• Journal of Plant Biotechnology
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• v.46 no.3
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• pp.205-216
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• 2019

Since the RNA interference (RNAi) had been discovered in many organisms, small non-coding RNA-mediated gene silencing technology, including RNAi have been widely applied to analysis of gene function, as well as crop improvement. Despite the usefulness of RNAi technology, RNAi transgenic crops have various potential environmental risks, including off-target and non-target effects. In this study, we developed methods that can be effectively applied to environmental risk assessment of RNAi transgenic crops and verified these methods in 35S::dsRNAi_eGFP rice transgenic plant we generated. Off-target genes, which can be non-specifically suppressed by the expression of dsRNAi_eGFP, were predicted by using the published web tool, pssRNAit, and verified by comparing their expressions between wild-type (WT) and 35S::dsRNAi_eGFP transgenic rice. Also, we verified the non-target effects of the 35S:: dsRNAi_eGFP plant by evaluating horizontal and vertical transfer of small interfering RNAs (siRNAs) produced in the 35S::dsRNAi_eGFP plant into neighboring WT rice and rhizosphere microorganisms, respectively. Our results suggested that the methods we developed, could be widely applied to various RNAi transgenic crops for their environmental risk assessment.

• Journal of Wetlands Research
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• v.21 no.2
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• pp.95-101
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• 2019

In tidal flats that lack plants, methane ($CH_4$) fluxes are both positive (gas emission) and negative (gas "sinking") in nature. The levels of methanotroph populations significantly affect the extent of $CH_4$ sinking. This preliminary study examined $CH_4$ flux in tidal flats using a circular closed-chamber method to understand the effects of macroinvertebrate burrowing activity. The chamber was deployed over decapods (mud shrimp, Laomedia astacina and crab, Macrophthalmus japonicus) burrows for ~ 2 h, and the $CH_4$ and $CO_2$ concentrations were continuously monitored using a closed, diffuse $CH_4/CO_2$ flux meter. We found that Laomedia astacina burrow (which is relatively long) site afforded higher-level $CH_4$ production, likely due to diffusive emission of $CH_4$ in deep-layer sediments. In addition, the large methanotrophic bacteria population found in the burrow wall sediments has $CH_4$ oxidation (consumption) potential. Especially, nitrite-driven anaerobic oxidation of methane (AOM) may occur within burrows. The proposed $CH_4$-oxidation process was supported by the decrease in the ${\delta}^{13}C$ of headspace $CO_2$ during the chamber experiment. Therefore, macroinvertebrate burrows appear to be an important ecosystem environment for controlling atmospheric $CH_4$ over tidal flats.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.29-36
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• 2019

This study investigated the self-healing properties of blast furnace slag cement paste sample with $Na_2SO_4$ as a blast furnace slag activator after conducting the permeability test. Self-healing properties were examined by crack filling ratio and quantification of self-healing products. The degree of self-healing was evaluated by the crack filling ratio, and the crack filling ratio was analyzed by panoramic analysis using BSE-DIP for objectivity. The average crack filling ratio showed a tendency of decreasing from the upper part of the specimen to the lower part as the average of the top part was 18%, the middle part was 7% and the bottom part was 5% on average. The maximum crack filling ratio was 44% and the minimum crack filling ratio was 3%. The residual self-healing product after the permeability test contained a large amount of Ca element and Al element derived from the blast furnace slag, and the Si element was mainly present near the crack surface. The most abundant minerals in self-healing products were about 68% C-A-H. $CaCO_3$ was about 13% and C-A-S-H was about 8%. Three minerals accounted for 90% of self-healing products. C-A-H was mainly present at a part slightly distant from the crack surface and showed an angular or acicular shape. The C-A-S-H was generated on the surface naturally connected to the existing specimen, and the $CaCO_3$ was generally observed on the surface of the specimen or the inside of the crack.

