• 한국간호교육학회지
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• 제27권1호
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• pp.5-15
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• 2021

Purpose: This study aimed to provide a systematic review and meta-analysis of research on flipped learning effects applied to university students. Methods: The random effect model was applied to 21 papers to calculate the effect size. To verify the moderation effect, a meta regression analysis and meta ANOVA were performed. Publication bias was verified through a funnel plot, and then an Egger's regression test was conducted. Results: The overall average effect size was .69 (95% CI: .51-.87), showing a median effect size, which was statistically significant. The outcome variables were in the order of learning motivation (Hedges' g=.83), self-directed learning (Hedges' g=.78), learning achievement (Hedges' g=.66), and efficacy (Hedges' g=.50), which were statistically significant. Conclusion: Flipped learning was found to be statistically significant in improving self-directed learning, learning motivation, efficacy, and learning achievement amng university students. It is suggestd that this method be actively applied in university education.

• 한국제4기학회지
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• 제17권2호
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• pp.163-163
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• 2003

The study area, Kwangneung Experiment Forest (KEF) is located on the west-central portion of Korean peninsula and belongs to a cool-temperate broadleaved forest zone. At the old-growth deciduous forest near Soribong-peak (533.1m) in KEF, we have established a permanent plot and a flux tower, and the site was registered as a KLTER site and also a KoFlux site. In this study, we aimed to present basic ecological characteristics and synthetic data of carbon budgets and flows, and some monitoring data which are essential for providing important parameters and validation data for the forest dynamics models or biogeochemical dynamics models to predict or interpolate spatially the changes in forest ecosystem structure and function. We made a stemmap of trees in 1 ha plot and analyzed forest stand structure and physical and chemical soil characteristics, and estimated carbon budgets by forest components (tree biomass, soils, litter and so on). Dominant tree species were Quercus serrata and Carpinus laxiflora, and accompanied by Q. aliena, Carpinus cordata, and so on. As a result of a field survey of the plot, density of the trees larger than 2cm in DBH was 1,473 trees per ha, total biomass 261.2 tons/ha, and basal area 28.0 m2/ha. Parent rock type is granite gneiss. Soil type is brown forest soil (alfisols in USDA system), and the depth is from 38 to 66cm. Soil texture is loam or sandy loam, and its pH was from 4.2 to 5.0 in the surface layer, and from 4.8 to 5.2 in the subsurface layer. Seasonal changes in LAI were measured by hemispherical photography at the l.2m height, and the maximum was 3.65. And the spatial distributions of volumetric soil moisture contents and LAIs of the plot were measured. Litterfall was collected in circular littertraps (collecting area： 0.25m2) and mass loss rates and nutrient release patterns in decomposing litter were estimated using the litterbag technique employing 30cm30cm nylon bags with l.5mm mesh size. Total annual litterfall was 5,627 kg/ha/year and leaf litter accounted for 61% of the litterfall. The leaf litter quantity was highest in Quercus serrata, followed by Carpinus laxiflora and C. cordata, etc. Mass loss from decomposing leaf litter was more rapid in C. laxiflora and C. cordata than in Q. serrata litter. About 77% of C. laxiflora and 84% of C. cordata litter disappeared, while about 48% in Q. serrata litter lost over two years. The carbon pool in living tree biomass including below ground biomass was 136 tons C/ha, and 5.6 tons C/ha is stored in the litter layer, and about 92.0 tons C/ha in the soil to the 30cm in depth. Totally more than about 233.6 tons C/ha was stored in DK site. And then we have drawn a schematic diagram of carbon budgets and flows in each compartment of the KEF site.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.338-338
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• 2017

