• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.4
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• pp.51-58
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• 2023

In this study, anaerobic co-digestion was carried out using desulfurization sludge and sewage sludge (primary sludge) to evaluate the effects of sulfur compounds in anaerobic digestion. The experiment was carried out in the form of a batch test using 500 mL duran bottle, and the mixing ratio of the feedstock was selected based on the ratio of COD/SO₄. As a result of the experiment, it was confirmed that the amount of biogas generated and the yield decreased at the mixing ratio of COD/SO₄ 20 or less. In particular, below COD/SO₄ 10, it was lower than seed (283.5 mL) which was set without feedstock to correct biogas generated by itself from seed sludge. Methane yield tended to decrease from a ratio of COD/SO₄ 20 or less to 0.135 m³/kg VS compared to 0.396 m³/kg VS of COD/SO₄ 50. In addition, compared to 0.0097 m³/kg VS of hydrogen sulfide yield from COD/SO₄ 50, the ratio of COD/SO₄ 20 increased sharply to 0.0223 m³/kg VS, and in particular, the highest result was 0.0855 m³/kg VS in COD/SO₄ 10. Based on these results, it is judged that the effect of sulfide in anaerobic digestion can have an adverse effect if the COD/SO₄ ratio decreases to less than 20.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.81-88
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• 2022

In the NRC (New paradigm Reinforced Concrete) beam, steel forms, main angles used as main reinforcements, and shear angles used as basic shear reinforcements are welded and assembled in the form of vierendeel truss structures in a steel factory. After the NRC truss frame is installed at the site, additional main reinforcement and shear reinforcement are distributed. In this study, the shear performance evaluation of the NRC beam was conducted through shear tests in accordance with the type of shear reinforcement of the NRC beam (shear angle, inclined shear reinforcing bar, and U-type cover bar). As a result of the test, the initial stiffness was similar before the initial cracking of each specimen, and all specimens were shear fractured.The shear reinforcements of the specimens exhibited a yielding behavior at the time of the maximum sheat force, and the shear strengths of the specimens increased as the amount of reinforcement of the shear reinforcement increased. These results show that NRC shear reinforcements exhibit shear performance corresponding to their shear strength contribution. As a result of calculating the nominal shear strengths according to KDS 14 20 22, the experimental shear strengths of the NRC beam specimens with shear reinforcement was 37~146% larger than the nominal shear strengths, so It was evaluated as a safety side.

• Ecology and Resilient Infrastructure
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• v.9 no.2
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• pp.93-99
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• 2022

It was confirmed that the fish diversity decreased with increasing index of weir's density (IWD) in the four river systems. The IWD showed difference with watershed, it was high in the Nakdong River (NDR). Both two river systems of Gum River (GUR) and Yeongsan River (YSR) were similar, whereas relatively lower density observed in the Han River (HNR) system. A result of 2-Dimensional Kolmogorov-Smirnov (2-DKS) as a nonparametic test showed different threshold values affecting fish diversity with the river systems. The p-values based on D_max, were significantly different at 0.05 level (except for YSR). The threshold values affecting fish diversity were also different with watershed. The values were 1.6/km of the HNR, 1.3/km of the NDR, and 2.3/km of the GUR, respectively. The fish diversity was decreased when IWD is over threshold values. The IWD of total 404 rivers (about 33%) among 1,217 surveyed in this study showed above threshold value. These rivers should be considered first for evaluating river continuity. The IWD and threshold value suggested in this study would be useful for selecting a stream priority for river connectivity study.

• Ecology and Resilient Infrastructure
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• v.9 no.2
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• pp.100-106
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• 2022

The relationships between river length and weir density versus fish species observed were analyzed for 210 local rivers in the Seomjin River system (SJR). A nonlinear exponential relationship between river length and number of fish species were observed. Model coefficient was 0.03 and coefficient of determinant (R²) was 0.59, meaning that about 59.0% of total variance was explained by river length variable. Predicted value by model and observed number of species showed a difference. About 110 local rivers (about 52.4%) showed lower value than predictive value. The average index of weir's density (IWD) in the SJR was about 2.7/km, which was significantly higher than that of other river basins. As a result of nonparametric 2-Kimensional Kolmogorov-Smirnov (2-DKS) analysis based on the IWD, the threshold value affecting fish diversity was about 2.5/km (D_max=0.048, p<0.05). Above the threshold value, it means that the number of fish species would be decreased. In fact, the ratio of the expected species to the observed species was lowered to less than 70%, when the IWD is higher than the threshold value. To maintain aquatic ecological connectivity in future, it is necessary to manage IWD below the threshold value.