• Journal of the Korean Geosynthetics Society
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• v.18 no.1
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• pp.67-77
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• 2019

The grouting method is utilized to reinforce and waterproof poor grounds, enhance the bearing capacity of structures damaged resulting from settlement due to elevation and vibration or differential settlement, and for cutoff. The purpose of this research is to enhance the compressive strength of grout materials by using aramid fiber and develop a high-strength ground improvement method by using blast furnace slag powder. In this regard, this study has conducted a uniaxial compression test after checking the high charge (higher than 50%) of the ratio of blast furnace slag powder and cement at 100:0, 70:30 and 40:60%, adding the aramid mixture based on 0, 0.5 and 1.0% of the cement and furnace slag powder weight and creating sand gels based on surface oiling rate of 0.7 and 1.2%. For the environmental review evaluation, a heavy metal exudation test and a pH test measurement have been conducted. The experiment results showed that 1% increase of aramid fiber led to 1.3 times greater uniaxial compression intensity. As for the hexavalent chrome, a 30% increase in blast furnace slag powder led to approximately 50% decrease in heavy metal exudation. However, the pH test revealed that a 30% increase in blast furnace slag powder resulted in approximately 0.5 increase in pH. Further research on the pH part is needed in the future.

• Korean Journal of Veterinary Service
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• v.42 no.1
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• pp.1-7
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• 2019

Porcine reproductive and respiratory syndrome (PRRS) is economically the most important and challenging disease in swine industries worldwide and caused by PRRS virus (PRRSV). Previous studies reported that pigs with heterozygous genotypes in the guanylate-binding proteins (GBP1 and GBP5) exhibited increased resistance against PRRSV infection. The present study was conducted to produce higher numbers of the heterozygous pigs based on the PRRS resistant polymorphisms found in GBP1 (GBP1E2 and WUR) and GBP5, and evaluate the resistance of heterozygous pigs against challenge with a type 2 PRRSV (JA142) in comparison with homozygous pigs. In the challenge study, 12, 4 week-old PRRSV-negative piglets were selected based on the genotypes of the 3 polymorphisms (GBP1E2, WUR and GBP5). Among them, 8 piglets [homozygous (n=4) and heterozygous (n=4)] were challenged with JA142 and kept in the same room, and the remaining 4 piglets were kept separately as a negative control. In results, the sperms collected from the boars of GBP1E2-GG genotype produced approximately 28~41% higher numbers of heterozygous piglets as compared with those from the boars of GBP1E2-AG genotype. In the challenge study, we found that heterozygous piglets showed the significantly lower levels of viremia than homozygous piglets at 14, 21 and 28 dpc. Consistently, these heterozygous piglets also exhibited significantly higher ADWG than homozygous piglets. Therefore, in the current study, selection of boars based on SNP markers could increase the production of PRRS resistant piglets and the PRRS resistant pigs were found to be more resistant to PRRSV infection.

• Korean Journal of Remote Sensing
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• v.35 no.2
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• pp.229-239
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• 2019

All vegetation colonies have layered structure. This layer is called 'forest vertical structure.' Nowadays it is considered as an important indicator to estimate forest's vital condition, diversity and environmental effect of forest. So forest vertical structure should be surveyed. However, vertical structure is a kind of inner structure, so forest surveys are generally conducted through field surveys, a traditional forest inventory method which costs plenty of time and budget. Therefore, in this study, we propose a useful method to classify the vertical structure of forests using remote sensing aerial photographs and machine learning capable of mass data mining in order to reduce time and budget for forest vertical structure investigation. We classified it as SVM (Support Vector Machine) using RGB airborne photos and LiDAR (Light Detection and Ranging) DSM (Digital Surface Model) DTM (Digital Terrain Model). Accuracy based on pixel count is 66.22% when compared to field survey results. It is concluded that classification accuracy of layer classification is relatively high for single-layer and multi-layer classification, but it was concluded that it is difficult in multi-layer classification. The results of this study are expected to further develop the field of machine learning research on vegetation structure by collecting various vegetation data and image data in the future.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.11
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• pp.25-34
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• 2019