One of the problems in increasing rice production is getting lines or varieties that have high adaptability so that able to produce maximum production in a variety of environmental conditions. One strategy that can be done to get adaptive varieties is through the improvement of native varieties. This research was conducted in rain fed paddy field, Aceh province, Indonesia from June to September 2014. The texture of the soil was clay-loam with the soil pH ranged from 6.5-6.7. Five potential progenies of rice from crossing between native Indonesian rice with introduced rice varieties consist of C3, C4, S3, S5, S6 were used in this study. Besides that, one national rice variety Ciherang also used as a comparison. The plants were growth in the plot with the size of $2m{\times}1.4m$ with plant distance was $20cm{\times}20cm$. The fertilizers used in this study were Urea, NPK, and KCl. Randomized block design with 6 rice progenies/variety and 3 replications were used in this study. There were 18 experimental units and each experimental unit had 10 samples for the sources of data. The variables that were observed in this study including plant height at harvesting time, number of productive tiller, the percentage of empty grains and filled grain per panicle, weight of filled grains per hill, weight of filled grain per plot and yield potential per hectare. Analyzed were also conducted for the depth of root penetration, dry-root weight, dry-shoot weight, shoot-root weight ratio and its correlation with the weight of filled grain per hill. The research results show that there was significant difference on plant height at harvesting time, number of productive tillers, the percentage of empty grains and filled grain per panicle, weight of filled grains per hill, weight of filled grain per plot and yield potential per ha (p>0.01) among the treatments. In addition, depth root penetration, dry-root weight, dry-shoot weight, shoot-root weight ratio also had significant difference (p>0.01) among the treatment. The highest plant at harvesting time was found in S6, reaching 129.8 cm and the shortest plants was found in C3 reaching 107.5 cm. The largest number of productive tillers and the highest percentage of filled grains per panicle were found in Ciherang reaching 10.5 tillers and 80.7% respectively. Ciherang also had the heaviest weight of filled grains per hill and per plot reaching 21.1 g and 2.18 kg respectively. Whereas, S6 had the lowest number of tillers and the lowest percentage of filled grain per panicle.. The highest yield potential per ha was found in Ciherang reaching 7.79 tons. Among the progenies, S5 had the highest yield potential reaching 5 tons/Ha. The result also showed significant relationship between shoot-root weight ratio with weight of filled grains per hill. The highest value of shoot-root weight ratio (1.57) in Ciherang is thought had closed relationship with its yield potential.

• 한국환경복원기술학회지
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• 제10권2호
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• pp.84-96
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• 2007

The purpose of this study was to select herbaceous plants that can be used for presenting various views and biodiversity on the extensive rooftop greening. Experiment plots were constructed in July 2005 on the rooftop of the Administration Building in the Seoul Women's University. For this experiment, planters were used to design rooftop greening. The size of a planter is 500mm${\times}$500mm${\times}$100mm and each planter has the water storage plate in the lower part of it. The soil was constructed by mixing pearlite, vermiculite, cocopeat, and leaf mold in the ratio of 6 : 2 : 1 : 1. The plot was divided into the watered plot and the dry plot. Since each plot was constructed 2 times, finally 4 planters were constructed in total. One hundred species were used for the experiment and 9 plants per species were planted in each planter. Plants were organized according to types of plants and the experiment used 86 native herbaceous plants, 6 herbs, and 8 foreign plants. The plots were monitored once a month, from July to November 2005. The length and width of plants were tape-measured and covering rate was calculated by CAD program. "SPSS 10.1" was used for a statistical analysis. The result showed no significant difference between the watered plots and the dry plots. In cases of some plants, there were statistically significant differences between the watered planter and dry planter such as follows : Astilbe chinensis and Polygonatum odoratum which are shade plants were measured as the highest value on the watered pots, and Aquilegia buergeriana, Chrysanthemum zawadskii, Calendula arvensis and Gypsophila cerastioides D.Don which are sunny plants were measured as the highest value on the dry plots. According to the final analysis of the data collected and observed for growth condition during the first year of the research, 51 species including Prunella vulgaris var. lilacina and Veronica linaiaefolia in native herbaceous plant, 5 species with Lavandula angustifolia in herbs, and 3 species with Lantana camara and Muscari armeniacum in foreign plants showed the highest growth condition. In conclusion, it is suggested that various plants including sedums could be effectively used for extensive rooftop greening to improve landscape(a view) of the rooftop and increase ecological values.

• 한국전기전자재료학회논문지
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• 제37권3호
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• pp.292-296
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• 2024

In this study, Iron (III) oxide-hydroxide (δ-FeOOH) was successfully synthesized using hydrogen peroxide (H₂O₂) as an oxidizing agent. The synthesis of δ-FeOOH was carried out by controlling the amount of H₂O₂, and pure δ-FeOOH was successfully synthesized in ranges from 0.2 mL to 0.6 mL of H₂O₂. The size of the synthesized δ-FeOOH particles was compared by controlling the amount of oxidant H₂O₂. The average particle size of the synthesized pure δ-FeOOH particles increased from 875.1 nm to 897.2 nm as the amount of H₂O₂ was increased. The optical properties of δ-FeOOH synthesized under these specific conditions were investigated. All δ-FeOOH showed a similar trend of increasing and decreasing light absorption from 800 nm to 400 nm, although there was a slight difference in the amount of light absorption, with the largest amount of light absorption at 410 nm. The band gap energy of δ-FeOOH through the Tauc plot method was about 2.1~2.2 eV when H₂O₂ was 0.2~1.4mL. With a sufficient small particle size, simple control of that particle size, and a small band gap energy enough to absorb light in the visible spectrum, δ-FeOOH could be useful in a variety of applications, including photoelectrochemistry and battery electrodes.

