고분자압출성형용 Single-Screw에 관한 열유동 기초연구

정효희,김재열,고명석,최승현,심재기,한재호 한국공작기계학회 2008 한국공작기계학회 춘계학술대회논문집 Vol.2008 No.-

Extrusion Screw, point parts of extrusion molding extruder, is expanded widely use area with construction machinery, site conveyance device food processor, medicine as well as Polymer extrusion forming. Because this can expect large quantity demand about Screw of special quality of extrusion Screw item, is become processing industry that adopt all kinds of small quantity production type. Accordingly, analysis by extrusion screw is also consisting of several directions. Extrusion screw differentia is appeared much at material selection of screw itself and each screw design as parts that cause a lot of high temperature and high tension and attrition among processing of product and use purpose and that should do it so that working conditions back according to kind of used balance may optimize of each Screw are desirable. In this treatise, analyzed and analyze single-screw that is using developing in Human Resource Training Project for regional Innovation subject considering pressure, temperature etc.. of extrusion screw using CFdesign that is 3 dimensional analysis program.

유기농업에서의 작물의 양분관리

안난희, 신재훈, 옥정훈, 이상민, 김석철, 사동민 忠北大學校 農業科學硏究所 2016 農業科學硏究 Vol.32 No.2

Soil fertility is fundamental in determining the productivity of all farming systems and is most�ﾠ�ﾠ commonly defined in terms of the ability of the soil to supply nutrients to crops. Organic farming systems rely on the management of soil organic matter to enhance the chemical, biological and physical properties of the soil, in order to optimize crop production. Organic agriculture excludes the use of chemical nitrogen fertilizers, instead requiring a balance between supply and demand nutrients through the use of organic matter. Nutrient management is one of the main challenges facing organic farming. The short term challenge is supplying sufficient nutrients to crops at the correct point in their development to achieve economically viable yield, while in the long term, the difficulty is to balance nutrient inputs and runoffs to avoid nutrient rundown or environmental pollution. This paper reviews information from the literature to investigate strategies of managing nutrients by supplying organic matter in organic agriculture during the major phases of crop growth.

최적설계 기법을 적용한 1톤 운반차용 P.T.O축 및 트랜스미션 개발에 관한 기초연구

김재열,심재기,최승현,정효희,김훈조,오현중,박경섭 한국공작기계학회 2007 한국공작기계학회 추계학술대회논문집 Vol.2007 No.-

Now, power tillers and cultivators which are spread among fruit tree households have usage, low application, and high accident risk. Therefore, the development of multi-purpose work vehicles is needed as an alternative for these problems. Especially, easy usage and the ability to easily change gears when driving and the development of the P.T.O for various tasks such as pruning, water lifting, pest control, application and, mowing are needed. In this research, we will develop a transmission with design on P.T.Oaxle for agricultural work vehicles including multi-purpose vehicles. We aim to develop a 4-wheel drive transmission of synchronous contact type for practical use in fruit tree households which is required to be a large-sized agricultural vehicle. Therefore, we have per performed as follows that are composed of load capacity from 500kg to 1,000kg, safety securing for passengers, and drive securing under bad conditions of the topography slope and swampy land and the rest. For this purpose, we have developed a prototype vehicle through strength analysis of transmission design. we have selected optimal design conditions (Optimal RPM and torque according to some works) on the power transmission with multi-purpose vehicle for various jobs: spraying, manure spreading, mowing, brush wood chopping. If development of the P.T.O containing variable RPM and torque is successful, the following tasks can be possible. Air pruning, air maintenance, water lift, pest control, application, mowing, spraying, and brush wood chopping are possible with this developed P.T.O. Methods and contents for research are followed. Therefore, we have achieved performance-tests through the prototype of the multi-purpose work vehicle and have improved on troubles by the analysis of results of R&D. Also, we provided solutions to problems in mass production in the future.

