• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.234-234
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• 2022

도로에서의 우수를 원활하게 처리하기 위해서 빗물받이 및 연결관 등의 노면 배수시설이 설치되고 있으며, 노면 배수는 측구부를 통해 흘러 빗물받이 유입부로 차집되고 연결관을 통해 하수관거로 배수된다. 그러나 최근 국내 기상패턴의 변화로 국지성 집중호우와 같이 시간당 강우량 증가로 도로부와 저지대에서 배수시설의 배수불량에 따른 도심지 내수침수 피해가 발생하고 있다. 이에 정부에서는 다양한 우수관거 개선사업, 빗물펌프장, 지하저류조와 같은 방재시설을 설치하고 있으나 우수유출저감시설은 대규모 예산이 소요되고 실제 침수지역에 피해 저감효과에 대한 효용성 문제에 대한 제기뿐만 아니라 과밀화된 도심지에서는 지하공간 활용에 한계가 있는 실정이므로 도심지의 다양한 공간을 활용한 도시 배수 및 저류시설에 대한 연구가 필요하다. 따라서 본 연구에서는 유휴 공간인 도로 측구부 공간을 활용하여 도로 노면수를 저류 및 지체할 수 있는 노면수 측구 저류시설의 개념을 제시하고 측구저류조의 활용성을 판단하기 위하여 빗물받이 유입구, 빗물받이, 측구 저류조 및 빗물받이와 측구저류조 연결부에서의 노면수 유입, 유출 및 저류 등의 다양한 흐름 변화를 확인하기 위하여 Fluent 모형의 적용성을 분석하였다. 수치모의 전체 형상은 50x50cm 크기의 빗물받이를 기준으로 양쪽에 2m 길이의 측구 저류조를 원형관으로 연결하여 1/5 축소모형으로 구성하고 격자는 빗물받이 유입부, 빗물받이 및 측구 저류조 내부의 복잡한 3차원 흐름을 모의하기 위해 사면체와 육면체로 조밀하게 생성하였다. 다상유동해석을 위해 VOF(Volume of Fluid)방법을 적용하였고, 수치해석 방법으로는 비정상류, 난류 모형으로는 SST k-ω모형을 적용하였다. 수치모의 조건으로는 설계빈도별(5~30년) 우수유출량을 산정하여 유입 유량별 기존 빗물받이 유입부에서의 유입흐름, 빗물받이 내부에서의 와 발생흐름, 측구 저류조 및 연결관에서의 흐름을 구현하여 분석하였다. 수치모의 결과 빗물받이 유입부에서 연결관을 통한 측구 저류조로 유입되는 유입흐름과 빗물받이 하단부의 배수관을 통해 유출되는 흐름을 정상적으로 구현하였으며, 빗물받이 유입부 및 측구 저류조 연결관에서의 유속변화도 확인할 수 있었다. 또한 빗물받이와 측구 저류조에서 다양한 흐름을 구현하기 위한 Flunet 모형의 적용성을 검토하였으며, 향후 수리실험을 통하여 실제 흐름과의 매개변수 최적화 및 다양한 도로 조건의 변화를 고려한 수치모의 분석을 통하여 지속적인 모형의 검증이 가능할 것으로 판단된다.

• Economic Analysis
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• v.25 no.1
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• pp.34-65
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• 2019

This paper investigates the effects on Korean exports of demand in developed economies, and how these effects have changed since the global financial crisis. As a measure of import demand, we use import intensity-adjusted demand to take into account heterogenous import intensities across components of aggregate demand. Our estimation of a dynamic panel regression model reveals that Korea's exports to the G7 countries were elastic with respect to the import demand of these countries until the global financial crisis, but have shifted to become inelastic since. Furthermore, we separately estimate the effects of the different components of the G7 countries' aggregate demand (private consumption, public consumption, investment and exports). The results show that the decrease in private consumption in the G7 countries during the crisis had a significant impact in causing the decline in Korea's exports to them, but that the increase in their public consumption since the crisis has had a significant effect on driving increased Korean exports to them. The effects of the G7 countries' exports on Korea's exports to them remain positive and significant during both the pre- and post-crisis periods. The effects of the G7 countries' investments on Korea's exports are also positive and significant, but the positive effect has weakened since the crisis. Our findings suggest that the overall effect of changes in the G7 countries' import demand on Korea's exports to them has weakened compared to the pre-crisis period.

