• 한국환경농학회지
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• 제40권2호
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• pp.73-82
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• 2021

BACKGROUND: The successful management of jujube trees depends on maintaining a balance between reproductive and vegetative growth. In general, heading cuts of trunk stimulate rather vegetative growth, but could decrease flower initiation. This study was conducted to establish a heading-back pruning severities at planting in the one year old 'Daeneung' jujube whip nursery tree by investigating vegetative growth and fruit yield. METHODS AND RESULTS: The heading back pruning severity was assigned as 5 different ranges as follow: one bud (TR-10, heading back pruning was 10 cm above the ground), three buds (TR-30), five buds (TR-50), seven buds (TR-70), and nine buds (TR-90) were left of scion. The number of buds on whip trunk was correlated to the central leader length and increment of trunk cross-sectional area, negatively, and to the tree height and canopy volume, positively. The yields in the TR-50 treatment were higher about 2 times than other treatments. The fruit diameter was not significantly different among the treatments. CONCLUSION: These results indicated that the optimum location of heading-back pruning in one year old 'Daeneung' jujube tree was 50 cm above the ground as evaluated by the balance of reproductive and vegetative growth.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2017년도 9th Asian Crop Science Association conference
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• pp.183-183
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• 2017

In the early part of rice growth, root volume primarily limits the amount of plant-accessible nitrogen (N). Therefore, knowledge of the root development is important for modeling N uptake of rice. The timing when the volume of rhizosphere cover the whole soil is also important to carry out timely top dressing. However, information about initial root expansion and associated N uptake is limited due to intrinsic technical difficulties in assessing below-ground processes. Some studies, however, showed a close relationship between below-ground root and above-ground leaf development, suggesting a possibility that above-ground attributes could serve as surrogates for the root processes. In this study, we investigated the relationship between below-ground and above-ground development of rice. Field experiments were conducted where we cultivated Koshihikari (a leading cultivar in Japan) for four different cropping schedules in 2012. In 2016, Gimbozu (HEG4) and three flowering time mutant lines of Gimbozu (X61 (se13), HS276 (ef7), DMG9 (se13, ef7)) were examined for a single season. Experiments were performed with three replications in a completely randomized design. We monitored ammonium-N concentration ([NH4+-N]) in soil solution by repeatedly taking samples from a porous tubing (10-cm long) vertically inserted at the most distant point from surrounding rice hills. Samples were taken in triplicate (= triplicate tubes) and every three days from transplanting in each experimental unit. For above-ground attributes, leaf area index (LAI) was measured in 2012, whereas soil coverage ratio was estimated by image processing in 2016. Results showed that [NH4+-N] increased gradually after transplanting and then rapidly decreased from a certain day. This distinct drop in [NH4+-N] informed us the timing at which the rice root system reached the point of porous tubing and thus essentially covered the whole soil volume. The LAI at the dropping point was about 0.43 regardless of the cropping schedules in 2012 experiment. In 2016, the coverage ratio at the N dropping point was within the range of 0.12 to 0.19 for four genotypes having different growth durations. In addition, the coverage ratios at seven weeks after the transplanting showed a good correspondence to LAI across the four genotypes. We therefore conclude that both LAI and coverage ratio may serve as robust indicators for root development and might be useful to estimate the timing when the root system fully cover the soil volume. Results obtained here will also contribute to develop models that can predict not only above-ground canopy development but also associated below-ground processes.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2006년도 Proceedings of ISRS 2006 PORSEC Volume I
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• pp.512-515
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• 2006

Forest stand height and volume are important indicators for management purpose as well as for the environmental analysis. Shuttle Radar Topography Mission (SRTM) is backscattered over forest canopy and DSM can be acquired from such scattering characteristic, while National Elevation Dataset (NED) provides bare earth elevation data. The difference between SRTM and NED is estimated as tree height, and it is correlated with forest parameters, it is correlated with forest parameters, including average DBH, Trees per acre, net BF per acre, and total Net MBF. Especially, among them, net Board Foot(BF) per acre is the index that well represents forest volume. The Project site was Douglas-fir dominating plantation area in the western Washington an the northern Oregon in the U.S. This study shows a relationship of high correlation between the forest parameters and the product from SRTM, NED, and ETM+. This research performs multi regression analysis and regression tree algorithm, and can get more improved relationship between several parameters.

