• Journal of The Korean Association For Science Education
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• v.15 no.2
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• pp.173-184
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• 1995

The purpose of this study was to analyse the problems of 'Science Inquiry Experiment Contest(SIEC)' which was one of 8 programs of 'The 2nd Student Science Inquiry Olympic Meet(SSIOM)'. The results and conclusions of this study were as follows: 1. It needs to reconsider the role of practical work within science experiment because practical work skills form one of the mainstays in current science. But the assessment of students' laboratory skills in the contest was made little account of. It is necessary to remind of what it means to be 'good at science'. There are two aspects: knowing and doing. Both are important and, in certain respects, quite distinct. Doing science is more of a craft activity, relying more on craft skill and tacit knowledge than on the conscious application of explicit knowledge. Doing science is also divided into two aspects, 'process' and 'skill' by many science educators. 2. The report's and checklist's assessment items were overlapped. Therefore it was suggested that the checklist assessment items were set limit to the students' acts which can't be found in reports. It is important to identify those activities which produce a permanent assessable product, and those which do not. Skills connected with recording and reporting are likely to produce permanent evidence which can be evaluated after the experiment. Those connected with manipulative skills involving processes are more ephemeral and need to be assessed as they occur. The division of student's experimental skills will contribute to the accurate assess of student's scientific inquiry experimental ability. 3. There was a wide difference among the scores of one participant recorded by three evaluators. This means that there was no concrete discussion among the evaluators before the contest. Despite the items of the checklists were set by preparers of the contest experiments, the concrete discussions before the contest were necessary because students' experimental acts were very diverse. There is a variety of scientific skills. So it is necessary to assess the performance of individual students in a range of skills. But the most of the difficulties in the assessment of skills arise from the interaction between measurement and the use. To overcome the difficulties, not only must the mark needed for each skill be recorded, something which all examination groups obviously need, but also a description of the work that the student did when the skill was assessed must also be given, and not all groups need this. Fuller details must also be available for the purposes of moderation. This is a requirement for all students that there must be provision for samples of any end-product or other tangible form of evidence of candidates' work to be submitted for inspection. This is rather important if one is to be as fair as possible to students because, not only can this work be made available to moderators if necessary, but also it can be used to help in arriving at common standards among several evaluators, and in ensuring consistent standards from one evaluator over the assessment period. This need arises because there are problems associated with assessing different students on the same skill in different activities. 4. Most of the students' reports were assessed intuitively by the evaluators despite the assessment items were established concretely by preparers of the experiment. This result means that the evaluators were new to grasp the essence of the established assessment items of the experiment report and that the students' assessment scores were short of objectivity. Lastly, there are suggestions from the results and the conclusions. The students' experimental acts which were difficult to observe because they occur in a flash and which can be easily imitated should be excluded from the assessment items. Evaluators are likely to miss the time to observe the acts, and the students who are assessed later have more opportunity to practise the skill which is being assessed. It is necessary to be aware of these problems and try to reduce their influence or remove them. The skills and processes analysis has made a very useful checklist for scientific inquiry experiment assessment. But in itself it is of little value. It must be seen alongside the other vital attributes needed in the making of a good scientist, the affective aspects of commitment and confidence, the personal insights which come both through formal and informal learning, and the tacit knowledge that comes through experience, both structured and acquired in play. These four aspects must be continually interacting, in a flexible and individualistic way, throughout the scientific education of students. An increasing ability to be good at science, to be good at doing investigational practical work, will be gained through continually, successively, but often unpredictably, developing more experience, developing more insights, developing more skills, and producing more confidence and commitment.

• Asian-Australasian Journal of Animal Sciences
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• v.23 no.4
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• pp.521-529
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• 2010