• Journal of Marine Life Science
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• v.8 no.2
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• pp.128-135
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• 2023

The present study was tried to identify whether the eel's larva was close to a conger (Conger myriaster), a pipe conger (Muraenesox cinereus) or four species of Anguilla. Experimental fishes were collected by set net in the gulf of enggang, Namhae, Korea from May to June. Their morphological characteristics were compared with adult fishes of a conger, a pipe conger and four species of Anguilla. For genetic classification, DNA was isolated and amplified by using 12S rRNA and 16S rRNA primer set. The PCR products were direct sequencing in both directions. The nucleotide sequences were analyzed using softwares. As results of morphological measurement on eel's larva, the percentages of head length and preanal length against total length were similar with a conger. Based on the nucleotide sequences, the phylogenetic tree also revealed a close relationship to a conger. Therefore, eel's larva, caught in Namhae from May to June, was identified into a conger's larva.

• Journal of Venture Innovation
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• v.6 no.3
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• pp.131-148
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• 2023

This study analyzed the effect of marketing ability of SMEs using online export marketing on market performance. Small and medium-sized enterprises (SMEs) are making efforts to expand their markets from the domestic market to the overseas market and increase sales. We studied the factors that can produce results in the fiercely competitive overseas market. A total of 400 export SMEs were surveyed, and 159 companies directly participating in online export marketing were selected as final targets. The survey was analyzed using SMART PLS 4.0 and SPSS 26.0 statistical programs, and research hypotheses were verified. The results of the study are as follows. First, it was found that the marketing ability of SMEs had a positive (+) effect on online export marketing. Second, it was confirmed that online export marketing had a significant positive (+) effect on market performance through its mediating role. In addition, the intensity of competition in the export market was found to have a moderating effect in online export marketing. The implications of this study are as follows. The theoretical basis was established that the marketing capabilities (product development capability, distribution capability, pricing capability, public relations capability) of exporting SMEs have a positive effect on overseas market performance through online export marketing. In the market, the use of online export marketing by SMEs can provide implications in that it can be an important means for overseas market development and performance. As a result, it is necessary to actively utilize online export marketing for SMEs to enter overseas markets and achieve results.

• Journal of the Korean Association of Geographic Information Studies
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• v.26 no.4
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• pp.237-250
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• 2023

Orthophotos and DEMs were generated by UAV-based aerial photogrammetry and an attempt was made to apply them to detailed investigations for the production of flood traces. The cultivated area located in Goa-eup, Gumi, where the embankment collapsed and inundated inundation occurred due to the impact of 6th Typhoon Sanba in 2012, was selected as rhe target area. To obtain optimal accuracy of UAV photogrammetry performance, the UAV images were taken under the optimal placement of 19 GCPs and then point cloud, DEM, and orthoimages were generated through image processing using Pix4Dmapper software. After applying CloudCompare's CSF Filtering to separate the point cloud into ground elements and non-ground elements, a finally corrected DEM was created using only non-ground elements in GRASS GIS software. The flood level and flood depth data extracted from the final generated DEM were compared and presented with the flood level and flood depth data from existing data as of 2012 provided through the public data portal site of the Korea Land and Geospatial Informatix Corporation(LX).

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.12 no.2
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• pp.61-72
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• 2007

The relationship between North Pacific chum salmon (Oncorhynchus keta) population and climate variability was investigated in the North Pacific ecosystem. Time-series for the Aleutian Low Pressure, Southern Oscillation, Arctic Oscillation, and Pacific Decadal Oscillation (PDO) indices dating back to 1950 are compared with the chum salmon catch using a cross-correlation function (CCF) and cumulative sum (CuSum) of anomalies. The results of CCF and CuSum analyses indicated that there was a major change in climate during the mid 1970s, and that the chum salmon population responded to this climate event with a time-lag. The PDO and chum salmon returns showed a highly significant correlation with a time-lag of 3 years, while the AOI with a time-lag of $6{\sim}7$ years. The favorable environments for fry chum salmon might cause better growth in the coastal areas, but higher growth rate during the early stage does not seem to be related to the improved return rate of spawning adults. Rather, growth in the Okhotsk Sea or the Bering Sea during immature stages has a significant correlation with return rate, which implies the size-related mortality process. The development of a local climate index is necessary to elucidate the effect of climate variability on the marine ecosystem around the Korean Peninsula.