• 대한원격탐사학회지
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• 제22권5호
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• pp.427-431
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• 2006

Forest stand height and volume are important indicators for management purpose as well as for the environmental analysis. Shuttle Radar Topography Mission (SRTM) is backscattered over forest canopy and DSM can be acquired from such scattering characteristic, while National Elevation Dataset (NED) provides bare earth elevation data. The difference between SRTM and NED is estimated as tree height, and it is correlated with forest parameters, it is correlated with forest parameters, including average DBH, Trees per acre, net BF per acre, and total Net MBF. Especially, among them, net Board Foot(BF) per acre is the index that well represents forest volume. The Project site was Douglas-fir dominating plantation area in the western Washington an the northern Oregon in the U.S. This study shows a relationship of high correlation between the forest parameters and the product from SRTM, NED, and ETM+. This research performs multi regression analysis and regression tree algorithm, and can get more improved relationship between several parameters.

• Journal of Biosystems Engineering
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• 제26권5호
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• pp.431-440
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• 2001

Generated agri-chemical droplets by orchard sprayers are evaporated regenerated and transported along wind streams. The droplets are deposited to targets after changing their sizes, affecting the retention of droplets. An orchard sprayer, designed for spraying grapevines was studied on the spatial distribution of droplet size. The experimental variables were spray direction (0, 22.5, 45, 67.5 and 90˚), distance(2.5, 3.0 and 3.5 m) and fan speed (2,075 and 3,031 rpm). Droplet sizes were converted and analyzed from spray stains, sampled using water sensitive papers. The number median diameter (NMD) increased with an increase of the distance due to disappeared fine droplets (<50 ㎛): however, the volume median diameter (VMD) decreased due to shrunken large droplets (>100 ㎛). Fast fan speed delivered large droplets to 3.5 m, but the spatial distributions of NMD and VMD were not uniform. Slower fan speed decreased the possibility of evaporation and drift; therefore, plenty of droplets were maintained up to 3.0 m. The upward blasting distance was limited within 3 m, but the limit to the ground level was extended to 3.5 m. Concentrated wind and droplets to the ground level should be redistributed to upper canopy direction, leading more uniform deposits. High speed wind and system pressure should be avoided because of generating fine droplets, which would be disappeared and drifted away.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.332-335
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• 2008

Newly developing SAR (Synthetic Aperture Radar) sensors commonly include high resolution X-band those data are expected to contribute various applications. Recent few studies are presenting potential of X-band SAR data in forest related application. This study tried to investigate the relationship between forest stand parameters and multi-band SAR normalized backscattering. Multi-band SAR data was radiometric corrected to compare signal from different forest stand condition. Then correlation coefficients were estimated between attribute of forest stand map and normalized backscattering coefficients. Although overall correlation coefficients are not high, only X-band shows strong relationship with DBH class than other bands. The signal of C- and L-band is composed of a large number of discrete tree components such as leaves, stems, even background soil. In forest, strength of radar backscattering is affected by complex parameters. Further study might be considered more various forest stand parameters such as canopy density, stand height, volume, and biomass.

• 원예과학기술지
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• 제33권2호
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• pp.155-165
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• 2015

우량 측지묘(측지수 : 10개 이상)를 $3.0{\times}1.0m$ 거리로 심고 수고를 2.5m 정도로 한 세장방추형과 수고를 3.5m로 높인 키큰방추형으로 키우면서 8년간 수체생장, 생산성 및 과실품질을 비교하였다. 재식 4년차에 키큰방추형의 수관용적이 세장방추형보다 커지기 시작하여 5년차에는 주당 수관용적이 키큰방추형은 세장방추형에 비해 25% 정도 더 컸다. 8년 동안의 10a당 누적수량은 키큰방추형이 세장방추형에 비해 14% 정도 증수되었다. 더군다나 재식 5년차 이후로 두 시험구 모두 해거리 및 갈색무늬병이 발생하여, 수세가 종종 불안정하였는데, 키큰방추형의 생산량 감소 및 수세 불안정 정도는 세장방추형보다 덜하였다. 가용성고형물 함량과 착색은 재식 5년차에 키큰방추형이 세장방추형보다 증가하였는데, 이는 키큰방추형의 측지 및 착과가 세장방추형보다 균일하게 배치되면서 수관 내 광투과율이 증가되었기 때문으로 생각되었다. 결론적으로 국내에서 '후지'/M.9 사과나무를 333주/10a 이상으로 재식할 경우 세장방추형의 수고를 3.5m로 높이는 것이 광투과율, 생산량 및 과실품질 측면에서 관행의 세장방추형보다 나을 것으로 판단되었다.