• 한국초지조사료학회지
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• 제23권1호
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• pp.43-48
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• 2003

질소 시용에 의한 치커리의 질산염 축적과 희토처리가 질산염 강하에 미치는 영향을 검토하기 위하여 질소 시비수준에 따른 치커리 잎의 성장과 수량, 엽록소 함량, 질산엽 함량 등을 조사하였으며, 희토처리가 치커리의 생육촉진과 질산태질소 함량 감소에 미치는 영향 등을 조사한 결과를 요약하면 다음과 같다. 1. 질소 시비수준이 증가할수록 치커리 잎이 두꺼워지고 잎 크기도 커졌으며, 같은 수준의 질소 시비구에서 희토처리로 잎이 두꺼워지고 잎의 크기도 커졌다. N+2구에서 희토처리 효과가 가장 뚜렷하였다(p<0.05). 2. 질소처리 수준이 높아질수록 치커리 엽중 총 엽록소 함량과 엽록소-a 함량은 감소되었으나 엽록소-b에 대한 엽록소-a의 비율은 증가되었다. 희토처리로 총 엽록소 함량, 엽록소-a 함량 및 엽록소 a/b율이 모두 증가되었으나 통계적인 유의성은 인정되지 않았다. 3. 생체와 건물수량이 질소 시비수준 증가에 따라 증가하였으며, N+2구에서 유의성이 인정되었다(p<0.05). 희토 사용으로 생체수량은 6.7∼17.0%, 건물수량은 9.0∼10.8%증가되었다. 질소 시용증가로 건물율이 감소되었으나 희토시용은 건물율을 4.6∼5.8% 증가시켰다. 4. 질소 시용수준이 높을수록 치커리의 질산 태 질소 함량이 증가하였으나, 희토 엽면살포로 그 함량이 감소되었으며 N+2 처리구에서는 45.9%나 감소되었다. 5. 희토시용은 식물 생장에 필수적 요인인 엽록소 함량을 증가시켜 식물 생장을 촉진하고, 특히 식물체내 질산태질소 강하효과가 뚜렷하여 안전 농산물생산의 가능성을 보여 주었다.

• 한국산학기술학회논문지
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• 제17권11호
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• pp.271-284
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• 2016

본 연구는 임부의 산전우울에 대한 인지행동치료 중재의 효과를 검증하기 위해 수행된 체계적 문헌고찰 및 메타분석 연구이다. 데이터베이스는 CINAHL, PubMed, EMBASE 및 Koreamed, 국회도서관, 한국학술정보(Korean studies Information Service System, KISS), 한국의학논문데이터베이스 등 국내외 domain을 활용하였다. 검색은 ((Perinatal OR Antenatal OR Antepartum OR Pregnant) AND Depression) AND Women AND (CBT OR (Cognitive behavioral AND (Therapy OR Treatment)))와 '산전우울', '임부', '인지행동치료' 등의 검색어로 2016년 5월까지 출판된 문헌을 검토하였다. 분석은 R을 이용한 임의효과모형을 적용하여 산전우울과 불안의 효과크기를 각각 산출하였으며, 효과크기의 이질성을 검증하기위해 메타 ANOVA를 활용하여 조절효과분석을 실시하였다. 그리고 funnel plot, Egger's regression test, fail-safe N, trim-and-fill 분석을 활용한 출간오류분석과 민감성 분석을 실시하여 전체 연구 결과의 타당성을 검증하였다. 연구결과 총 180편의 문헌이 검색되었으며, 선택배제기준에 따라 최종적으로는 clinical trials 16편을 분석하였다. 분석에 포함된 개별문헌은 Scottish Intercollegiate Guideline Network (SIGN)의 checklist를 통해 비뚤림 위험을 평가하였으며, 대체로 비뚤림 위험은 낮았다. 연구결과 본 연구에서 중재의 산전우울에 대한 효과크기는 Hedges' g=-0.55(95% CI: -0.76~-0.33)로 통계적으로 유의하게 낮았으며, 불안에 대한 효과크기는 Hedges' g=-0.20(95% CI: -0.48~-0.08)이었으나, 통계적으로 유의한 차이는 없었다. 문헌의 이질성, 출판오류의 위험성 등은 낮았다. 본 메타분석결과에 의하면 인지행동치료는 임신부의 산전우울 증세 완화에 보통 정도의 효과가 있음이 밝혀졌다.

