• Sleep Medicine and Psychophysiology
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• v.17 no.2
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• pp.100-108
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• 2010

Objectives: "Internet-addiction" came into common use not only in clinical setting but also in everyday life. But, pathophysiology and diagnostic criteria of the internet addiction remain unknown. Because adolescents are in developing period, they might be vulnerable to the internet addiction, depression and sleep-related problem. The objectives of this study were to investigate the characteristics of internet addiction and its association with sleep pattern and depression in Korean adolescence. Methods: Subjects were 799 middle and high school students in Seoul, Korea. We administered a self-reported questionnaire including socio-demographic data, Korean versions of Young's Internet Addiction Scale (YIAS), Pittsburgh Sleep Quality Index (PS-QI), the Center for Epidemiologic Studies for Depression Scale (CES-D) and questions about internet using patterns. Data of 696 subjects were included in analysis. Chi-square tests were used to analyze proportional differences, and ANOVA with post-hoc tests were used to analyze differences among groups. Partial correlation analyses were performed to analyze the correlation of internet addiction with other variables (two-tailed, p<0.05). Results: Of the 696 participants (grade 2 of middle school; M2 135 vs. grade 1 of high school; H1 238 vs. grade 2 of high school; H2 323), 2.0% (n=14) were internet-addicted (IA), 27.7% (n=193) were over-using (OU) and 70.3% (n=489) were not-addicted (NA). The mean scores of YIAS, PSQI and CES-D scores were 35.24${\pm}$12.78, 5.53${\pm}$3.04 and 16.72${\pm}$8.69, respectively. In higher grade students, average total sleep time was shorter (M2 426.20${\pm}$67.68 min. vs. H1 380.47${\pm}$62.57 min. vs. H2 354.67${\pm}$73.37 min., F=51.909, p<0.001), and PSQI (4.69${\pm}$3.14 vs. 5.42${\pm}$3.15 vs. 5.97${\pm}$2.83, F=8.871, p<0.001) CES-D (13.53${\pm}$8.37 vs. 16.96${\pm}$8.24 vs. 17.87${\pm}$8.84, F=12.373, p<0.001) scores were higher than those of lower grade students. Comparing variables among IA, OU and NA groups, computer using time not for study (96.36${\pm}$63.31 min. vs. 134.92${\pm}$86.79 min. vs. 213.57${\pm}$136.87 min., F=34.287, p<0.001) and portable device using time not for study (84.22${\pm}$79.11 min. vs. 96.97${\pm}$91.89 min. vs. 152.31${\pm}$93.64 min., F= 5.400, p=0.005) were different among groups. PSQI (5.26${\pm}$2.97 vs. 6.08${\pm}$2.97 vs. 7.50${\pm}$4.41, F=8.218, p<0.001) and CES-D scores (15.40${\pm}$8.08 vs. 19.05${\pm}$8.42 vs. 30.43${\pm}$13.69, F=32.692, p<0.001) were also different among groups. YIAS score were correlated with computer using time not for study (r=0.356, p<0.001) and portable device using time not for study (r= 0.136, p<0.001). PSQI score (r=0.237, p<0.001) and CES-D score (r=0.332, p<0.001). YIAS score and PSQI score (r=0.131, p= 0.001), YIAS and CES-D score (r=0.265, p<0.001), PSQI score and CES-D score (r=0.357, p<0.001) were correlated each other. Conclusion: These results suggested that adolescents' internet-addiction was correlated with not only computer and portable device using time not for study but also depression and sleep-related problems. We should pay attention to depression and sleep-related problems, when evaluating internet-addiction in adolescents.