• 한국환경생태학회지
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• 제25권5호
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• pp.639-648
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• 2011

야생동물 이동을 위해 설치된 '생태통로'를 야생조류가 선택적으로 이용하는지 알아보기 위하여 서울시 호암1터널, 까치산근린공원, 덕릉고개 등 육교형 생태통로에서 '생태통로'와 '주변도로'를 이동하는 야생조류를 2006년 6월부터 9월까지 총 9회에 걸쳐 조사하였다. 3개 지역 중 까치산 근린공원, 덕릉고개 등 능선에 위치한 생태통로에서 야생조류는 생태통로를 선택적으로 이용하지 않았으나, 사면에 위치한 호암1터널에서 야생조류는 생태통로를 유의하게 높게 이용하였다. 생태통로의 폭이 90m 이상이거나 사면에 위치할 경우, 야생조류의 이동에 유리한 것으로 판단된다. 생태통로를 이용한 야생조류의 종 구성 측면에서, 관목층 둥지 조류는 2m 이하의 관목층 엽층량과 상관성이 있었고, 수관층 둥지 조류는 7~8m 엽층량과 상관성이 높았다. 야생조류 이동을 위한 생태통로는 대상지 입지 여건에 따라 목표종을 선정해야 하지만, 서울시의 경우 붉은머리오목눈이 등 관목층 조류를 대상종으로 선정하고, 다양한 야생조류의 이동을 위해서는 사면지역에 약 1ha 크기(폭 90m 이상) 생태통로에 2m 이하의 관목층과 8m 이상의 수관층 피도량을 높여주는 산림환경구조를 조성해주는 것이 바람직한 것으로 판단된다.

• 한국태양에너지학회 논문집
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• 제29권5호
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• pp.35-44
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• 2009

In this study, boiling heat transfer coefficients(HTCs) and critical heat flux(CHF) are measured on a smooth square flat copper heater in a pool of pure water with and without carbon nano tubes(CNTs) dispersed at $60^{\circ}C$. Tested aqueous nanofluids are prepared using multi-walled CNTs whose volume concentrations are 0.0001, 0.001, 0.01, and 0.05%. For dispersion of CNTs, polyvinyl pyrrolidone(PVP) is used in distilled water. Pool boiling HTCs are taken from $10kW/m^2$ to critical heat flux for all nanofluids. Test results show that the pool boiling HTCs of the nanofluids are lower than those of pure water in entire nucleate boiling regime. On the other hand, critical heat flux is enhanced greatly showing up to 200% increase at volume concentration of 0.001% CNTs as compared to that of pure water. This is related to the change of surface characteristics by the deposition of CNTs. This deposition makes a thin CNT layer on the surface and the active nucleation sites of heat transfer surface are decreased due to this layer. The thin layer acts as the thermal resistance and also decreases the bubble generation rate resulting in a decrease in pool boiling HTCs. The same layer, however, maintains the nucleate boiling even at very high heat fluxes and reduces the formation of large vapor canopy at near CHF resulting in a significant increase in CHF.

• 한국음향학회지
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• 제40권6호
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• pp.626-648
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• 2021

국내에서는 다양한 공연장르를 운영할 수 있는 다목적 공연장의 수요와 그에 따른 공급이 지속적으로 증가해오고 있다. 그러나 음향적인 측면에서는 다목적 활용에 대응하는 실질적인 고려가 이루어지지 않고 있으며, 많은 시행 착오를 거듭하고 있다. 본 논문에서는 다양한 장르의 공연이 한 공간에서 이루어질 수 있도록 실의 음향특성을 변경하는 방법들을 문헌고찰을 통해 살펴보았다. 실의 음향특성을 용도에 맞게 변화시키는 것을 가변음향이라고 하며, 수동 및 능동제어방식으로 구분된다. 수동제어방식은 가변흡음, 용적가변, 부가잔향실법, 그리고 캐노피 반사 등의 방식으로 구분되는 건축적인 가변방식이며, 능동제어방식은 In-line, Regenerative 그리고 Hybrid 시스템으로 전기적인 방법에 의해 제어된다. 본 연구에서는 각각의 수동제어방식들이 실제 다목적 공연장 및 다양한 장르에 적용된 사례와 그 장단점을 살펴보았다. 또한 각각의 능동제어방식이 적용된 시스템들을 살펴보고, 실제 다목적 공연장에 적용된 사례와 그에 따른 음향적 변화에 대해 알아보았다. 마지막으로 가변음향시스템을 활용한 다목적 홀의 기획 및 설계 단계에서 고려사항을 제안하였다.