• Journal of Elementary Mathematics Education in Korea
• /
• v.17 no.1
• /
• pp.143-164
• /
• 2013

Despite the recent emphasis on mathematical communication, little practical guide has been provided for a teacher with what to do for orchestrating high-quality discussions in a mathematics classroom. This paper analyzed 20 elementary mathematics lessons which were recognized as effective instruction in Korea using an analytic framework with regard to 5 practices for orchestrating productive mathematics discussions (i.e., anticipating, monitoring, selecting, sequencing, & connecting) by Smith and Stein (2011) in terms of performance scales from Level 0 to 3. The results of this study showed that the most frequent levels were Level 1 including undesirable practices and Level 2 including insufficient practices. There were only one or two lessons per practice which were assessed as Level 3 of good performance. Specifically, Level 2 was the most frequent with regard to monitoring and selecting, whereas Level 1 was the most frequent as for the other practices. This paper provides some implications for co-ordinating productive mathematics discussions.

• Education of Primary School Mathematics
• /
• v.25 no.4
• /
• pp.433-457
• /
• 2022

An effective teacher community helps the participating teachers improve their instructional quality. This study reports a teacher community consisting of 15 elementary school teachers and one teacher educator. This paper analyzed 15 mathematics lessons in which the teachers implemented the five practices for orchestrating productive mathematics discussions by Smith and Stein (2018) based on the grade-specific discussions as well as the whole community's discussions. The results of this study showed that the overall levels of each practice either increased gradually or maintained at the highest Level 4, as mathematics lessons had been implemented. Specifically, the following practices were quite successful: setting goals for a lesson, selecting an appropriate task, anticipating student responses, and selecting student solutions. However, both sequencing and connecting student solutions were implemented at various levels. Monitoring student work tended to remain at Level 2 which included incorrect implementation of the practice. This paper closes with implications related to the skillful implementation of the five practices through a teacher community.

• Korean Journal of Plant Resources
• /
• v.10 no.4
• /
• pp.397-400
• /
• 1997

The experiment was carried out to determine the optimum fertilization level showing high quality on Aralia cordata Thunb. Plant height of fertilization(27-15-27kg) was promoted significantly compared with conventional fertilization(17-9-17kg). This effect was followed with increment of blanched length. Among underground parts, main root length was increased in conventional fertilization, and more cultural year was prolonged, the more yield of dry root weight was increased. Fresh leaf yield to produce high quality of Aralia cordata plant was remarkably increased about 6% in fertilization of 27-15-27kg per 10a. As a result, to produce higher good quality of the plant. the optimum fertilization level was 27-15-27kg per 10a.

• The Mathematical Education
• /
• v.62 no.1
• /
• pp.95-115
• /
• 2023

Even the teachers who agree with the necessity of effective mathematical discussions find it difficult to orchestrate such discussions in the actual lessons. This study focused on analyzing the difficulties 15 elementary school teachers faced in applying "the five practices for orchestrating productive mathematics discussions" to their lessons. Specifically, this study analyzed the process of planning, implementing, and reflecting on the lessons to which three or four teachers as a teacher community applied the five practices. The results of this study showed that the teachers experienced difficulties in selecting and presenting tasks tailored to the student levels and class environment, monitoring all students' solutions, and identifying the core mathematical ideas in student solutions. In addition, this study revealed practical and specific difficulties that had not been described in the previous studies, such as writing a lesson plan for effective use, simultaneously performing multiple teacher roles, and visually sharing student presentations. This study is expected to provide practical tips for elementary school teachers who are eager to promote effective mathematical discussions and to provoke professional discourse for teacher educators through specific examples.

• Proceedings of the Korean Society of Organic Agriculture Conference
• /
• 2005.12a
• /
• pp.37-45
• /
• 2005