Two experiments were conducted to evaluate multi-microbe submerged liquid (SLF) and solid substrate (SSF) fermented probiotic products in broilers. The SLF and SSF probiotics were comprised of Lactobacillus acidophilus ($1.1{\times}10^9$ and $4{\times}10^8$ cfu/g), Bacillus subtilis ($1.1{\times}10^9$ and $4{\times}10^9$ cfu/g), Saccharomyces cerevisiae ($1.5{\times}10^7$ and $1.0{\times}10^4$ cfu/g) and Aspergillus oryzae ($2.6{\times}10^7$ and $4.3{\times}10^7$ cfu/g), respectively. In Exp. 1, 640 day-old Ross chicks were allotted to 4 treatments, each comprising 4 replicates (40 chicks/replicate). The basal diet was prepared without any antimicrobials (negative control, NC), and 20 mg/kg avilamycin (positive control, PC), 0.3% SLF and 0.3% SSF probiotics were added to the basal diets as treatments. Birds fed PC and SSF diets showed improved (p<0.001) overall weight gain and F/G than birds fed NC and SLF diets; whereas, birds fed SLF diet had better weight gain and F/G than birds fed NC diet. Retention of CP was higher (p<0.05) in birds fed the SSF diet than birds fed PC, SLF and NC diets. Birds fed the SLF diet tended to have higher (p<0.10) cecal total anaerobic bacteria than birds fed PC and NC diets; whereas, lesser cecal coliforms were noticed in birds fed PC, SLF and SSF diets than birds fed the NC diet. In Exp. 2, 640 day-old Ross chicks were randomly allotted to 4 treatments in a $2{\times}2$ factorial arrangement. Each treatment had 4 replicates (40 chicks/replicate). Two different multi-microbe probiotic products (0.3% SLF or SSF) each with two different antibiotics (10 mg/kg colistin, or 20 mg/kg avilamycin) were used as dietary treatments. Birds fed the SSF diet had greater weight gain (p<0.001), better F/G (p<0.05), greater retention of energy (p<0.001) and protein (p<0.05), and lesser cecal Clostridium (d 35) than birds fed SLF diet. Birds fed the colistin-supplemented diet had less (p<0.01) cecal coliforms when compared with birds fed the avilamycin diet. Additionally, birds fed the avilamycin diet had greater energy retention (p<0.05) than birds fed the colistin diet. Thus, the results of this study suggest the multi-microbe probiotic product prepared by a solid substrate fermentation method to be superior to the probiotic product prepared by submerged liquid fermentation; moreover, feeding of probiotics with different antibiotics did not elicit any interaction effect between probiotic and antibiotic.

• Journal of Biosystems Engineering
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• v.2 no.1
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• pp.7-24
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• 1977

This paper is the forth and fifth one of the study on balanced type oscillating mole drainer. In the light of the results from previous reports about the model tests, some design criteria were established and a prototype machine was set up for experimental purpose. Motion characteristics and functionof the each parts of the machine were checked and analyzed. After that, performance tests of the prototype machine were carried out in thefield. Obtained results are summarized as follows ; 1. Ten centimeter of the bullet diameter was determined so as to be able to attach it to the tractors with capacity of 30 PS to 40 PS. 2. To maintain the balance between the moments of the front shank and rear shank, the oscillating amplitude of the rear bullet was determined to be larger than that of the front bullet. At the same time , the oscillating direction of the rear bullet was designed with the inclines of ten to thirty degrees. 3. An octagonal dynamo transduced was developed for measuring the compressive force of the upper link is measuring the draft force of the machine. Acceptable linear relationship between forces and strain responses from O.D.T. was obtained. 4. Analysing the balancing mechanism of the acting part of the machine , it was found that the total draft force of the machine was equal to the difference between the sum of the draft force produced from the right and left side bending moments of the lower drawber and the compressive force on the upper link. 5. There are acceptable linear relationship between the strain and twisting moment by driving shaft, and between strain and shank moment. Above results enable us to carry out the field experiment with prototype machine. 6. When the test machine was used in the field, it was possible to reduce the oscillating acceleration by forty percent in average as compared it with the single bullet mole drainer. 7. When the test machine was used under the oscillating condition, the dratt torce was reduced by 27 percent to 59 percent as compared it with the test machine under non-oscillating condition, while the draft force was increased by 7 percent to 20 percent as compared it with the mole drainer having oscillating single bullet. The reasoning behind this fact was considered as the resistance force due to the rear shank and bullet. 8. As the amplitude and frequency of the bullet were increased, the torque was increased accordingly. This tendency could be varied with the various characteristics of the given soils. And the larger frequency and amplitute, the more increasing oscil\ulcornerlating power but decreasing draft brce were needed, and draft force was increased as the velocity was increased.9. When the amplitude of the rear bullet was designed to be larger than that of the front bullet, the minimum value of the moment was lowered and oscillating acceleration was reduced. And when the oscillating direction of the rear bullet was declined back\ulcornerwards, oscillating acceleration was increased along with the increasing angle of decli\ulcornernation. When the test machine was operated in high speed, the difference between maximum moments and minimum ones became narrow. This varying magnitude of moments appeared on the moment oscillogram seems to be correlated to the oscillating acceleration and draft force. 10. From the analysis of variance, it was found that those factors such as frequency, amplitude, and operating velocity significantly affected in the oscillating acceleration, the draft resistance, the torque, the moment, and the total power required. And interaction between frequency and amplitude affected in the oscillating acceleration. 11. Within the given situation of this study, the most preferable operating conditions of the test machine were 7 Hz in oscillating frequency, 0.54 m/sec in operating velocity, and 39.1 mm in oscillating amplitude of front and rear bullets. However, it is necessary to select the proper frequency and magnitude of oscillation depending on the soil properties of the field in which the mole drainer is practiced by use of a bal1nced type oscillating mole drainer. 12. It is recommended that a comparative study of the mole drainers would be performed in the near future using two separate balanced oscillating bullet with the one which is operated by oscillating the movable bullet in a single cylinder or other balanced type which may be single oscillating bullet with spring, damper or balancing weight, and that of thing. To expand the applicability of the balanced type oscillating mole drainer in practical use, it is suggested to develop a new mechanism which perform mole drain with vinyl pipe or filling material such as rice hull.