고분자튜브용 Single-Screw 압출시스템의 동적특성 해석

김재열,정효희,최승현,최진호,홍철 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

Today, Screw model used in extrusion molding of to analyze various simulation notations as well as an experiments use, and is using because among them, third dimension technique among present technique accomplishes most troop. Because that third dimension uses technique does not attain explanation that is correct in model who curt analysis notation on two-dimension has complex shape structure. Is studying measurement of shape of extruder of complicated structure or frictional force of polymer balance and density, applied mechanism accordingly using third dimension technique. Single screw system, analysis target of this treatise, is extruder that extrusion molding that use most polymer resin consists. Most single screw extruder is excellent transfer in melting state of polymer balance, but there are some shortcomings. Melting of polymer balance and color dithering of balance are difficult and high heat of increase of screw speed of revolution to increase done balance quantity produces anaphora along with unmeasured shear force increase. Single screw that have this a lot of controversial points in addition to achieving dynamic analysis of single screw extruder of polymer tube that get into nature of a treatise that use CFdesign that is heat/flow analysis program production stability in single screw extruder system for polymer tube analysis achieve wish to.

형성평가에 대한 과학교사들의 인식 및 실태

南貞姬,成乙善,飮在鎬,金慶姬,崔秉舜 한국교원대학교 과학교육연구소 1999 청람과학교육연구논총 Vol.9 No.1

전국의 초, 중, 고등학교 과학교사 197명을 대상으로 과학교육에서 형성평가에 대한 인식 및 이에 대한 실태를 질문지를 이용하여 조사하였다. 교사들은 학교교육에서 평가의 가장 중요한 목적이 학습목표의 성취를 확인하기 위한 것이라고 생각하고 있었으며, 가장 적절한 평가방법은 형성평가라고 생각하고 있었다. 따라서 형성평가는 수업 후반부에 학습내용의 성취정도를 확인하는 평가라고 인식하고 있었다. 대부분의 교사들이 형성평가가 매우 필요하다고 인식하고 있었고, 그 이유로 학습목표 달성 정도의 확인을 들었다. 그러나 과학 수업 중 수시로 이루어지는 형성평가는 적었다. 형성평가의 실시를 어렵게 만드는 원인으로 학생 수 과다, 시간 부족, 준비의 어려움을 들었으며, 형성평가로부터 얻은 정보는 학생들의 성취수준을 판단하는데 이용한다고 응답하였다. The science teachers' perceptions and the status of formative assessment in science teaching were identified through a questionnaire. The majority of teachers thought that the most important goal of assessment in education was to identify to what extent pupils achieved learning objectives. They suggested that formative assessment was the most appropriate method regardless of the purposes of assessment. They thought that formative assessment was an assessment carried out at the end of lesson to identify to what extent pupils achieved learning objectives. The teachers stressed the need for formative assessment to identify what pupils achieved. But they carried out formative assessment about once a week and there were very few teachers carrying out formative assessment during the lesson. They responded that it was difficult to carry out formative assessment because of large class size, lack of time and difficulty in preparation. And they used the information from formative assessment to judge the level of attainment.

열수 및 마이크로웨이브처리 맹종죽재의 물리적·기계적 특성

신훈재,안상열,변희섭,박상범,공영토 한국목재공학회 2004 목재공학 Vol.32 No.2

열수 및 마이크로웨이브조사 처리가 별채시기 및 부위별에 따른 맹종죽재의 물리적 기계적 특성을 평가하고, 효율적인 연화조건을 탐색하기 위하여 경남 진주시 가좌동에 위치한 남부임업시험장내에서 생육이 양호한 1, 2, 3년생의 죽재를 8월과 1월에 벌채하여 실험한 결과는 다음과 같았다. 1. 윗부위, 중간부위, 아랫부위의 부위별에 따른 휨탄성계수의 차이는 윗부위가 가장 높은 값을 나타내었고 중간부위, 아랫부위 순으로 낮은 값을 나타내었으며 대부분이 70,000~110,000 kgf/㎠의 범위에 있었다. 2. 동적 탄성계수의 범위는 80,000~130,000 kgf/㎠의 범위로 정적 탄성계수보다 10~25% 정도 높게 나타났으며, 8월과 1월의 상관관계 R값이 각각 0.87과 0.68로 나타나 일반적인 목재와 같이 맹종죽재의 탄성계수 측정에도 비파괴 방법인 양단자유진동에 의해서도 예측 가능하였다. 3. 95℃의 열수로 처리했을 때 연화율은 10~30%를 나타내었다. 4. 생재 및 포수 두 조건 모두 마이크로웨이브조사 처리 시간이 길어질수록 탄성계수가 낮아졌으며, 20초 및 30초간 처리했을 때 생재 휨탄성계수의 약 50% 이하로 떨어져 생재를 20초간 마이크로웨이브조사 처리했을 때가 본 연구에서 죽재를 연화시키는데 가장 효과적인 방법이었다.

