• Journal of the Korean earth science society
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• v.34 no.4
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• pp.356-367
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• 2013

We study on the concept and reason of seasonal change that 164 university students have. Subsequently the concept types on the seasonal change are classified according to the characteristics and conceptual change after teaching on astronomy. All of the students were simply checked by the questionnaire of multiple choice and essay method before learning on the subjects. And then they answered to questionnaires of similar type after one semester. By the analyzed results, we classify it to three steps of hierarchical concept structure. The first step is the cosmic perspective that is related to the Earth's condition and motion. The second step is the influence of the Earth that is directly affected by the first step. The third step is observer's perspective on the Earth depending on the second step. Among the answers, the first step is prominent and second step is rare. The answers on the reason of seasonal change show some kinds of type which are 1st, 1-2nd, 1-3rd, and 1-2-3rd step. By the result, it is arranged in sequence like as 1-3rd>1st>1-2nd>1-2-3rd type. The lowest number of students was 2nd step of the Sun's altitude and duration of daytime in pre-test. However the students of 2nd step obtained more correct scientific concept on the seasonal change after learning on the subjects, and got the higher score in the post-test than in the pre-test. We found how much important the hierarchical structure on the reason of seasonal change is. As the results, second step on the learning of the Sun's altitude and duration of daytime essentially have to teach after first step. And then third step have to teach. At last, it is sure that the students can obtain the concept of seasonal change.

• Journal of Sericultural and Entomological Science
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• v.16 no.1
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• pp.77-84
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• 1974

In autumn season residual period of nicotine is observed in the larval duration, weight of molting larvae at the various stages, percentage of delayed molting larvae, and survival rate up to the 3rd stage from the 1st season to the 3rd season and up to the stage for four seasons, respectively. Mulberry tree is planted in pot from June 18, 1973 to August 4, 1973 and placed every other row between tobacco variety of Hicks cultivated in mulching system and control is prepared in the Sericultural Experiment Station, placing in the every ridge of mulberry field with the four seasons ; 5 day isolation (1st season), 15 day isolation (2nd season), 25 day isolation (3rd season), and 50 day isolation (4th season). 1) 1st and 3nd instar larvae fed with the tobacco stained mulberry leaf has longer larval duration for the four seasons, as compared with those of the control, increasing 12％ in index with 28 hours, 17％ in index with 37 hours, 23％ in index with 50 hours, 17％ in index with 43 hours from the 1st season to the fourth season and the 3rd to the 4th instar larvae, increasing 18％ in index with 55 hours. 2) 2nd instar molting larvae, 3rd instar molting larvae from the 1st to the 4th season and 4th instar molting larvae at the 4th season decrease their larval weight respectively, as compared with the control. 3) Percentage of delayed molting larvae from the 3rd stage to the 4th stage goes up higher than that of the control in the End larval stage at the 3rd to the 4th season, in the 3rd larval stage at the 1st, the End, and the 4th season, and in the 4th larval stage at the 4th season, respectively. 4) Survival rates in the 2nd larval stage at the 2nd season to the 4th season, in the 3rd larval stage at the 1st to the 4th season, and in the 4th larval stage at the 4th season respectively are higher than that in the control.

• Review of Korea Contents Association
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• v.15 no.4
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• pp.28-32
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• 2017

• 전기의세계
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• v.68 no.3
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• pp.27-30
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• 2019

• International Commerce and Information Review
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• v.18 no.4
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• pp.285-310
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• 2016

The purpose of this study empirically verified impact of strategic and operational integration between first-tier supplier and their supplier and strategic and operational integration between first-tier supplier and their buyer on operation performance. In order to achieve our goal, we tested reliability, validity and path coefficient using structural equation modeling-partial least square (SEM-PLS) over 284 first-tier manufacturing suppliers data that Korea Productivity Center (KPC) surveyed in 2013. This study results indicated that operational integration between first-tier supplier and their supplier or buyer has positive impact on production process flexibility. Meanwhile, strategic integration between first-tier supplier and buyer has positive impact on production flexibility. On the other hand, strategic integration between first-tier supplier and supplier has negative impact on production flexibility. And production process flexibility has positive impact on production flexibility. By empirically testing to departmentalize level and scope of supply chain integration, this study has academic and managerial implications from first-tier perspective on.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.1 s.104
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• pp.67-73
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• 2006

