• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.spc
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• pp.23-29
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• 2022

To detect harmful chemical substances in seawater, we fabricated a prototype sensor and evaluated its performance. The prototype sensor consisted of a detector, housing, and driving circuit. We built the detector by printing an Indium-Tin-Oxide (ITO) nanoparticle film on a flexible substrate, and it had two detection parts for simultaneous detection of temperature and HNS concentration. The housing connected the detector and the driving circuit and was made of Teflon material to prevent chemical reactions that may affect sensor performance. The driving circuit supplied electric power, and display measured data using a bridge circuit and an Arduino board. We evaluated the sensor performances such as response (ΔR), the limit of detection (LOD), response time, and errors to confirm the specification.

• Journal of the Korean Geotechnical Society
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• v.38 no.3
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• pp.35-42
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• 2022

The N-value from the Standard Penetration Test (SPT), which is one of the representative in-situ test, is an important index that provides basic geological information and the depth of the bearing layer for the design of geotechnical structures. In the aspect of time and cost-effectiveness, there is a need to carry out a representative sampling test. However, the various variability and uncertainty are existing in the soil layer, so it is difficult to grasp the characteristics of the entire field from the limited test results. Thus the spatial interpolation techniques such as Kriging and IDW (inverse distance weighted) have been used for predicting unknown point from existing data. Recently, in order to increase the accuracy of interpolation results, studies that combine the geotechnics and deep learning method have been conducted. In this study, based on the SPT results of about 22,000 holes of ground survey, a comparative study was conducted to predict the depth of the bearing layer using deep learning methods and IDW. The average error among the prediction results of the bearing layer of each analysis model was 3.01 m for IDW, 3.22 m and 2.46 m for fully connected network and PointNet, respectively. The standard deviation was 3.99 for IDW, 3.95 and 3.54 for fully connected network and PointNet. As a result, the point net deep learing algorithm showed improved results compared to IDW and other deep learning method.

• Journal of agriculture & life science
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• v.50 no.1
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• pp.117-124
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• 2016

Researches on soil microbial community are increasing to assess ecosystem responses to anthropogenic disturbances and to provide an indicator of ecosystem recovery. Microbial communities are able to respond more rapidly to environmental changes than plants and therefore they may provide an early indication of the ecosystem recovery trajectory. This study was conducted using 16S rRNA gene pyrosequencing of soil samples to compare soil bacterial community composition between artificially covered soils of the Baedudaegan ridgeline and their adjacent forest soils in two restoration project sites, Ihwaryeong and Yuksimnyeong, which were completed in 2012 and 2013, respectively. Richness of the Phylum level was 29.3 in Ihwaryeong and 32.3 in Yuksimnyeong. Significant difference in the richness between artificial restored soils and adjacent forest soils(p<0.01) was observed, however no significant difference was observed for site location and soil depth. Acidobacteria(37.3%) and Proteobacteria(31.1%) were more abundant than any other phylum in collected soil samples. Also, we found the significant difference in the relative abundance of the two abundant phyla between artificially restored soils and their adjacent forest soils (Proteobacteria, 38.1% in restored soils vs 24.2% in adjacent forest soils, p<0.01; Acidobacteria, 55.4% in restored soils vs 19.2% in adjacent forest soils, p<0.001). The results support the previous researches indicating that soil bacterial community composition is affected by nutritional status of soils and that Acidobacteria is also strongly influenced by pH, thus favoring soils with lower pH. This study could be utilized to monitor and evaluate restoration success of forest soil environment quantitatively.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.3B
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• pp.283-296
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• 2008

The Urban Stream Assessment Technique (USAT) was suggested to give information about present urban stream condition. Domestic and foreign stream evaluation methods were analyzed and some streams were previously investigated to decide evaluation factors that could evaluate stream condition and have concern with characteristics and flood control of urban stream. The USAT consisted of three steps. High step has three characteristics concerned with functions of stream such as flood risk, stream, and ecology. In middle step, three characteristics were subdivided by ten features to describe changes and degradations of urban stream. Low step consisted of fifty three factors that explain the present condition of ten features. A survey of river experts was conducted to reflect weight among characteristics and features. The weights were calculated by analytic hierarchy process(AHP). The USAT was carried out to check over application of that in Suwon, Anyang, and Joongrang stream. The results of stream evaluation were expressed by factor index, feature index, characteristic index, total index, and evaluation grade. The results of the USAT were useful to realize changed and degraded areas. It is expected that the USAT can be used as base investigation for restoring and managing urban streams.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.5B
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• pp.487-495
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• 2010

