• Journal of Microbiology and Biotechnology
• /
• 제10권2호
• /
• pp.169-175
• /
• 2000

The filamentous soil bacterium Streptomyces coelicolor is known to produce four distinct antibiotics. The simultaneous global regulation for the biosynthesis of those four antibiotics was previously confirmed by absA and absB mutations that blocked all four antibiotics' biosynthesis without influencing their morphological differentiation. To study the complex regulatory cascade that controls the secondary metabolism in Streptomyces, a new abs-like mutation was characterized. namely absR, which is slightly leaky on a complete R2YE medium, yet tight on a minimal medium. A genetic analysis of the absR locus indicated that it is located at 10 o'clock on the genetic map, near the site of absA. A cloned copy of the absA gene that encoded bacterial two-component regulatory kinases did not restore antibiotic biosyntheis to the absR mutant. Accordingly, it is proposed that absR is another abs-type mutation which is less tight than the previously identified absA or absB mutations income medium conditions, and can be used to characterize another global regulatory gene for secondary metabolete formation in S. coelicolor.

• 한국정보통신학회논문지
• /
• 제13권2호
• /
• pp.437-444
• /
• 2009

유엔을 비롯한 국제단체와 각국의 정부에서는 공개 소프트웨어 보급을 위해 많은 노력을 기울이고 있다. 우리나라에서도 공개 소프트웨어를 활성화하기 위한 노력의 일환으로 공개소프트웨어 시범 사업을 시행하고 정보화 사업 평가 항목에 공개 소프트웨어 사용하면 가점을 부여하고 있다. 그러나 잠재적인 공개 소프트웨어 사용자들인 중등학교 학생을 대상으로 공개 소프트웨어에 대한 홍보와 교육이 부족한 상태이다. 본 연구에서는 현재 중등학교에서 학생들의 공개 소프트웨어에 대한 인지도를 파악하고 분석한다. 그리고 공개소프트웨어를 중등학교의 개정된 7차 교육과정 의 정보 교과에서 활용할 수 있는 방안을 제시한다.

• 대한전기학회논문지:전력기술부문A
• /
• 제51권10호
• /
• pp.495-501
• /
• 2002

A difference based current transformer (CT) saturation detection algorithm uses the third difference of a secondary current to detect the instants of the beginning/end of saturation. The third difference of a secondary current contains high frequency components when a CT is saturated. Thus, an effect of an anti-aliasing lowpass filter implemented in digital protection relays on the detection algorithm should be studied. This paper describes performance analysis of a lowpass filter on the CT saturation detection algorithm. The cutoff frequency of the lowpass filter is normally set to be half of a sampling frequency. In this Paper, two sampling frequencies of 3,840 (Hz) corresponding to 64 sample/cycle (s/c) and 1,920 (Hz) corresponding to 32 (s/c) are studied; the cutoff frequencies of the lowpass filters are set to be 1,920 (Hz), 960 (Hz) and 960(Hz), 480(Hz), respectively. And the proposed algorithm is verified by experiment. A 2nd order Butterworth filter is designed as a lowpass filter. The test results and experiment results clearly indicate that the saturation detection algorithm successfully detects the instants of the beginning/end of saturation even though a secondary current is filtered by the designed lowpass filters.

• 한국소음진동공학회논문집
• /
• 제12권9호
• /
• pp.717-724
• /
• 2002

In this study, a numerical analysis for the piston secondary dynamics of small refrigeration reciprocating compressors is performed. In general, the length of cylinder in this class of compressors is shortened to diminish the frictional losses of the piston-cylinder system. So, the contacting length between piston and cylinder wall is in variable with the rotating crank angle around the BDC of the reciprocating piston. In the problem formulation of the piston dynamics, the change in bearing length of the piston and all corresponding forces and moments are considered in order to determine the piston trajectory, velocity and acceleration at each step. A Newton-Raphson procedure was employed in solving the secondary dynamic equations of the piston. The developed computer program can be used to calculate the entire piston trajectory and the hydrodynamic force and moment as functions of crank angle under compressor running conditions. The results explored the effects of the radial clearance, lubricant viscosity, length of the cylinder wall, and pin location on the stability of the piston.

• 한국자동차공학회논문집
• /
• 제21권5호
• /
• pp.151-156
• /
• 2013

The experiment was done on cars travelling at the speeds of 20km/h, 60km/h and 100km/h using the performance testing mode for chassis dynamometer. In this experiment, the relativity between the secondary waveform coming from ignition coil and exhaust emissions were measured in case of cars with failures, in oxygen sensor, spark plugs. The following results obtained by analysis of the relativity between the secondary waveform and exhaust emissions. 1) When the oxygen sensor is failure, the average value of CO emission measured was 6.8 times higher than the standard CO emission value and the average value of HC emission measured was 2.3 times higher than the standard emission level. 2) When engine parts are in failure, more fuel enters the cylinder due to longer opening duration of injector, and it tended to make CO and HC emission values increase. 3) Combustion duration, the shape of flame propagation during spark line, and the size of the discharge-induced energy were the three main elements that directly cause variations in CO and HC emission values.