• Communications of Mathematical Education
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• v.25 no.1
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• pp.99-118
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• 2011

For this case study of gifted education, two classrooms in two locations, show life in general of the gifted educational system. And for this case study the identity of teachers and the gifted, help to activate the mathematically gifted education for these research questions, which are as followed: Firstly, how is the gifted education classroom life? Secondly, what kind of identity do the teachers and gifted students bring to mathematics, mathematics teaching and mathematics learning? Being selected in the gifted children's education center solves the research problem of characteristic and approach. Backed by the condition and the permission possibility, 2 selected classes and 2 people, which are coming and going. Gifted education classroom life, the identity of teachers and gifted students in mathematics and mathematics teaching and mathematic learning. It will be for 3 months, with various recordings and vocal instruction between teacher and students. Collected observations and interviews will be analyzed over the course of instruction. The results analyzed include, social participation, structure, and the formation of the gifted education classroom life. The organization of classes were analyzed by the classes conscious levels to collect and retain data. The classes verification levels depended on the program's first class incentive, teaching and learning levels and understanding of gifted math. A performance assessment will be applied after the final lesson and a consultation with parents and students after the final class. The six kinds of social participation structure come out of the type of the most important roles in gifted education accounts, for these types of group discussions and interactions, students must have an interaction or individual activity that students can use, such as a work product through the real materials, which release teachers and other students for that type of questions to evaluate. In order for the development of meaningful mathematical concepts to formulate, mathematical principles require problem solving among all students, which will appear in the resolution or it will be impossible to map the meaning of the instruction from which it was formed. These results show the analysis of the mathematics, mathematics teaching, mathematics learning and about the identity of the teachers and gifted. Gifted education teachers are defined by gifted math, which is more difficult and requires more differentiated learning, suitable for gifted students. Gifted was defined when higher level math was created and challenged students to deeper thinking. Gifted students think that gifted math is creative learning and they are forward or passive to one-way according to the education atmosphere.

• Strategy21
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• s.32
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• pp.123-159
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• 2013