• Journal of Nutrition and Health
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• v.41 no.7
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• pp.621-633
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• 2008

Diabetes mellitus (DM) is a well-established independent risk factor for cerebral infarction (CI). Additionally, the DM as well as CI are influenced significantly by health-related behaviors and diets. The aim of this study was to compare the food habits, nutrient intakes, and dietary patterns and quality in DM patients with CI (DM-CI) and without CI. This study was accomplished with 68 subjects (DM-CI group = 28, DM group = 40). Health-related behaviors, food habits, nutrient intakes and dietary quality were investigated. As a result, the mean ages and durations of diabetes in DM-CI and DM groups were $65.6{\pm}9.2$, $10.9{\pm}8.5$ and $69.2{\pm}3.0$, $9.7{\pm}8.4$ years, respectively. The health-related behaviors such as, smoking, alcohol drinking, and regular exercising in both groups were significantly different (p < 0.05) showing the number of subjects who were smoking and drinking alcohol was significantly higher in DM-CI group and the opposit result was seen for exercise. In male subjects, the intake of carbohydrate and sodium of DM-CI group were significantly higher than those of DM group (p < 0.05). In female subjects, the intake of calorie, carbohydrate, fat, sodium, and cholesterol were significantly higher in the DM-CI group (p < 0.05). Daily intake of vitamin $B_1$, vitamin $B_2$, folate, vitamin C, and calcium were significantly higher in DM group (p < 0.05). In the comparison with the dietary reference intake for Koreans (KDRI), vitamin $B_1$, vitamin $B_2$, folate, and calcium intakes were lower in DM-CI group whereas calcium and zinc intakes were in DM group. Moreover, index of nutritional quality (INQ) of vitamin $B_1$, vitamin $B_2$, vitamin C, folate, and calcium were lower significantly in DM-CI group (p < 0.05). Dietary quality including dietary diversity score (DDS), GMVDF (grain, meat, vegetable, dairy, fruit), and dietary quality index (DQI) was significantly lower in DM-CI group (p < 0.05). According to the results, diabetic mellitus patients accompanied by cerebral infarction had poorer eating patterns and dietary quality in accordance with poorer health-related behaviors compared with the DM patients without CI.

• Korean Journal of Environment and Ecology
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• v.33 no.6
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• pp.664-676
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• 2019

This study aimed to analyze the bioacoustics and habitat environment of the cicadas inhabiting Taebaeksan National Park, an sub-alpine region in Korea. The mating calls of the cicadas were recorded for approximately 3 months, between July and September of 2018. The recording devices were installed in Daedeoksan valley and Baekcheon valley, inside Taebaeksan National Park, and the sounds were recorded 24 hours a day. In order to obtain the habitat distribution data of the cicadas, the sounds were recorded from 111 spots located in the Taebaeksan National Park trail in August 2018. The daily weather data was obtained from the Taebaek city weather center. The results of the study demonstrated that 5 species of cicadas inhabit Taebaeksan National Park, namely, Leptosemia takanonis, Lyristes intermedius, Kosemia yezoensis, Hyalessa fuscata, and Meimuna opalifera. The time of appearance for L. takanonis was early July to mid-July, and that for L. intermedius, K. yezoensis, H. fuscata, and M. opalifera was mid-July to early September. Analysis of the circadian rhythm revealed that L. intermedius, K. yezoensis, and H. fuscata started producing mating calls between 6:00 and 7:00, which ended at around 19:00 for all the three species. The peak time for producing mating calls was 11:00 for L. intermedius, 12:00 for H. fuscata, and around 13:00 to 14:00 for K. yezoensis. The environmental factors influencing the mating calls of the cicadas inhabiting Taebaeksan National Park were analyzed by logistic regression. The results showed that the probability of producing mating calls increased by 1.192 and 1.279 times in L. intermedius and K. yezoensis, respectively, when the average temperature increased by one degree. When the duration of sunlight increased by one hour, the probability of producing mating calls increased by 4.366 and 2.624 times in L. intermedius and H. fuscata, respectively. Analysis of the interspecific effects revealed that when H. fuscata produced a single mating call, the probability of producing mating calls increased by 14.620 and 2.784 times in L. intermedius and K. yezoensis, respectively. When K. yezoensis and L. intermedius produced mating calls, the probability of producing mating calls in H. fuscata increased by 11.301 and 2.474 times, respectively. L. intermedius and K. yezoensis did not have any effects on each other with respect to the production of mating calls. Analysis of the habitat environment of each species revealed that their habitats were located at altitudes of 1,046 m (780~1,315 m) for L. intermedius, 1,072 m (762~1,361 m) for K. yezoensis, and 976 m (686~1,245 m) for H. fuscata. Unlike H. fuscata, which was found at a low altitude, K. yezoensis and L. intermedius were not found at altitudes lower than 700 m. Analysis of the average aspect of the habitats of each of the cicada species revealed that L. intermedius was found at 166° (125~207°), K. yezoensis was found at 100° (72~128°), and H. fuscata was found at 173° (118~228°). Examination of the distribution of each of the cicada species revealed that they were predominantly distributed in the ridges and slopes located in the southeastern region of Munsubong in Taebaeksan. In summary, L. intermedius and K. yezoensis was found to inhabit higher altitudes in Taebacksan National Park than H. fuscata, which was found throughout the Korean peninsula. Additionally, the main aspect of the cicada habitat was found to be the southeastern region (100~173°), which has good access to daylight.