본 시험은 관행(일반)과 유기조사료 생산에서 여름 사료작물인 옥수수, 수수 및 수단그라스의 생산량과 생산비를 비교하기 위하여 실시하였다. 관행(일반)생산에 옥수수, 수수 및 수단그라스의 건물수량은 각각 14,265 kg/ha, 23,780 kg/ha 및 20,867kg/ha로 옥수수에 비하여 수수는 67%, 수단그라스는 46% 수량이 많았다. 관행 옥수수, 수수 및 수단그라스의 ha당 생산비는 3,167,346원, 2,579,545원 및 2,696,298원이었으며, 건물 1kg 생산비는 관행 옥수수, 수수 및 수단그라스가 각각 222원, 110원 및 131원으로 옥수수의 생산비가 수수보다 2배 많이 소요되었다. 그리고 생산비 중에서 가장 많은 비중을 차지하는 것은 지대(땅값)로 35.3%에서 37.6%를 차지하였으며, 다음은 비료(퇴비포함), 노동력 순으로 나타났다. 유기조사료 생산에서 옥수수, 수수 및 수단그라스의 건물수량은 각각 8,965 kg/ha, 17,719 kg/ha 및 15,260kg/ha로 옥수수에 비하여 수수는 98%, 수단그라스는 70% 수량이 많았다. 유기 옥수수, 수수 및 수단그라스의 ha당 생산비는 2,989,327원, 2,593,082원 및 2,660,894원이었으며, 건물 1kg 생산비는 유기 옥수수, 수수 및 수단그라스가 각각 334원, 149원 및 176원으로 옥수수의 생산비가 수수보다 2배 이상 많이 소요되었다. 그리고 유기 여름사료작물의 생산비 중에서 가장 많은 비중을 차지하는 것은 관행과 마찬가지로 지대(땅값)였으며, 다음은 퇴비생산, 노동력 순으로 나타났다. 관행 및 유기 여름사료작물의 생산량 비교에서 관행이 유기보다 건물수량은 5,656 kg/ha, TDN 수량은 3,531 kg/ha 많았다. 한편 관행 및 유기 여름사료작물의 생산비에서는 면적당 생산비는 관행이 많았으나 건물 TDN 1kg 당 생산비는 유기 여름사료작물이 관행보다 건물은 66원, TDN은 100원 많이 소요되었다. 이상의 연구결과를 종합해볼 때 관행 생산 여름 사료작물이 유기생산보다 생산량과 단위면적당 생산비는 많았으나 kg당 생산비는 유기 생산이관행보다 많이 소요되었다. 생산비 중에서 가장 많은 비중을 차지한 것은 지대(땅값)였으며, 다음은 퇴비와 노동력이 가장 많은 비중을 차지하여 농가의 낙농경영에 가장 어려운 문제는 땅값, 퇴비생산, 노동력으로 평가되었다.

• Korean Journal of Organic Agriculture
• /
• v.15 no.2
• /
• pp.207-218
• /
• 2007

Coming with the well-being era, consumer's demand for safe agricultural products is increasing. So, it is urgent to develop an environment-friendly rice production system. Accordingly, this study was conducted to develop an environment-friendly rice production system by using Amo known as EM(effective microorganisms) and also known as being effective in environment-friendly rice production with several other environment-friendly agricultural materials. The highest number of tillers per hill was obtained from level 2 of EM treatment (48.8 tillers per hill), while the lowest was obtained from the control plot (41.0 tillers per hill). Leaf area per hill at heading stage was the highest in level 3 of EM treatment $(3228.5cm^2)$, while control was the lowest leaf area $(2264.7cm^2)$, which is 70.2% compared to the level 3 of EM treatment. The highest effective tillers was obtained from the control (63.7%), while the lowest effective tillers was obtained from the level 3 of EM treatment (55.4%), which were treated with higher amounts of environment-friendly agricultural materials. Level 3 of EM treatment showed the highest number of panicles per hill (20.9), while the control showed the lowest number of panicles per hill (19.3). In the spikelets per panicle, level 2 of EM treatment showed the highest number of spikelets (85.2), while the control showed the lowest number of spikelets (81.9) and there was a statistically significant difference among the three levels and control. The highest grain filling ratio was obtained from the control (85.0%), while level 3 of EM treatment was the lowest grain filling ratio and there were no great difference between treatment levels. Regarding the 1000 grain weight, the control showed the highest 1000 grain weight (21.7g), which is heavier by about 1g compared to treatment levels. Level 2 of EM treatment showed the highest rough rice yield per 10a, while level 3 of EM treatment was the lowest and they also showed a statistically significant difference among treatment levels.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.26 no.4
• /
• pp.311-317
• /
• 1981

As the low labor-productivity is being floated up to be the most limiting factor in barley cropping, the endeavor of many researchers concerned have been concentrated on recovering from that. For this reason, in this experiment 8 kinds of sowing methods were employed to survey the yield productivity and the labor-requirement of each methods. And with promising the possibility of consistent mechanization, both prediction of the assurable requirement of labor investment and calculation of the labor productivity in each method were estimated so that the possibility of labor-saving in barley cultivation investigated. Also sowing methods for labor-saving cultivation were presented according to the labor-structure of farm as divided with the phases.