The purpose of this research paper is to re-valuate the factors that affected the Royal Navy's rearmament and preparation for war by conducting analysis on the discussion held in the Britain on the strategic priorities and Navy's coping measures adopted during the interwar period. After the end of the WWI, each of the military arms of the Britain faced significant difficulty in securing budget and increasing their military power all throughout the interwar period, and the Navy was not an exception. The WWII that got started on September 1939 was the turning point in which this difficulty led to full-fledged crisis. Immensely many criticisms followed after the war and problems were identified when it comes to the Royal Navy's performance during the war. This type of effort to identify problem led to the attempt to analyze whether Royal Navy's preparation for war and rearmament policy during interwar period were adequate, and to identify the root causes of failure. Existing studies sought to find the root cause of failed rearmament from external factors such as the deterioration of the Britain itself or pressure from the Treasury Department to cut the budget for national defense, or sought to detect problems from the development of wrong strategies by the Navy. However, Royal Navy's failed preparation for the war during interwar period is not the result of one or two separate factors. Instead, it resulted due to the diverse factors and situations that the Britain was facing at the time, and due to intricate and complex interaction of these factors. Meanwhile, this research paper focused on the context characterized by 'strategic selection and setting up of priorities' among the various factors to conduct analysis on the Navy's rearmament by linking it with the discussion held at the time on setting up strategic priorities, and sought to demonstrate that the Navy Department's inadequate counter-measures developed during this process waned Royal Navy's position. After the end of WWI, each of the military arms continued to compete for the limited resources and budget all throughout the interwar period, and this type of competition amidst the situation in which the economic situation of Britain was still unstable, made prioritization when it comes to the allocation of resources and setting up of the priorities when it comes to the military power build-up, inevitable. Amidst this situation, the RAF was able to secure resources first and foremost, encouraged by the conviction of some politicians who were affected by the 'theory of aerial threat' and who believed that curtailing potential attack with the Air Force would be means to secure national security at comparatively lower cost. In response, Navy successfully defended the need for the existence of Navy despite the advancement of the aerial power, by emphasizing that the Britain's livelihood depends on trade and on the maintenance of maritime traffic. Despite this counter-measuring logic, however, Navy's role was still limited to the defense of overseas territory and to the fleet run-off instead of sea traffic route production when it comes to the specific power build-up plan, and did not understand the situation in which financial and economic factors gained greater importance when it comes to the setting up of strategic priorities. As a result, Navy's plan to build its powers was met with continual resistance of the Treasury Department, and lost the opportunity to re-gain the status of 'senior service' that it had enjoyed in the past during the competition for strategic prioritization. Given that the strategic and economic situation that Korea faces today is not very different from that of the Britain during the interwar period, our Navy too should leverage the lessons learned from the Royal Navy to make the effort to secure viable position when it comes to the setting of priorities in case of national defense strategy by presenting the basis on why maritime coping should be prioritized among the numerous other threats, and by developing the measures for securing the powers needed effectively amidst the limited resources.

• Journal of the Korean Applied Science and Technology
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• v.37 no.4
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• pp.870-877
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• 2020

The purpose of this study is to compare and analyze the effects of stepping-in-place tempo and roundhouse kick types on response time. Fifteen males participated in this experiment. All have over ten years of experience and hold a forth dan(degree) black belt in taekwondo. The task is when the participants are doing stepping in place they respond to the light stimulus as fast as they can do roundhouse kick. Five different stepping in place tempos (100, 120, 140, 160, and 180 bpm) and four different types of roundhouse kick(front leg body roundhouse kick, front leg head roundhouse kick, back leg body roundhouse kick, and back leg head roundhouse kick) were used. Three measurements were taken for each of the different combinations of conditions for a total of 60 measurements. For data analysis, two-way ANOVA with repeated measures was used and pair-wise comparisons were performed using bonferroni statistics. The results show that there was significant difference interaction effect between stepping in place tempo and roundhouse kick type in the response time. And, there were significant difference in main effect of response time in accordance with stepping in place tempo and roundhouse kick type. The response time of roundhouse kick was the fastest at 160 bpm of stepping in place tempo, but there was no significant difference between 140 and 160 bpm. Front leg body roundhouse kick was the fastest. And, the response time was the fastest when front leg body roundhouse kicked at 140 bpm of stepping in place tempo. Stepping in place tempo between 140 and 160 bpm is the most effective to optimize the response time. And, More effective response time was front leg roundhouse kick as compared with back leg roundhouse kick and, body roundhouse kick as compared with head roundhouse kick. The findings in this study will provide useful information for performance improvement and will help with strategy for taekwondo competition.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.10
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• pp.1407-1413
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• 2005