• Convergence Security Journal
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• v.24 no.2
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• pp.181-188
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• 2024

Amid global geopolitical crises that are heightening tensions worldwide, the importance of national security is being reevaluated. Consequently, South Korea is gaining attention in the global defense market due to its superior technology, competitive pricing, and rapid delivery capabilities. The increasing international demand for defense materials offers opportunities for the development of the domestic defense industry and has the potential to lead to long-term defense strategies and an expansion of exports. In particular, the development of future advanced weapons systems and the expansion of defense exports are likely to be possible through a deep understanding of the international political and economic situation and proactive defense diplomacy. This study analyzes the impact of current global geopolitical crises on Korea's defense industry and presents effective strategies based on these findings, including innovative improvements to defense acquisition systems and the discovery of overseas defense cooperation partners to strengthen defense exports. This strategic approach aims to balance domestic consumption with exports, enhance military strength, and improve the country's standing in the international community. Therefore, efforts are needed to ensure the sustainable growth of the defense industry, enabling South Korea to achieve economies of scale and play a pivotal role in the global defense industry.

• Korean Journal of Ecology and Environment
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• v.57 no.2
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• pp.61-74
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• 2024

Daemadeung, located in the estuary of the Nakdong River, is formed by sand dunes and possesses well-developed intertidal flats. This study aimed to investigate the habitat of benthic microalgae, photosynthetic pigments, and photosynthetic efficiency in the intertidal flats of Daemadeung from January to December 2011. The inorganic nitrogen content in the sediment pore water was primarily composed of ammonium, while nitrate + nitrite was dominant in the upper layer water. The concentration of chlorophyll a and fucoxanthin in the sediment surface was significantly higher than the mean of all the sediment layer. The average Fv/Fm of benthic microalgae during the entire survey period was 0.52±0.03, with the highest value (0.61±0.08) observed in February. The rETR_max showed a seasonal trend, being high from spring to early autumn (April to October) and low from winter to early spring (January to March, November, December), with the highest value (153.05±2.30 µmol electrons m^-2 s^-1) in July and the lowest (38.49±5.17 µmol electrons m^-2 s^-1) in January. The average Fv/Fm of diurnal microalgae was 0.48±0.03, with the highest value (0.61±0.08) observed at noon. The rETR_max showed a highest peak at noon (54.24±11.35 µmol electrons m^-2 s^-1) and reached its lowest point at 16:00 (26.17±4.75 µmol electrons m^-2 s^-1). These findings suggest that the productivity of benthic microalgae varies significantly depending on the survey time and sediment depth. Therefore, to quantify the productivity of benthic microalgae using Diving-PAM, surveys should be conducted based on tidal conditions, and simultaneous pigment analysis of sediment layers should also be performed.

• Journal of Korean Society of Forest Science
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• v.42 no.1
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• pp.83-100
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• 1979