• Journal of Nutrition and Health
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• v.50 no.3
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• pp.270-283
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• 2017

Purpose: This study was conducted to examine coffee consumption behaviors, dietary habits, and nutrient intakes by coffee intake amount among university students. Methods: Questionnaires were distributed to 300 university students randomly selected in Gongju. Dietary survey was administered during two weekdays by the food record method. Results: Subjects were divided into three groups: NCG (non-coffee group), LCG (low coffee group, 1~2 cups/d), and HCG (high coffee group, 3 cups/d) by coffee intake amount and subjects' distribution. Coffee intake frequency was significantly greater in the HCG compared to the LCG (p < 0.001). The HCG was more likely to intake dripped coffee with or without milk and/or sugar than the LCG (p < 0.05). More than 80% of coffee drinkers chose their favorite coffee or accompanying snacks regardless of energy content. More than 75% of coffee takers did not eat accompanying snacks instead of meals, and the HCG ate them more frequently than LCG (p < 0.05). Breakfast skipping rate was high while vegetable and fruit intakes were very low in most subjects. Subjects who drank carbonated drinks, sweet beverages, or alcohol were significantly greater in number in the LCG and HCG than in the NCG (p < 0.01). Energy intakes from coffee were $0.88{\pm}5.62kcal/d$ and $7.07{\pm}16.93kcal/d$ for the LCG and HCG. For total subjects, daily mean dietary energy intake was low at less than 72% of estimated energy requirement. Levels of vitamin C and calcium were lower than the estimated average requirements while that of vitamin D was low (24~34% of adequate intake). There was no difference in nutrient intakes by coffee intake amount, except protein, vitamin A, and niacin. Conclusion: Coffee intake amount did not affect dietary nutrient intakes. Dietary habits were poor,and most nutrient intakes were lower than recommend levels. High intakes of coffee seemed to be related with high consumption of sweet beverages and alcohol. Therefore, it is necessary to improve nutritional intakes and encourage proper water intake habits, including coffee intake, for improved nutritional status of subjects.

• Journal of Nutrition and Health
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• v.48 no.5
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• pp.407-418
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• 2015

Purpose: Given that the indicators related to chronic diseases are important to evaluating goals of the national health policy, the aim of this study was to develop dietary behavior items available in the Korea National Health and Nutrition Examination Survey. Methods: The dietary behavior items were developed based on the literature reviews, need assessment of the field, expert focus-group interviews, and expert advisory meeting. Questions for each dietary behavior item were developed by reflecting on environmental, personal, and behavior factors of the ecological frame and then revised through expert focus-group interview and expert advisory meeting. The understanding and reliability of the developed questionnaire were assessed by cognitive interview and test-retest reliability. Results: The developed items were sodium and salt intake, added and simple sugar intake, enough time to consume a meal for all ages, caffeine drinks and fresh/healthy food intake for children and adolescents, and limited dietary intake, fresh/healthy food intake for seniors. In most questions except some questions on sodium and salt intake, subjects understood over 70% and consistency of responses based on the kappa values was acceptable. Conclusion: Developed dietary behavior items are expected to be useful for evidence-based nutrition policy, interventions and research targeting dietary patterns through investigating and monitoring dietary behavior patterns.