An experiment was conducted in order to assess the effect of level of RDP:UDP ratio and level of feeding concentrate on milk yield, milk composition and nutrient utilization in lactating crossbred cattle. Twenty four medium producing (-10 kg/d, 45 to 135 days postpartum) lactating crossbred cows were divided into four groups of six animals each in a 2${\times}$2 factorial completely randomized design. The cows in group 1 were fed concentrate mixture I containing 59:41 RDP:UDP ratio (low UDP) at normal plane (LUDP+NP), in group 2 were fed low UDP ration at 115% of NRC (1989) requirements (LUDP+HP), whereas cows in group 3 were fed concentrate mixture II containing 52:48 RDP:UDP ratio (high UDP) at normal plane (HUDP+NP) and in group 4 were fed high UDP ration at 115% of NRC (1989) requirements (HUDP+HP). Green jowar was fed ad libitum as the sole roughage to all the animals. The experimental feeding trial lasted for 105 days. The total dry matter intake (DMI), DMI/100 kg body weight, DMI/kg $W^{0.75}$, digestibilities of DM, OM, CP, CF, EE and NFE and intakes of TDN and DCP did not differ significantly among the different groups and also due to both UDP level and plane of nutrition and also due to their interaction. The total dry matter intake varied from 145 g in group 1 (LUDP +NP) to 152.57 g/kg $W^{0.75}$ in group 2 (LUDP+HP) diet. However, increase in milk yield with increased UDP level and also with increased plane of nutrition was observed consistently throughout the experimental period. The average milk yield was 7.66, 8.15, 8.64 and 9.35 kg in groups 1, 2, 3 and 4, respectively and there was no significant difference in milk yield among different groups of cows. The overall daily average milk yields in cows fed with low and high UDP diets were 7.91 and 8.99 kg, respectively and at normal and higher plane of feeding the milk yields were 8.15 and 8.75 kg/day, respectively. Thus, there was 13.65% increase in milk yield due to high UDP level and 7.36% due to higher plane of feeding. The daily 4% FCM yields were 9.20 kg for low UDP diet and 10.28 kg for high UDP diet, whereas it was 9.11 kg at normal plane of feeding and 10.37 kg at higher plane of feeding. Fat yields for the corresponding treatment groups were 0.37, 0.43, 0.41 and 0.48 kg, respectively. The 4% FCM yield and also fat yield did not differ significantly among different dietary treatments and also due to UDP level and plane of nutrition, however, 4% FCM yield was increased by 11.74% with high UDP level and 13.83% with higher plane of feeding. The values for total solids, fat, lactose, solids-not-fat and gross energy contents in milk differed significantly (p<0.05) among the different groups and were significantly (p<0.05) higher in milk of cows fed LUDP+HP diet followed by HUDP+HP diet. Total solids (14.65 and 13.83%), lactose (5.44 and 4.92%), solids-not-fat (9.44 and 8.83%) and gross energy (887 and 838 kcal/kg) of milk decreased significantly (p<0.05) with increased UDP level while total solids (13.84 and 14.64), fat (4.84 and 5.36%) and gross energy (832 and 894 kcal/kg) increased significantly (p<0.05) with increase in plane of feeding. Gross and net energetic efficiencies and also gross and net efficiencies of nitrogen utilization for milk production were not significantly different among different groups and also were not affected significantly due to either UDP levels or plane of feeding. Results of the present study suggest that, increasing UDP level from 41% to 48% of CP in concentrate mixture and also increasing plane of feeding from normal (100%) to 115% of NRC requirements maintain a consistently higher milk production.

• The Korean Journal of Emergency Medical Services
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• v.15 no.1
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• pp.47-63
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• 2011

Purpose : This research is to examine the work and job satisfaction of paramedics in the emergency room of university hospitals. This research is done to provide basic data needed for establishing work realms of paramedics in hospitals and to enhance their degree of satisfaction. Methods : Research questionnaire survey was conducted on 141 paramedics working in the emergency room of 32 university hospitals from August 24, 2010 to September 30, 2010 through direct visits and telephone interviews or email to explain the purpose of this research and assurance of confidentiality of responses on the questionnaires. As the tool for the degree of job satisfaction, 'The Index of Work Satisfaction' developed by Slavitt, et al(1978) and revised and supplemented by Soon-shim Kim and Hye-ran Kwon(2002) was used. The collected data were analyzed by evaluating frequency, percentage, mean, standard deviation, t-test and ANOVA, Cronbach's $\alpha$ by using SPSS WIN 18.0 program. Results : 1. Investigating the work and role of paramedics in the emergency room of university hospitals, electrocardiogram(EKG) was found to be highest with $\alpha$ was widely used with the rate of patient evaluation and test area. In the medical treatment for patients area, cardiopulmonary resuscitation(CPR) with 95%(134 persons) and ventilation assistance through ambu bagging(BVM) with 95%(134 persons) were found to be high. $\alpha$ were performed. In the role within the hospital and other areas, a member of CPR team in the hospital accounted for 78%(110 persons). 2. In the measurements of the job satisfaction of paramedics working at university hospitals, the total mean score was 2.91. The mean score in each question area indicated: section on job 3.48, autonomy 3.05, interaction 3.01, organizational demand 2.85, working conditions 2.67, salaries 2.40. This result obviously demonstrates the work of paramedics itself was most satisfied but the salaries were most dissatisfied. 3. In the measurements of the job satisfaction of paramedics working at university hospitals, job satisfaction based on the general characteristics showed significant difference in age (F=6.547, p=.002), gender (F=4.436, p=.000) marital status (F=-3.270, p= .001), religion (F=2.041, p= .043), motive for application (F=3.603, p= .015), and salary (F=6.658, p= .000). 대학병원 응급실 내 1급 응급구조사의 업무와 직무만족도 The Journal of the Korean Society of Emergency Medical Technology Vol. 15 (1) 63 4. In the measurements of the job satisfaction of paramedics working at university hospitals, job satisfaction based on the working environmental characteristics showed significant difference in total number of paramedics (F=3.779, p= .012), form of employment (F=5.601, p= .001), existence or non-existence of intention to change jobs (F=-4.037, p= .000). Conclusion : The work of paramedics in the emergency room of university hospitals consists of lots of treatment processes after specialized diagnosis and performance of professionally subdivided works. However, current legislation does not reflect such circumstances to which paramedics are exposed; thus, it should be considered for further revision and modification. The degree of job satisfaction of paramedics in the emergency room of university hospitals was high but low in salaries and working conditions were the weak points. The measures to enhance their degree of job satisfaction should be taken though improvement of labor conditions such as consideration of the rate of increase in salaries, compensation for overtime work, providing rest areas, improvement of current employment system, and conversion of temporary employees into regular employees.