This paper proposes a new predistortion linearizer with controlling intermodulation distortion(IMD) signals. This linearizer achieves independent control of third- and fifth-order intermodulation distortion products using amplitude modulation with even harmonic signals. A vector modulator that modulate fundamental signal with both second- and fourth-order harmonic components generated by harmonic generator circuits, generates the inverse characteristics third-and fifth-order intermodulation signals of power amplifier and controls amplitude and phase of them with each other modulation factors. As a results, this linearizer is suppressed IMD signals of power amplifier effectively. The test results show that the third IMD is cancelled more than 25 dB and the fifth order IMD is cancelled about 18 dB for CW two-tone signals. Also, it's improved the adjacent channel power ratio(ACPR) more than 7 dB for IS-95 CDMA signals.

• Proceedings of the Korean Society of Community Living Science Conference
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• 2009.09a
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• pp.85-85
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• 2009

차는 세계에서 가장 오랜 역사를 가지고 있는 음료로 건강에 대한 관심증가와 함께 음용량이 꾸준히 증가하는 추세이다. 그러나 국내 차 산업은 중국이나 일본 등에 비해 가격 품질경쟁력, 상품개발 면에서 크게 뒤떨어져 있는 실정이며, 향후 차시장도 전면적인 시장개방의 위협에 직면해 있어 차 산업의 발전을 위해서는 경쟁력 있는 수출전략과 함께 국내산업 유지를 위한 전략도 모색해야 한다. 본 연구는 차 소비자의 구매 선택속성을 분석한 것이다. 수도권에 거주하는 20세 이상 남녀 소비자를 대상으로 총 220부의 질문지를 배부하여 최종적으로 189부를 분석하였다. 전체 조사대상자는 여자가 155명(82.0%)이었으며, 연령은 20대가 29명(15.3%), 30대가 52명(27.5%), 40대가 56명(29.6%), 50대 이상은 52명(27.5%)이었다. 교육수준은 대학교졸/재가 91명(48.2%), 으로 가장 많은 비율을 차지했으며, 직업은 회사원/공무원이 59명(31.2%), 주부가 59명(31.2%)으로 가장 많은 비율을 차지했다. 월평균 소득은 200만원~300만원 미만이 57명(30.2%)으로 가장 많은 비율을 차지했다. 조사대상자의 차 소비 특성으로는 잎차와 티백, 가루차를 포함해 연평균 차 구매량이 '1~3통'이라고 응답한 사람이 73명(38.6%)으로 가장 높게 나타났고, '4~6통'이 39명(20.6%), '1통 미만'이 32명(16.9%), '6~10통'은 24명(12.7%), '10통 이상'은 21명(11.1%)으로 나타났다. 차를 마시는 장소는 '사무실이나 학교'가 100명(52.9%)으로 가장 높게 나타났으며, '집'은 83명(43.9%), '녹차전문점이나 찻집'은 6명(3.2%)으로 나타났다. 차를 마시는 상황은 '혼자 마신다'가 72명(38.1%)으로 가장 높게 나타났다. '친구와 만날 때나 사교모임 시'는 68명(36.0%), '가족과 함께 대화 시'는 31명(16.4%), '사업상대를 만날 때'는 18명(9.5%)으로 나타났다. 차를 음용하는 이유는 '편안한 대화를 하는데 도움이 되기 때문'이 65명(34.4%)으로 가장 높게 나타났고, '건강에 좋은 웰빙 음료이기 때문'은 53명(28.0%), '기호음료로서 맛과 향이 좋기 때문'은 42명(22.2%), '정신을 맑게 해주기 때문'은 21명(11.1%), '갈증해소에 좋기 때문'은 8명(4.2%)으로 나타났다. 차 구입 시 정보를 얻는 곳은 '주위사람들'이 77명(40.7%)으로 가장 높았고, '신문이나 잡지, TV 등'은 66명(34.9%), '판매원이나 시음을 통해서'는 33명(17.5%), '인터넷'이 13명(6.9%)으로 나타났다. 차소비자들이 가장 중요하게 여기는 속성은 맛(4.31)이 가장 높게 나타났으며, 그 다음이 향(4.12), 브랜드(3.84), 가격(3.76), 생산지역(3.75), 발효정도(3.72), 색(3.68), 채엽시기(3.69), 포장(3.66), 제조방법(3.56) 순으로 나타났다.