• Journal of Broadcast Engineering
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• v.5 no.2
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• pp.247-259
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• 2000

This paper introduces a new technique that reduces the search times and Improves the accuracy of motion estimation using high temporal and spatial correlation of motion vector. Instead of using the fixed first search Point of previously proposed search algorithms, the proposed method finds more accurate first search point as to compensating searching area using high temporal and spatial correlation of motion vector. Therefore, the main idea of proposed method is to find first search point to improve the performance of motion estimation and reduce the search times. The proposed method utilizes the direction of the same coordinate block of the previous frame compared with a block of the current frame to use temporal correlation and the direction of the adjacent blocks of the current frame to use spatial correlation. Based on these directions, we compute the first search point. We search the motion vector in the middle of computed first search point with two fixed search patterns. Using that idea, an efficient adaptive predicted direction search algorithm (APDSA) for block matching motion estimation is proposed. In the experimental results show that the PSNR values are improved up to the 3.6dB as depend on the Image sequences and advanced about 1.7dB on an average. The results of the comparison show that the performance of the proposed APDSA algorithm is better than those of other fast search algorithms whether the image sequence contains fast or slow motion, and is similar to the performance of the FS (Full Search) algorithm. Simulation results also show that the performance of the APDSA scheme gives better subjective picture quality than the other fast search algorithms and is closer to that of the FS algorithm.

• Journal of Biomedical Engineering Research
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• v.24 no.2
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• pp.133-140
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• 2003

In this study, muscle activity was measured using surface EMG (sEMG) during a voluntary maneuver (ankle dorsiflexion) in the supine position was compared pre and post gait training. Nine patients with incomplete spinal cord injury participated in a supported treadmill ambulation training (STAT), twenty minutes a day, five days a week for three months. Two tests, a gait speed test and a voluntary maneuver test, were made the same day, or at least the same week, pre and post gait training. Ten healthy subjects' data recorded using the same voluntary maneuvers were used for the reference. sEMG measured from ten lower limb muscles was used to observe the two features of amplitude and motor control distribution pattern, named response vector. The result showed that the average gait speed of patients increased significantly (p〈0.1) from 0.47$\pm$0.35 m/s to 0.68$\pm$0.52 m/s. In sEMG analysis, six out of nine patients showed a tendency to increase the right tibialis anterior activity during right ankle dorsiflexion from 109.7$\pm$148.5 $mutextrm{V}$ to 145.9$\pm$180.7 $mutextrm{V}$ but it was not significant (p〈0.055). In addition, only two patients showed increase of correlation coefficient and total muscle activity in the left fide during left dorsiflexion. Patients' muscle activity changes after gait training varied individually and generally depended on their muscle control abilities of the pre-STAT status. Response vector being introduced for quantitative analysis showed good Possibility to anticipate. evaluate, and/or guide patients with SCI, before and after gait training.

• Journal of the Korean earth science society
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• v.33 no.2
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• pp.148-161
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• 2012

The intensive observation (ProbeX-2010) with 6-hour launches of radiosonde was performed over Seoul metropolitan area (Dongducheon, Incheon Airport, and Yangpyeong) from 13 Aug. to 3 Sep. 2010. Five typical heavy rainfall patterns occurred consecutively which are squall line, stationary front, remote tropical cyclone (TC), tropical depression, and typhoon patterns. On 15 Aug. 03 KST, when squall line developed over Seoul metropolitan area, dry mid-level air was drawn over warm and moist low-level air, inducing strong convective instability. From 23 to 26 Aug and from 27 to 29 Aug. Rainfall event occurred influenced by stationary front and remote TC, respectively. During the stationary frontal rainy period, thermal instability was dominant in the beginning stage, but dynamic instability became strong in the latter stage. Especially, heavy rainfall occurred on 25 Aug. when southerly low level jet formed over the Yellow Sea. During the rainy period by the remote TC, thermal and dynamic instability sustained together. Especially, heavy rainfall event occurred on 29 Aug. when the tropical air with high equivalent potential temperature (>345 K) occupied the deep low-middle level. On 27 Aug. and 2 Sep. tropical depression and typhoon Kompasu affected Seoul metropolitan area, respectively. During these events, dynamic instability was very strong.