• The Korean Journal of Nuclear Medicine
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• v.38 no.5
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• pp.338-343
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• 2004

Purpose: The purpose of this study was to develop a small animal PET using dual layer phoswich detector to minimize parallax error that degrades spatial resolution at the outer part of field-of-view (FOV). Materials and Methods: A simulation tool GATE (Geant4 Application for Tomographic Emission) was used to derive optimal parameters of small PET, and PET was developed employing the parameters. Lutetium Oxyorthosilicate (LSO) and Lutetium-Yttrium Aluminate-Perovskite(LuYAP) was used to construct dual layer phoswitch crystal. $8{\times}8$ arrays of LSO and LuYAP pixels, $2mm{\times}2mm{\times}8mm$ in size, were coupled to a 64-channel position sensitive photomultiplier tube. The system consisted of 16 detector modules arranged to one ring configuration (ring inner diameter 10 cm, FOV of 8 cm). The data from phoswich detector modules were fed into an ADC board in the data acquisition and preprocessing PC via sockets, decoder block, FPGA board, and bus board. These were linked to the master PC that stored the events data on hard disk. Results: In a preliminary test of the system, reconstructed images were obtained by using a pair of detectors and sensitivity and spatial resolution were measured. Spatial resolution was 2.3 mm FWHM and sensitivity was 10.9 $cps/{\mu}Ci$ at the center of FOV. Conclusion: The radioactivity distribution patterns were accurately represented in sinograms and images obtained by PET with a pair of detectors. These preliminary results indicate that it is promising to develop a high performance small animal PET.

• Journal of Elementary Mathematics Education in Korea
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• v.5 no.1
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• pp.99-120
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• 2001

The purpose of this thesis is to find the guiding direction of mathematical communication in lower grade students of elementary school and to present a new direction about the effect of using concrete material in communication. It is expected that mathematical communication increases when concrete material is used for the students of the lower grades, who are in concrete operational period. Therefore, this study ai s to investigate what characteristics there are in mathematical communication of second grade students and what effect concrete materials have on mathematical communication and learning. The analysis of the teaching record shows that the second grade students use alternative terms in the process of communication since they are not familiar with mathematical symbols or terms, which is a characteristic of communication in a mathematics class in which concrete material is used. In the process of teaming the students apply their living experiences to their teaming. Since a small number of students lead class, the interaction between students is also led by them. The direction of communication in a small group is not centered around solution of a problem, and most students show a more interest in finding answers than in the process of learning. The effect that concrete material has on communication plays an important role in promoting students' speaking activity; it allows students to identify and correct their errors more easily. It also makes students' activities more predictable, and it increases a small group activities through the medium of concrete material. However, it was also noticed that students' listening activities are not appropriately developed since they do not pay attention to a teacher who uses concrete material. The effects that concrete material has on mathematics class can be summarized as follows. Concrete material promotes students' participation in class by triggering their interest of learning of mathematics and helps them to understand the course of learning. It also helps the teaming and formation of concepts for children of low academic performance. And it makes a phased learning possible according to students' ability to use concrete material and to solve a problem. Based upon the results above mentioned, the use of concrete material is absolutely needed in mathematics classes of lower grade elementary school students since it increases communication and gives much influence on mathematics learning. Therefore, teachers need to develop teaching or learning method which can help increase communication, considering the characteristics of students' communication.