• Korean Journal of Remote Sensing
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• v.38 no.6_1
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• pp.1329-1341
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• 2022

Destroying the marine environment and marine ecosystem and causing marine accidents, marine debris is generated every year, and among them, submerged marine debris is difficult to identify and collect because it is on the seabed. Therefore, deep-learning-based semantic segmentation was experimented on waste fish nets and waste ropes using underwater images to identify efficient collection and distribution. For segmentation, a high-resolution network (HRNet), a state-of-the-art deep learning technique, was used, and the performance of each optimizer was compared. In the segmentation result fish net, F1 score=(86.46%, 86.20%, 85.29%), IoU=(76.15%, 75.74%, 74.36%), For the rope F1 score=(80.49%, 80.48%, 77.86%), IoU=(67.35%, 67.33%, 63.75%) in the order of adaptive moment estimation (Adam), Momentum, and stochastic gradient descent (SGD). Adam's results were the highest in both fish net and rope. Through the research results, the evaluation of segmentation performance for each optimizer and the possibility of segmentation of marine debris in the latest deep learning technique were confirmed. Accordingly, it is judged that by applying the latest deep learning technique to the identification of submerged marine debris through underwater images, it will be helpful in estimating the distribution of marine sedimentation debris through more accurate and efficient identification than identification through the naked eye.

• Korean Journal of Organic Agriculture
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• v.31 no.4
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• pp.395-412
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• 2023

The morphology and whole genome sequence of Hyphantria cunea nucleopolyhedrovirus W1 (HycuNPV-W1) isolated in Korea were analyzed for the use as an eco-friendly control agent against H. cunea. The HycuNPV-W1 had irregular tetrahedral polyhedra with a size of 1.5-2.2 ㎛ which is similar to that of previously reported HycuNPV isolated in Korea. As a result of whole viral genome analysis, HycuNPV-W1 was composed of 131,353 bp, which is 1,606 bp shorter than that of the previously reported HycuNPV. The G+C content was 45% and six of the homologous repeated regions were found, so there was no significant difference from the previous report. As a result of ORF analysis, HycuNPV-W1 contains total of 145 ORFs which is three ORFs less than the previous report, while two ORFs were exclusively found in HycuNPV-W1. The functions of these ORFs remains unclear and are not considered to have a significant influence on the characteristics of the HycuNPV. The genome vista analysis showed that the overall sequence identity between HycuNPV-W1 and the previously reported HycuNPV was very high. The whole genome of HycuNPV-W1 analyzed was found to be similar to those of the previously reported HycuNPV, however, it is supposed to be a novel resource in Korea with different isolate.

• Journal of Convergence for Information Technology
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• v.12 no.3
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• pp.244-251
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• 2022

This study attempted to investigate the applicability of Geranium maculatum extract as a cosmeceutical ingredient. For this, DPPH, ABTS and FRAP assays were performed to assess radical scavenging activities. To evaluate antioxidant substances, in addition, polyphenol and flavonoid concentrations were measured. Furthermore, cytotoxicity, whitening and anti-inflammatory tests were conducted, using B16F10 and RAW 264.7 cells, and the results found the followings: In the DPPH and ABTS assays, 265.8 mg ascorbic acid/g and 168.5 mg ascorbic acid/g of antioxidant capacities were found respectively. According to the FRAP assay, 1 mg Geranium maculatum extract was same with ascorbic acid 229±9 ㎍ in terms of reducing power. In polyphenol and flavonoid concentrations, 32.989±1.610 mg/g and 11.098±0.261 mg/g were observed each. The above results show that cells survived in the test concentrations more than 80 percent, confirming the low toxicity of Geranium maculatum extract. According to whitening testing, melanin synthesis was reduced depending on concentration, and at the same time, 40.62±2.07% of melanin production inhibition was found at 100 ㎍/mL. In anti-inflammatory testing, inflammation was reduced depending on concentration, and 27.86±2.82% of inhibition of inflammation was detected simultaneously, confirming the applicability of Geranium maculatum extract as a cosmeceutical ingredient.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.26 no.4
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• pp.343-355
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• 2021

Eelgrass, Zostera marina L., was widely distributed around Sinyangseopji Beach in Bangdu Bay, on the eastern coast of Jeju Island, until breakwater construction in the late 1990s resulted in its complete loss. Six experimental sites were identified for restoration of the Z. marina bed in Bangdu Bay. Using the staple method, 500 Z. marina shoots were transplanted at each site in January 2019 and 2020. The transplants, along with environmental parameters, were monitored for 10 months following transplantation. There were significant differences in underwater irradiance, water temperature, and salinity among the sites, but all were suitable for Z. marina growth. The Ulva species, an opportunistic alga, appeared in spring and accumulated during summer at all sites; however, there was no significant effect of Ulva species on the survival and growth of the eelgrass transplants. Most of the transplanted Z. marina survived, and after 3 months, the density increased by 112.5-300% due to vegetative propagation, with a rapid rate of increase observed during spring and early summer at all sites. For 1-2 months after transplanting, the Z. marina shoots showed signs of transplant shock, after which the shoot density increased at all sites, confirming that all transplants adapted well to the new environment. However, in both 2019 and 2020, during late summer to early fall, the sites experienced heavy damage from typoons (twice in 2019 and three times in 2020) that hit Bangdu Bay. The transplants at two sites located in the center of Bangdu Bay were completely destroyed, but those at three sites located to the west of the bay showed a 192-312% increase in density. Thus, we confirmed that the Bangdu Bay Z. marina bed can be restored, with the highest probability of success for Z. marina restoration on the western side of Bangdu Bay, which is protected from typhoons.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.11 no.5
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• pp.175-188
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• 2016