• Progress in Medical Physics
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• v.14 no.1
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• pp.15-19
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• 2003

High dose rate (HDR) brachytherapy for treating a cervix carcinoma has become popular, because it eliminates many of the problems associated with conventional brachytherapy. In order to improve the clinical effectiveness with HDR brachytherapy, a dose calculation algorithm, optimization procedures, and image registrations need to be verified by comparing the dose distributions from a planning computer and those from a phantom. In this study, the phantom was fabricated in order to verify the absolute doses and the relative dose distributions. The measured doses from the phantom were then compared with the treatment planning system for the dose verification. The phantom needs to be designed such that the dose distributions can be quantitatively evaluated by utilizing the dosimeters with a high spatial resolution. Therefore, the small size of the thermoluminescent dosimeter (TLD) chips with a dimension of <1/8"and film dosimetry with a spatial resolution of <1mm used to measure the radiation dosages in the phantom. The phantom called a pelvic phantom was made from water and the tissue-equivalent acrylic plates. In order to firmly hold the HDR applicators in the water phantom, the applicators were inserted into the grooves of the applicator holder. The dose distributions around the applicators, such as Point A and B, were measured by placing a series of TLD chips (TLD-to-TLD distance: 5mm) in the three TLD holders, and placing three verification films in the orthogonal planes. This study used a Nucletron Plato treatment planning system and a Microselectron Ir-192 source unit. The results showed good agreement between the treatment plan and measurement. The comparisons of the absolute dose showed agreement within $\pm$4.0 % of the dose at point A and B, and the bladder and rectum point. In addition, the relative dose distributions by film dosimetry and those calculated by the planning computer show good agreement. This pelvic phantom could be a useful to verify the dose calculation algorithm and the accuracy of the image localization algorithm in the high dose rate (HDR) planning computer. The dose verification with film dosimetry and TLD as quality assurance (QA) tools are currently being undertaken in the Catholic University, Seoul, Korea.

• Communications of Mathematical Education
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• v.13 no.2
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• pp.563-589
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• 2002