• Geophysics and Geophysical Exploration
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• v.5 no.3
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• pp.199-205
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• 2002

In the resistivity method, the potential difference between two grounded electrodes is measured and this can be positive or negative. The apparent resistivity and the potential difference have the same polarity. Since the electric field is the gradient of the potential, the polarity of the potential difference depends on the direction of the electric field. If the direction of the vector connecting two grounded electrodes is the same to that of the electric field, the measured potential difference and the apparent resistivity become positive. If the opposite is the case, they become negative. In general, the primary electric field and the vector connecting two potential electrodes have the same direction in a surface resistivity method. In this case, the measured potential difference is always positive because the primary electric field is greater than the secondary field. Therefore, the apparent resistivity is always positive if noise is free and topography is flat. The secondary field component, however, can be greater than the primary field component along the vector connecting two potential electrodes in the cross-hole resistivity method. Furthermore, if the secondary electric field and the vector connecting two potential electrodes have an opposite direction, the apparent resistivity become negative. Consequently, the apparent resistivity may be negative in the region where the primary electric field component along the vector connecting two potential electrodes is very small.

• Communications of Mathematical Education
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• v.32 no.1
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• pp.79-96
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• 2018

The purpose of this study was to compare and analyze changes to the middle school mathematics textbooks of third mathematics curriculum period and seventh mathematics curriculum period. This study put the math curricula from the third to the sixth one in third mathematics curriculum period as those math curricula witnessed the maintenance of industrial society paradigm. And then it put the math curricula from the seventh one to current the 2009 revised mathematics curriculum in seventh mathematics curriculum period as the knowledge-based information society paradigm has continued throughout those math curricula. Based on those period categories, We compared and analyzed changes of the middle school math textbooks. For the comparison and analysis of math textbooks between the two periods, this study set the unit organization system, unit goal, task type and content development approach as analysis elements in the unit of 'Nature of Figures' in the second grade math textbooks for middle school. As a result of the research, it was confirmed that the textbooks of the two periods had many changes in the unit organization system, but the unit goal, task type, and content development approach stayed in low level goals and task type that require conceptual and procedural.

• Korean Journal of Soil Science and Fertilizer
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• v.39 no.5
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• pp.307-314
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• 2006

Elevation differences within a paddy field relate strongly to plant health, crop homogeneity, and pest control. For precision agriculture (PA), the elevation within a field should be precisely controlled. We analyzed variation in elevation within two rice paddies over one crop cycle. The study took place in two rectangular plots (Field A and Field B, each $50m{\times}30m$). Elevations within the two plots were measured by a laser-equipped surveying instrument, that could determine elevations to precisions of 1 mm. The test fields were divided into grids with 30 squares; elevation was measured at the center of each $5{\times}10-m$ grid square. This study measured elevation during nine observation periods from pre-plowing to post-harvest. Descriptive statistics showed the highest elevations after plowing due to soil disturbance. One-way analysis of variance (ANOVA) revealed significant elevation differences before and after plowing and transplanting, although elevations were similar over the period of crop growth. Comparison of pre-plowing and post-harvest data showed differences in elevations, indicating that elevation changes occurred during plowing, rice transplanting, plant growth, and harvesting. In summary, the above statistical analyses indicated that elevation changes occurred due to plowing but not during the plant growth season or due to harvesting.