• Journal of Bio-Environment Control
• /
• v.21 no.1
• /
• pp.1-11
• /
• 2012

The objective of the present study is to provide data needed to find double covering method to be able to improve environment of temperature, humidity and PPF in tomato greenhouse. The distribution charts of temperature, humidity and PPF which were measured in environment control conditions such as thermal insulation, air heating, roof ventilation and air fog cooling in conventional and air inflated double layers greenhouses were drawn and analysed. The thermal insulation effect of the air inflated greenhouse was the same as that of conventional greenhouse because the temperature between insulation curtain and roof covering material was equal in heating season. The ventilation effect of the air inflated greenhouse was superior to the conventional greenhouse. The temperature distribution in the fog cooled greenhouse was uniform and the cooling effect was about $3.5^{\circ}C$. The condensation on the roof covering surface could be controlled by removing the moisture between insulation curtain and roof covering by using humidifier. The PPF of conventional greenhouse was more decreased than the air inflated greenhouse as time went by because the transmittance of conventional greenhouse declined by dust collected on the inside plastic film owing to rolling up and down operation for ventilation.

• Korean Journal of Weed Science
• /
• v.15 no.2
• /
• pp.105-114
• /
• 1995

Differences in critical period of weed competition were investigated among five types of rice(Oryza sativa L.) cultivation. Increase in weed-free period resulted in 1-2 days delay of heading date in machine transplanting and direct-seeding as compared with complete weed-free plot. When weedy period increased, there was no difference in heading date in transplanting cultivations. In direct-seeding, however, weedy period of 7-10 weeks after seeding(WAS) resulted in 4-7 days delay of heading date, whereas further increase in the weedy period caused rather 5-6 days advance in heading date. Weed-free period did not significantly affect yield components in conventional hand transplanting. In machine transplanting with 30-day-old seedling decreases in percent ripening and 1,000-grain weight were caused by weeds emerged within 4 weeks after transplanting(WAT). All yield components were decreased due to weedy period in machine transplanting with 10-day-old seedling. In direct-seeding weedy periods caused to decrease in number of panicles, number of spikelets, percent ripening, and 1,000-grain weight were 8-9, 4-5, 3-4, and 8-10 WAS, respectively. The critical periods of weed competition were determined as the following. In conventional hand transplanting weed-free must be maintained for either 4 weeks after transplanting or the rest period after 8 WAT. In machine transplanting with 30-day-old seedling weed-free must keep for either 5 weeks after transplanting or the rest period after 8 WAT. In machine transplanting with 10-day-old seedling weeds must be removed for either 5 weeks after transplanting or the rest period after 7 WAT. Weed-free must be kept between 5 and 7 WAS in flood direct-seeded rice and between 6 and 9 WAS in dry direct-seeded rice.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.42 no.2
• /
• pp.166-172
• /
• 1997

This experiment was carried out to clarify the effect of the deep water irrigation on dry-seeded rice cultivation at the three different water managements-deep continuous flooding(DCF), water saving irrigation(WSI), ordinary irrigation(OI). The highest tillering numbers per $m^2$ of rice were 551, 466 and 455 in OI, WSI and DCF, respectively. The tillering number of rice plants were significantly reduced in DCF. Heading date was delayed and the total chlorophyll content in leaf after heading was higher in DCF than those in other irrigation methods. For the characteristics associated with lodging, the culm length in DCF was slightly elongated and the diameter of culm in DCF was thicker than that in WSI and OI. The breaking weight and bending moment in DCF also were higher than those in others. As the result, although the culm length in DCF was long, the lodging index was comparatively low. The panicle length in DCF was longer than in OI and WSI. The spikelet number per $m^2$ and 1,000-grain weight were the most in WSI, while panicle number, ripened grain ratio and grain weight were not significantly different. Longer panicle length and more spikelet number resulted in higher yielding capacity in DCF.