고학년으로 갈수록 지필 환경에만 머무르는 현실 속에서 생활 및 예술 작품 등에서 수학적 원리와 개념을 발견하도록 하는 테셀레이션 수업은 학생들의 흥미와 호기심을 유발하고 수학의 아름다움을 느끼게 하는 것 이상으로 기하학적 사고의 기초를 학습하는데 도움을 줄 수 있다. 이에 본 연구는 4학년까지 적용되고 있는 7차 교육과정을 중심으로 새롭게 등장하고 있는 테셀레이션에 대한 이해 및 교수 학습 자료가 체계적으로 정비되어 있지 못한 현실적인 문제의 해결 방안으로서 테셀레이션을 활용한 수학 학습의 내용을 분석하여 교사들에게는 테셀레이션의 이해 및 교수 학습 자료로서 , 학생들에게는 수학의 기하적 개념들을 쉽고 재미있게 학습할 수 있는 학습도구로서 활용할 수 있도록 하는 것을 목적으로 테셀레이션을 구현할 수 있는 컴퓨터 소프트웨어를 활용하여 테셀레이션 교수 학습 자료를 개발하였고 이를 위해 다음과 같은 연구 내용을 설정하였다. 가. 테셀레이션의 정의와 예 그리고 종류를 알아보고 테셀레이션 속의 수학적 개념을 활용방법과 함께 제시한다. 나. 제7차 초등 수학 교육과정 중 도형 영역과 규칙성과 함수 영역을 중심으로 테셀레이션을 적용할 수 있는 내용영역을 분석하고 컴퓨터 소프트웨어를 활용한 테셀레이션 자료를 제시한다. 다. 제작된 테셀레이션 교수 학습 자료의 효과적 활용을 위한 활용 방안을 탐색한다. 라. 제작된 테셀레이션 교수 학습 자료의 활용 효과를 알아보기 위해 적용 실험을 하고 이에 대한 학생들의 반응을 분석하여 학습의 효과를 밝힌다. 제작된 테셀레이션 교수 학습 자료의 적용 실험을 위하여 광주대성초등학교 6학년 한 반을 선정하였고 약 4주에 걸쳐 컴퓨터 소프트웨어를 활용한 테셀레이션 교수 학습 자료를 투입하여 4번의 활동수업을 실시하였다. 수업 후 작성된 학습지와 소감문 및 연구자에 의해 관찰된 수업내용을 바탕으로 다음과 같은 연구 결과를 얻을 수 있었다. 첫째, 제7차 초등 수학 교육과정 중 도형 영역과 규칙성과 함수 영역을 중심으로 컴퓨터 소프트웨어를 활용한 테셀레이션 자료를 제시한 결과 지필적 환경에서 제한적이었던 탐구하고 조작해보는 활동을 할 수 있는 역동적인 수학 실험실 환경이 제공됨으로써 도구적 이해가 아닌 관계적 이해를 하는 것을 확인할 수 있었다. 수학적 개념을 암기하는 것에서 벗어나 자연스런 조작을 통해 학생들이 개념을 이해하고 탐구하는 과정 속에서 학생들은 수학을 공부한다기 보다는 수학 속에서 재미있게 놀이한다는 생각을 가지고 수업에 참여하였고 배우는 즐거움을 알고 자신감을 가지며 더 나아가 창의적인 생각을 하도록 하는 기회를 줄 수 있었다. 둘째, 테셀레이션은 우리 생활 속에서 쉽게 발견할 수 있는 것으로 수학이 단순히 책에서만 한정되지 않고 다양한 분야 즉 디자인, 생활 속에서의 벽지문양과 포장지, 예술작품 등에 활용되고 있음을 체험함으로써 수학이 실생활에 광범위하게 활용되고 있음을 알게 하였다. 역으로 생활 속에서의 테셀레이션을 통해 수학적 개념을 찾는 과정을 통해 수학이 아름다우면서도 실용적이라는 생각을 심어줄 수 있었다. 셋째, 테셀매니아, GSP, 캐브리, 거북기하 등 평소 수업에서는 활용도가 적은 컴퓨터 소프트웨어를 활용함으로써 컴퓨터 소프트웨어 자체에서 오는 호기심뿐만이 아니라 직접 조작하여 테셀레이션 작품과 개념을 익히고 새로운 작품과 학습을 해 내는 과정을 통해 자신감과 성취감 등에 있어 큰 변화가 있음을 발견할 수 있었다. 컴퓨터 기능이 미숙한 학생의 경우 처음에는 당황해 하고 어려워하는 부분도 있었으나 조작할 시간적 여유를 주고 교사와 우수한 학생들이 도우미로서 역할을 잘해내어 나중에는 큰 어려움 없이 마칠 수 있었다. 테셀레이션이라는 용어가 아직은 생소한 현장에서 교수 학습 자료가 부족하고 그에 따른 이해도 부족한 현실 속에서 컴퓨터 소프트웨어를 활용한 테셀레이션 교수 학습 자료가 교수 학습 현장에 투입되어 유용하게 사용될 수 있는지 그 가능성을 조사한 것을 목적으로 한 본 연구의 결과로서 테셀레이션이라는 주제는 도형 영역과 규칙성과 함수 영역에서 평면 도형의 각과 모양 등의 성질을 탐구하게 하고, 대칭변환의 개념을 효율적으로 학습하게 할 수 있고, 반복되는 모양에서 규칙성을 발견하고 부분과 전체를 파악하여 패턴을 인지할 수 있게 하며 제작하고 분석하는 과정을 통해 여러 가지 수학적 개념과 수학적 창의성, 수학적인 아름다움을 느끼게 할 수 있음을 발견할 수 있었다. 또한 테셀레이션은 수학적 개념은 물론 수학과 미술, 수학과 일상 생활과의 연결성을 논의하고 확인하는 데 흥미로운 주제가 될 수 있다. 초등학교 교육과정에서 새롭게 도입되고 있는 테셀레이션을 활용하여 지도하기 위한 교수 학습 자료로 유용하게 사용될 수 있고 앞으로는 테셀레이션과 관련된 내용이 직접적으로 교육과정 내에서 다루어지고, 또한 테셀레이션을 적용한 수업이 학생들의 기하학적 사고 및 수학적 태도에 미치는 영향과 관련한 연구가 뒤따라야 할 것으로 본다.