TE-AMC (18.2%), NA-CB-N-C-TE-AMC (13.6%), CBC-TE-AMC (11.4%) and NA-CB-N-C-TE-AMC-S (9.1%).

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.126-135
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• 1987

The physical properties, coliform groups, and nutrients were investigated to evaluate the sanitary Quality of the environmental water at Chinju area from May to October, 1986. The results were as follows : The pH ranged from 5.4 to 7.8 : water temperature ranged from 12.0 to $30.3^{\circ}C$ : electrical conductivity ranged from $0.51\times10^2\;to\;8.095\times10^2\mu\mho/cm$; chloride ion ranged from 3.6 to 126.8 mg/l, respectively. Especially, the concentration of the chloride ion at St.9 was 109mg/l which was higher than those of others. The $NO_3^--N$ ranged from 0.2336 to 14.1648 mg/l and the mean value was 5.4774 mg/l, the concentration of $NO_3^--N$ at St. 2 was higher as 40 times than that of St.4. The $PO_4^{3-}-P$ ranged from 0.0013 to 0.8315 mg/l, and the mean value was 0.0745 mg/l, the concentration of$PO_4^{3-}-P$ at St.8 was higher than that of others. The $SiO_2-Si$ ranged 1.7 to 15.28 mg/1 and the mean value was 5.81 mg/l. The value of St.8 and St.9 were higher than those of other stations but this value were lower $10\~13\;mg/l$ than the criterion for drinking water as 50 mg/l. The bacterial density of the spring waters ranged 9.1 to 4,600/100 ml (geometric mean : 205/100 ml) for total coliform 0 to 4s0/100 ml and 28.2/100 ml for fecal coliform. Composition of coliform was $38.2\%$ Escherichia coli, $25\%$ Entrobacter aerogenes, $13.2\%$ Citrobecter freundii and the others.

• Journal of the Korean Geographical Society
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• v.35 no.3
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• pp.473-488
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• 2000

본 연구는 관광경기 침제현상으로 지역 전체가 몸살을 앍고 있는 수안보온천의 현재의 단계를 관광지 라이프사이클 모델에 근거하여 진단하고 이에 따른 활성화 방안을 제시하는데 목적이 있다. 수안보온천은 관광지 라이프사이클에 따르면 1998년 이래로 관광시장의 축소, 편의시설의 소명, 주말 및 당일 체류관광객의 증가 등의 관광지 쇠퇴단계의 지표가 나타나고 있다. 쇠퇴단계에 이른 수안보온천의 가장 큰 문제점은 관광 편의시설물의 노후화와 자본이 부족하다. 이러한 문제점을 해결할 수 있는 방안에는 다음 세가지가 있다. 첫째는 기존 시설물을 일부만 변경하며 노년층의 영구 거주지로 분양하는 것이다. 둘째는 방치괸 야외무대장을 주말 상설놀이마당으로 활용하고, 섯째는 수안보온천 관광호텔 자리에 있는 냉천을 약수로 개발하여 관광자원화하는 것이다.

• Review of KIISC
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• v.14 no.3
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• pp.1-7
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• 2004

양자알고리듬들 중 쇼의 알고리듬은 공개키 암호체계의 근간을 이루는 소인수분해를 고전알고리듬보다 훨씬 빨리 처리할 수 있다. 고전컴퓨터로 N자리 수를 소인수분해 하는데 걸리는 시간은 exp$[(InN)^{1/3}(In In N)^{2/3})]$에 비례하지만 쇼의 양자풀이법을 사용하면 약$(InN)^3$ 보다 적은 시간이 걸린다. 이 알고리듬의 핵심은 양자계의 중첩이라는 성질을 이용해서 푸리에 변환을 모든 데이터에 대해 병렬적으로 동시에 처리함으로서 주기를 빠르게 찾는다는 것이다. 이러한 양자전산의 이점은 모든 연산이 중첩된 상태에 독립적으로 작용한다는 자연계의 선형성에서 비롯된다. 고전컴퓨터에서도 병렬처리를 하지만 양자적 병렬처리를 고전컴퓨터의 병렬처리로 대신할 수는 없다. N비트로 나타내지는$2^N$ 개의 숫자에 대해 동시에 병렬처리 하는데 양자컴퓨터는 한대면 되지만 고전컴퓨터는 $2^N$대가 필요하므로 비트수가 증가하면 필요한 고전컴퓨터의 수가 비현실적으로 증가하기 때문이다. 이 알고리듬의 수행으로 얻어지는 결과는 확정적인 것이 아니며 확률적으로 율은 당을 얻는다. 어떤 수가 약수가 되는지 아닌지는 금방 확인해 볼 수 있으므로 서너 번 이와 같은 시행착오 과정을 거쳐 옳은 답을 얻는다 해도 문제가 되지는 않는다.

• Journal of Preventive Medicine and Public Health
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• v.5 no.1
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• pp.37-42
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• 1972

Mountain Wells are very important water source for the most of the climbers in Seoul area. But the facilities around the wells are not modernized to prevent from contamination of microorganism and the other pollutants. We focussed our intention on the detection of some harmful chemical ingredients and contaminants. A total of 58 wells were examined according to the Standard Methods(APHA) and the following results were obtained: 1) Among the examined 58 wells, only 10 wells were adequate to the drinking water standard, 2) 7.9mg of liberated $CO_2$ was found in the Tchun-Ho-Dong Mineral Well, 3) Chemically harmful ingredients were not found, 4) The Mountain Wells were contaminated by Coliform groups as many as 18 times than rural wells.