It was planned and performed to study the possibility on the use of inexpensive and easily acquirable foliage powder, which processed by pulverizing after dried, instead of imported expensive wheat flour for the extending of plywood adhesives. Pine leaves of softwood trees, Poplar, Oak and Sycamore leaves of broad leaved species were selected and harvested to pulverize into the minute foliage powder. The harvested foliages from each selected species were pulverized into 40 mesh particles after dried at $100{\sim}105^{\circ}C$ condition during 24 hours in drying oven. To compare the extending effect of plywood adhesives with these foliage powders 100 mesh wheat flour using at current plywood industry was also prepared. Foliage powder and wheat flour were extended into 10, 20, 30, 50 and 100% to the urea and phenol formaldehyde resin. After plywoods were processed by the above extending method shear strength of extended plywoods were analyzed and discussed. The results obtained at this study are as follows: 1) Among 10% extensions of urea formaldehyde resin plywood, dry shear strength of plywood extended by wheat flours was the highest and that of non-extended plywood the next. Plywood extended with foliage powder showed the lowest dry shear strength. The order of dry shear strength of plywoods extended by foliage powder was that of Oak foliage powder extension, the best, that of Sycamore, that of Pine, and that of Poplar. 2) Among 20% extensions of urea formaldehyde resin plywood, plywood extended by wheat flour showed the highest dry shear strength, and the next was plywood by Poplar foliage powder. All these two showed higher dry shear strength than non-extension plywoods. Except Poplar, dry shear strength of foliage powder extension plywoods was bad, but the order of dry shear strength of plywoods extended by foliage powder was Pine, Poplar and Oak. 3) In the case of 30% extensions of urea formaldehyde resin plywood, dry shear strength of wheat flour extension was the highest and non-extension the next. Dry shear strength of foliage powder extension plywoods was poor with a rapid falling-off in strength. 4) Among 50% and 100% extensions of urea formaldehyde resin plywood, only wheat flour showed excellent dry shear strength. In the case of foliage powder extension, low dry shear strength showed at the 50% extension of Pine and Poplar, and plywoods of 50% extension of Oak foliage powder delaminated without measured strength. All plywoods of 100% foliage powder extension delaminated, and then shear strength were not measured. 5) Among wet shear strength of 10% extensions of urea formaldehyde resin plywood, wheat flour extension was the highest as in the case of dry shear strength, and non-extension plywood the next. Except Poplar foliage extension, all foliage powder extension plywoods showed low shear strength. 6) Wet shear strength of plywoods of 20% extension lowered in order of non-extension plywood, plywood of wheat flour extension and plywood of foliage powder extension, but other plywoods of foliage powder extension except plywoods of Poplar and Oak foliage powder extension delaminated. 7) Wet shear strength of 30% or more extension of urea formadehyde resin plywood were weakly measured only at 30% and 50% extension of wheat flour, and wet shear strength of plywoods extended by foliage powder were not measured because of delaminating. 8) Dry shear strength of phenol formaldehyde plywoods extended by 10% wheat flour was the best, and shear strength of plywoods extended by foliage powder were low, but the order was Oak, Poplar, and Pine. Plywood of Sycamore foliage powder extension delaminated. 9) In the case of 20% extensions of phenol formaldehyde resin, dry shear strength of plywood extended by wheat flour was the best, but plywood of Pine foliage powder extension the next, and the next order was Oak and Poplar foliage powder. Plywood of Sycamore foliage powder extension delaminated. 10) Among dry shear strength of 30% extensions of phenol formaldehyde plywood, that of Pine foliage powder extension was on the rise and more excellent than plywood of wheat flour extension, but Poplar and Oak showed the tendency of decreasing than the case of 20% extension. Plywood of Sycamore foliage powder extension delaminated. 11) While dry shear strength of 50% and 100% extension plywoods were excellent in the case of Pine foliage powder and wheat flour extension, that of hardwood such as Poplar, Oak, and Sycamore foliage powder extension were not measured because of delaminating. 12) As a filler the foliage powder extension of urea formaldehyde resin is possible up to 20% with Poplar foliage powder. And also as an extender for phenol formaldehyde resin, Pine foliage powder can be added up to the same amount as that in the case of wheat flour.

• Journal of the Korean Wood Science and Technology
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• v.40 no.3
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• pp.164-176
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• 2012

In the present study, rapeseed flour (RSF), which is a by-product from the production of edible oil and biodiesel extracted from rapeseed, was used to develop alternative adhesives for the production of plywood panels. To examine the effects of the enzyme on the adhesive properties and formaldehyde emission of the RSF-based adhesive resins, three enzymes, such as cellulase (CEL), pectinase (PEC) and protease (ALC), were used either separately or together. As a crosslinking agent, PF prepolymers, which were prepared with 1.5, 1.8 and 2.1 mole formaldehyde and 1 mol phenol (1.8-, 2.1- and 2.4-PF), were added into the RSF hydrolyzates. The adhesive resins formulated with CEL- or CEL-PEC-RSF hydrolyzates and 1.8-F/P PF prepolymers exhibited excellent adhesive strengths and formaldehyde emission. The tensile shear strength and formaldehyde emission of the plywood panels bonded with the formulate resins were satisfied with the minimum requirement of the KS standard for ordinary plywood panels (0.6 N/$mm^2$). In addition, formaldehyde emissions of the plywood panels approached to that of E0 specified in the KS standard (0.5 mg/${\ell}$), and even had much better than those of commercial UF glue mixes. Overall, the use of RSF-based adhesive resins for the production of plywood panels might provide durable adhesive properties and an environmentally friendly substitute for petroleum-based adhesive resins. However, further researches - the increase of solid content of RSF-based adhesives for reducing press time and the microscopic observation of plywood specimen for identifying the relationship between tensile shear strength and the penetration of adhesives into wood structure - are required to commercialize the RSF-based adhesives.