• 한국노년학
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• 제37권2호
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• pp.431-444
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• 2017

본 연구는 국내 노인의 인지기능 향상 프로그램의 효과를 확인하기 위해 수행되었다. 2000년부터 2016년까지 4개의 데이터베이스에서 9,624개의 논문을 검색하였고, 최종 14개의 논문이 메타분석을 위해서 선정되었다. 선정된 연구의 질 검증을 위해서 Scottish Intercollegiate Guidelines Network의 controlled trial checklist를 사용하였다. R 프로그램 version 3.3.2(2016-10-31)를 사용하여 효과크기와 이질성 검증, 출간오류를 분석하였다. 인지기능 향상 프로그램의 전체 효과크기는 중간 효과크기를 나타냈고 이질성은 중간 정도의 이질성을 나타냈다(SMD=0.759, 95% CI: 0.506~1.013, $I^2=34%$). 전체 논문의 이질성 검증을 위한 조절효과분석을 실시한 결과 중재종류에 따라 통계적으로 유의한 차이를 보였으며 복합운동중재가 가장 큰 효과크기를 나타냈다(SMD=1.231, 95% CI: 0.658~1.804, $I^2=40.8%$). 출간오류는 Funnel plot과 Egger's regression test를 통해서 통계적으로 유의한 오류가 발견되었지만 오류의 심각정도를 확인하기 위해 Trim-and-Fill 분석을 실시한 결과 전체연구 결과를 번복할 정도의 심각한 오류는 확인되지 않았다. 따라서 노인을 대상으로 한 인지기능 향상 프로그램 중 복합운동중재는 노인의 인지기능 향상에 도움이 될 것으로 사료된다.

• 한국토양비료학회지
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• 제40권4호
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• pp.326-329
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• 2007

Quantifying soil organic carbon (SOC) has long been considered to improve our understanding of soil productivity, soil carbon dynamics, and soil quality. And also SOC could contribute as a major soil management factor for prescribing fertilizers and controlling of soil erosion and runoff. Reducing tillage intensity has been recommended to sequester SOC into soil. On the other hand, determination of traditional SOC could barely identify the tillage practices effect. Physical soil fractionation has been reported to improve interpretation of soil tillage practices impact on SOC dynamics. However, most of these researches were focused onupland soils and few researches were conducted on paddy soils. Therefore, the objective of this research was to evaluate paddy soil tillage impact on SOC by physical soil fractionation. Soils were sampled in conventional-tillage (CT), partial-tillage (PT), no-tillage (NT), and shallow-tillage (ST)plots at the National Institute of Crop Science research farm. Samples were obtained at the three sampling depth with 7.5-cm increment from the surface and were sieved with 0.25- and 0.053-mm screen. Soil organic carbon was determined by wet combustion method. Significant difference of SOC contentwas found among sampling soil depth and soil particle size. SOC content tended to increase at the ST plot with increasing size of soil particle fraction. We conclude that quantifying soil organic carbon by physical soil particle fractionation could improve understanding of SOC dynamics by soil tillage practices.

• Journal of Power Electronics
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• 제16권3호
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• pp.849-860
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• 2016

The high-switching-frequency operation of power converters can achieve high power density through size reduction of passive components, such as capacitors, inductors, and transformers. However, a small-output capacitor that has small capacitance and low effective series resistance changes the small-signal model of the converter power stage. Such a capacitor can make the converter unstable by increasing the crossover frequency in the transfer function of the small-signal model. In this paper, the design and implementation of a high-frequency LLC resonant converter are presented to verify the power density enhancement achieved by decreasing the size of passive components. The effect of small output capacitance is analyzed for stability by using a proper small-signal model of the LLC resonant converter. Finally, proper design methods of a feedback compensator are proposed to obtain a sufficient phase margin in the Bode plot of the loop gain of the converter for stable operation at 500 kHz switching frequency. A theoretical approach using MATLAB, a simulation approach using PSIM, and experimental results are presented to show the validity of the proposed analysis and design methods with 100 and 500 kHz prototype converters.