• 한국과학교육학회지
• /
• 제22권3호
• /
• pp.517-524
• /
• 2002

이 연구에서는 중등 과학 교사의 교사 연수 프로그램에 대한 요구와 오프라인 교육과 온라인 교육 중 선호하는 교육 방법을 조사하였다. 전국 106개 중등 학교의 과학 교사 145명을 대상으로 설문을 실시하였다. 과학 교사들은 모든 교육 내용에 대하여 전반적으로 높은 교육 요구를 보였다. 학생들의 학습 동기를 유발하는 방법에 대한 요구가 가장 높았던 반면, 과학사 및 과학 철학 분야에 대한 요구가 가장 낮았다. 숙련 교사와 고등학교 교사의 경우 평가 문항 제작에 대한 요구가 높았고, 비숙련 교사는 자신의 수업에 대한 효과성 평가 방법이나 과학에 대한 새로운 지식에 대한 요구가 높았다. 교육 방법의 측면에서는 실험 활동을 제외한 대부분의 교육 내용에 대하여 온라인 교육을 선호하였다.

• 전산구조공학
• /
• 제9권3호
• /
• pp.115-123
• /
• 1996

배관을 구속시키기 위한 원통형 배관 지지대(Trunnion Pipe Support)가 부착된 배관의 응력해석을 위하여 유한요소해석을 사용하였다. 해석결과로 부터 얻어진 응력은 두께에 대한 평균(막응력) 및 선형 응력(굽힘응력)으로 분류되었으며, 분류된 응력값은 압력에 에 의한 일차응력계수(B/sub 1/)와 이차응력계수(C/sub 1/), 모멘트에 의한 일차응력계수(B/sub 28/, B/sub 2T/)와 이차응력계수(C/sub 28/, C/sub 2T/)를 추정하기 위하여 ASME Code에 정의된것과 일치하게 해석되었다. 무차원의 함수로써 응력계수에 대한 경험식을 개발하기 위하여 여러 모델의 해석을 수행하였다.

• 한국컴퓨터정보학회:학술대회논문집
• /
• 한국컴퓨터정보학회 2018년도 제58차 하계학술대회논문집 26권2호
• /
• pp.244-247
• /
• 2018

본 연구는 우리나라 중등교사 임용시험의 형태가 개편된 2014년도 이후부터 2018년도 현재까지 진행된 중등교사 임용시험 관련 선행연구들을 언어네트워크 분석 방법론을 활용하여, 그 연구동향을 분석하였다. 본 연구에서는 2014년도 이후 5년간 진행된 중등교사 임용시험 관련 연구 55건을 대상으로 주요 핵심어 추출 및 워드클라우드 제시, 주요 핵심어의 언어네트워크 전체 분석 및 3종 중심성(연결정도, 근접, 매개) 분석, 네트워크 값을 반영한 네트워크 그림 시각화 작업 등을 진행하였다. 중등교사 임용시험 관련 선행연구의 주요 핵심어는 분석, 문항, 출제, 인식, 임용후보자, 교과교육학, 국어과, 선정경쟁시험, 개선, 예비교사, 교과내용학, 기출문항, 임용교사, 제도, 탐색 등이었다. 이들 상위 빈도 핵심어들은 나름 높은 연결정도를 가지고 다른 핵심어들간의 의미연결망을 구축하고 있음을 확인하였다, 이런 연구결과는 중등교사 임용시험 주제 연구 진행을 할 때, 연구주제 선정 및 방향 설정에 도움을 줄 것으로 기대된다.

• Journal of Microbiology and Biotechnology
• /
• 제23권7호
• /
• pp.932-941
• /
• 2013

This work aimed to classify Aspergillus (8 species, 28 strains) by using a secondary metabolite profile-based chemotaxonomic classification technique. Secondary metabolites were analyzed by liquid chromatography ion-trap mass spectrometry (LC-IT-MS) and multivariate statistical analysis. Most strains were generally well separated from each section. A. lentulus was discriminated from the other seven species (A. fumigatus, A. fennelliae, A. niger, A. kawachii, A. flavus, A. oryzae, and A. sojae) with partial least-squares discriminate analysis (PLS-DA) with five discriminate metabolites, including 4,6-dihydroxymellein, fumigatin, 5,8-dihydroxy-9-octadecenoic acid, cyclopiazonic acid, and neosartorin. Among them, neosartorin was identified as an A. lentulus-specific compound that showed anticancer activity, as well as antibacterial effects on Staphylococcus epidermidis. This study showed that metabolite-based chemotaxonomic classification is an effective tool for the classification of Aspergillus spp. with species-specific activity.

• 대한가정학회지
• /
• 제26권3호
• /
• pp.109-124
• /
• 1988

The purpose of the present study was to set up the basic outline to define and to develop "housing education" in the field of home economics education. The main focus included in the present study was to suggest the basic data on the current status of housing education in Korea by examining the content of the textbooks and the secondary data o teacher's educational background. The methods used in the study were the contentanalysis of the elementary school curriculum and the secondary data analysis of the data on teachers and their education. The results of this study ere on follows, 1. The elementary school curriculum defined as the related fields of housing education were classified into 4 domains: housing planning, housing maintenance, housing environment, housing decoration. 2. The subject areas related to housing education was found to be moral education, social education, physical education, art, practical education. The total hours studying on housing education were the average of 1.1 hours per week. 3. Among the above 4 domains, the total hours used for housing decoration amounted to the highest rate through all the subject areas. 4. According to the secondary dta analysis, 49.5% of the teacher were the national teacher's college graduates, but there are no courses on housing education as such in the curriculum of the national teacher's college. it was concluded that more consideration should be given to the teacher training courses.