This study is intended to look into the effects of project managers' leadership on participants' individual competency and project performance. To achieve this, a survey was empirically carried out to a sample of 276 researchers who are working on a project with a research and development group in private R&D centers. The results of this study were summarized as follows. First, the leadership competency of project managers had a significant positive effect on the individual competency of project participants. Second, the leadership competency of project managers had a significant positive effect on the project management performance. Third, the leadership competency of project managers had no significant effect on the project completion performance. Fourth, the individual competency of project participants had a significant positive effect on the project management performance. Fifth, the individual competency of project participants had no significant effect on the project completion performance. Sixth, the project management performance had a significant positive effect on the project completion performance. Seventh, the project completion performance was indirectly mediated in the effect of project managers' leadership competency on project completion performance. Eighth, the project management performance was indirectly mediated in the effect of project participants' individual competency on project completion performance. Based on the findings stated above, a combination of project management performance can generate better results in the effect of project participants' individual competency on project completion performance.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.566-566
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• 2016

정부의 4대강 물 관리 종합대책에 따르면, 수계 전체 오염원중 비점오염원이 차지하는 오염부하가 22~37%에 달하는 것으로 추정되고 있다. 하지만 이러한 중요성에도 불구하고 농업지역 비점오염물질 저감을 위한 대책은 논과 밭과 같이 농경지에 관한 것이 대부분이었으며, 축산은 관리 기준의 가장 기초라고 할 수 있는 지목분류기준에 조차 별도의 기준이 없는 실정이다. 가축분뇨공공처리시설과 가축분뇨자원화시설은 가축분뇨를 처리하여야 하는 점오염원이지만, 차량 운반시 발생되는 일부 분뇨와 처리장 세척 시 발생되는 일부 오염물질들이 비점오염원으로 작용하고 있으며 이에 대한 관리가 미흡한 실정이다. 따라서 본 연구에서는 가축분뇨공공처리시설과 가축분뇨자원화시설에서 강우시 발생되는 유출특성을 분석하였으며, 이를 통해 가축분뇨처리시설의 비점오염 관리 처리시설 설치 시에 중요한 기초자료로 활용하고자 한다. 본 연구에서는 경상북도 영천시, 경기도 용인시, 전라북도 정읍시, 강원도 횡성군 등 축산밀집 지역을 대상으로 연 5회 강우시 모니터링을 실시하였으며, 모니터링자료를 바탕으로 유량가중평균농도(Event Mean Concentration, EMC)를 산정하였다. 영천시 가축분뇨자원화시설의EMC 산정결과 평균 BOD 5.1 mg/L, TN 6.90 mg/L, TP 0.91 mg/L로 산정되었으며, 용인시 개별처리농가의 경우 BOD 6.8 mg/L, TN 3.74 mg/L, TP 1.04 mg/L로, 횡성군 가축분뇨공공처리장의 경우 BOD 4.5 mg/L, TN 3.56 mg/L, TP 1.60 mg/L로, 정읍시 가축분뇨공공자원화시설의 경우 BOD 4.3 mg/L, TN 6.82 mg/L, TP 0.48 mg/L로 산정되었다. BOD, TN은 영천시 가축분뇨자원화시설에서 가장 높게 나타났고, TP의 경우 횡성군 축산폐수공공처리장의 경우 높게 나타났다. 유출특성을 분석한 결과 가축분뇨자원화시설의 경우 대부분 콘크리트 기반으로 조성된 토지위에 조성되어 강우시 유량은 급격하게 상승하며, 강우가 종료되면 바로 감소하는 불투수층 지역의 특성을 나타났다. 본 연구에서 분석된 유츨특성과 EMC는 비점오염 처리시설이나 가축분뇨공공처리시설 설치시 기초데이터로 활용이 가능할 것으로 판단되며, 향후 가축분뇨처리시설의 지속적인 모니터링과 모니터링지점 확대로 자원화시설 강우유출수의 DataBase화를 통한 지속적인 연구 및 관리가 되어야 할 것으로 판단된다.