It is important to design windows in a reasonable way considering the performance characteristics of the elements of the window rather than just to increase the thermal energy performance of the window. In this study, the Heat-transfer Coefficient as insulation performance of the windows and together with the grade of the glass's SHGC (Solar Heat Gain Coefficient) were analyzed to relate to the energy efficiency performance of the building by azimuth angle. Based on this basic study, the Heat-transfer Coefficient of windows and the SHGC rating of glass were applied to the unit plan of apartment building, and the Heating and Cooling Demand were analyzed by azimuth angle. Apartment plan types were divided into 2 types of Non-extension and extension of balcony. The designPH analysis data derived from the variant of the Heat-transfer Coefficient and SHGC, were put into PHPP(Passive House Planning Package) to analyze precisely the energy efficiency(Heating and Cooling Demands) of the building by azimuth angle. In addition, assuming the 'ㅁ' shape layout, energy efficiency performance and potential of PV Panel installation also were analyzed by floors and azimuth angle, reflecting the shading effects by surrounding buildings. As the results of the study, the effect of Heat Gain by SHGC was greater than Heat Loss due to the Heat-transfer Coefficient. So it is more effective to increase SHGC to satisfy the same Heating Demand, and increasing SHGC made possible to design windows with low Heat-transfer Coefficient. It was also revealed that the difference in annual Heating and Cooling Demands between the low, mid and high floor households is significantly high. In addition to it, the installation of PV Panel in the form of a shading canopy over the window reduces the Cooling Load while at the same time producing electricity, and also confirmed that absolute thermal energy efficiency could not be maximized without controlling the thermal bridge and ventilation problems as important heat loss factors.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.1
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• pp.119-131
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• 2021

This study quantitatively derived the direct socio-economic effects of the Gyeongbu Expressway, which opened in 1970, and suggested a methodological approach for more reliable results. The scenario was set when the Gyeongbu Expressway was not constructed in 1970, the opening of the Gyeongbu Expressway was delayed by 10 years, and the toll road between Seoul and Daejeon, or between Seoul and Gangneung was opened instead of the Gyeongbu Expressway as suggested by the World Bank. In addition, direct benefits were estimated by calculating and comparing the current vehicle operating costs, travel time costs, traffic accident costs, and environmental pollution costs. As a result, it was estimated that about 351 trillion won in direct benefits occurred, and it can be seen that the promotion of the construction project of the Gyeongbu Expressway at that time had a huge impact on South Korea's social economy.

• Korean Journal of Construction Engineering and Management
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• v.22 no.2
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• pp.63-71
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• 2021

This paper looks into how to enhance construction project management, focusing on the change order, which is often considered one of the major causes for construction delays, disputes, and claims in the middle east construction. First, this paper categorizes the major causes of change orders. It suggests a detailed classification standard for affecting factors resulting from change orders based on a case study result of an on-going construction project in the Middle East. In particular, this paper presents a method to apply a machine learning-based feature selection to quantify the importance of change order triggers and affecting factors. As a result, the case study identifies six major change order triggers and eight affecting factors. Also, a meaningful relationship between change order triggers and affecting factors by each category is presented. This paper will contribute to setting a clear guideline for change order management for the international plant construction field while helping prevent construction delays and cost run-ups by reducing the time required for change order resolution between project owners and contractors.

• 한국사회정책
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• v.23 no.2
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• pp.141-172
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• 2016

This study examines the employment conditions and labour experience of elementary after-school care teachers in South Korea. Based on the empirical data collected through in-depth interviews with after-school care teachers in Gwangju Metropolitan City, the study considers multifaceted problems faced by after-school care teachers in their workplace. The after-school care class is part of educational policies initiated and rapidly expanded by the Ministry of Education, resulting in the substantial increase of non-regular school workers. The irregularization of after-school care teachers illustrates that the common problems faced by female non-regular workers, such as social discrimination, exclusion and inequality, are also transplanted into the typical public sector. In the case of Gwangju Metropolitan City, during the past two years there have been evident increases both in under 15-hour short time contract care teachers and outsourcing of care classes. Temporary part-time contract care teachers suffer relentless job insecurity and experience poor working conditions, exclusion and discrimination within the workplace and labour alienation. In order to minimize the organized resistance of care teachers, school authorities implicitly individualize and isolate care teachers through hierarchization, the division of labour and the spatial division of classes between indefinite and temporary contract teachers.