정보화사회와 미래의 과학 교육에 대한 고찰

박재호,김학수,이두희 부산대학교 사범대학 과학교육연구소 1996 科學敎育硏究報 Vol.23 No.-

We discuss the concept of imformation society and the middle school science education for the future information society. The discussions can be summarized as the followings ; 1. The information society can be realized by the renovation of informational techniques such as computer and electric communication. And the society will be heavily dependent on the various services, informations, and knowledges. 2. The educational curricula, educational method, and educational contents in the information society will be drastically different from today's and developed into the information-oriented ones.

6-치환된 1,3,5-trianzine-2,4-dithiol 유도체의 반응성 연구

김재종,이용희,성대동 동아대학교 기초과학연구소 2001 基礎科學硏究論文集 Vol.18 No.1

Several 6-substituted-1,3,5- triazine-2,4-dithiol derivatives were prepared and their infrared were recorded on KBr disk. All these compounds show distinctly separate absortion bands for C-S and C-N streching. Each of these bands is split into a doublet. This is explained in terms of the existence of rotational isomers.

스테인리스강관 단주의 내력 및 거동에 관한 실험적 연구

유재희,장호주,양영성 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1(구조계)

This study attempts to uniform compressed test with stainless steel stub-columns, which gas corrosion resistance, fire resistance efficiency and elongation, for the use of It as structural members. Width(Diameter)-thickness ratio and steel tubular-section shape(pipe and tube) are selected experimental parameters. 0.1%off-set yielding strength was presented 4.067tf/cm², and strain at tensile strength was presented 0.734x1000000 in tensile test. 0.1%off-set yielding strength each specimen was higher than the design strength of structural members(2.4tf/cm²), and they were reached ultimate compressed strength. The results of this study can be applied to 2.4tf/cm² in KS yielding strength of stainless steel, and it can be relaxed the width(diameter)-thickness ratio limit value. And stainless steel was showed superior plastic deformation.

펠렛형 제올라이트를 이용한 이산화황의 흡착특성

이재희,김정국,양희철,김준형,이제근 한국화학공학회 2003 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.41 No.1

KA, NaA, CaA 및 NaX 제올라이트가 충전된 실험실 규모의 흡착층을 이용하여 SO_2 유입농도, 충전층 높이 및 공간속도를 변화시키면서 SO_2 흡착실험을 수행하였다. 평형흡착량과 파과시간 모두 제올라이트 세공크기에 따라 KA, NaA, CaA, NaX 순으로 증가하였다. NaX상에서 SO_2를 흡착시킬 경우 SO_2 유입농도 504ppm 이하에서 파과시간은 증가하나 역시 물질전달범위도 증가하여 물질전달 속도는 감소하였다. Wheeler 식으로부터 제올라이트상의 파과시간에 대한 평형흡착량, 공간속도 및 1/C_0의 관계를 확인한 결과, 504ppm 이상보다 504ppm 이하의 저농도에서 파과시간이 상대적으로 증가하였다. The experimental of SO_2 adsorption, with varying SO_2 concentration, packed-bed depth, and space velocity, was carried out using a lab-scale fixed bed with zeolites, such as KA, NaA, CaA and NaX. Both of an equilibrium adsorption capacity and a breakthrough time increased with zeolite pore size, in order of KA, NaA, CaA and NaX. Breakthrough time of NaX increased under SO_2 concentration of 504 ppm, but mass transfer rate decreased due to expansion of mass transfer zone. Breakthrough time is relatively increased in the low gas concentration(<504 ppm) more than high concentration(>504 ppm), which is proved by the effects of equilibrium adsorption capacity, space velocity and l/C_0 for the zeolite from the relationship of Wheeler equation.