Soil moisture is a crucial factor in hydrological system which influences runoff, energy balance, evaporation, and atmosphere. United States National Aeronautic and Space Administration (NASA) and Department of Agriculture (USDA) have established Soil Moisture Experiment (SMEX) since 2002 for the global observations. SMEX provides useful data for the hydrological science including soil moisture and hydrometeorological variables. The purpose of this study is to investigate the relationship between remotely sensed soil moisture data from aircraft and satellite and ground based experiment. C-band of Polarimetric Scanning Radiometer (PSR) that observed the brightness temperature provides soil moisture data using a retrieval algorithm. It was compared with the In-situ data for 2-30 cm depth at four sites. The most significant depth is 2-10 cm from the correlation analysis. Most of the sites, two data are similar to the mean of data at 10 cm and the median at 7 cm and 10 cm at the 10% significant level using the Rank Sum test and t-test. In general, soil moisture data using the C-band of the PSR was established to fit the Normal, Log-normal and Gumbel distribution. Soil moisture data using the aircraft and satellites will be used in hydrological science as fundamental data. Especially, the C-band of PSR will be used to prove soil moisture at 7-10 cm depths.

• Journal of the Korean Institute of Landscape Architecture
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• v.51 no.5
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• pp.44-56
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• 2023

This research explores the enhancement of park operation and management by analyzing the changing demands of park users. While traditional methods depended on surveys, there has been a recent shift towards utilizing social media data to understand park usage trends. Notably, most research has focused on text data from social media, overlooking the valuable insights from image data. Addressing this gap, our study introduces a novel method of assessing park usage using social media image data and then applies it to actual city park evaluations. A unique image analysis tool, built on Visual Question Answering (VQA) deep learning technology, was developed. This tool revealed specific city park details such as user demographics, behaviors, and locations. Our findings highlight three main points: (1) The VQA-based image analysis tool's validity was proven by matching its results with traditional text analysis outcomes. (2) VQA deep learning technology offers insights like gender, age, and usage time, which aren't accessible from text analysis alone. (3) Using VQA, we derived operational and management strategies for city parks. In conclusion, our VQA-based method offers significant methodological advancements for future park usage studies.

• Journal of Environmental Science International
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• v.32 no.12
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• pp.899-914
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• 2023

Various seeding materials for cloud seeding are being used, and sodium chloride powder is one of them, which is commonly used. This study analyzed the experimental results of multi-aircraft cloud seeding in connection with Republic of Korea Air Force (CN235) and KMA/NIMS(Korea Meteorological Administration/National Institute of Meteorological Sciences) Atmospheric Research Aircraft. Powdered sodium chloride was used in CN235 for the first time in South Korea. The analysis of the cloud particle size distributions and radar reflectivity before and after cloud seeding showed that the growth efficiency of powdery seeding material in the cloud is slightly higher than that of hygroscopic flare composition in the distribution of number concentrations by cloud aerosol particle diameter (10 ~ 1000 ㎛). Considering the radar reflectivity, precipitation, and numerical model simulation, the enhanced precipitation due to cloud seeding was calculated to be a maximum of 3.7 mm for 6 hours. The simulated seeding effect area was about 3,695 km², which corresponds to 13,634,550 tons of water. In the precipitation component analysis, as a direct verification method, the ion equivalent concentrations (Na⁺, Cl^-, Ca²⁺) of the seeding material at the Bukgangneung site were found to be about 1000 times higher than those of other non-affected areas between about 1 and 2 hours after seeding. This study suggests the possibility of continuous multi-aircraft cloud seeding experiments to accumulate and increase the amount of precipitation enhancement.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2021.04a
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• pp.17-17
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• 2021

곰취는 주로 쌈용, 장아찌, 나물용 등으로 이용되고 있으며 주로 자생 곰취의 일종인 '곤달비' 라고 하는 종이 많이 재배되고 있다. 일반 곰취에 비해 곤달비는 향이 진하지 않고 씁쓸한 맛이 적어 인기가 많은 종이다. 또한 농가에서는 엽수가 많아 수량이 높기 때문에 재배를 선호하게 된 종이기도 하다. 그러나 곤달비는 수확후 여름을 지나면서 고온건조기에 흰가루병과 식물체가 위축되는 로젯현상으로 잎이 작고 진록색으로 되거나 고사하여 다음해의 수량을 저하시키는 원인이 되고 있다. 이렇게 2~3년 재배를 하면 연작장애와 더불어 결주가 생기기 시작하고 수량이 급격히 감소하는 문제가 발생되는 실정이다. 이러한 문제점을 해결하기 위하여 흰가루병에 저항성이면서 세력이 우수한 한대리곰취와 일반곰취를 교배하여 흰가루병에 강하고 수량성이 뛰어난 계통을 선발하여 그 동안 '쌈마니', '다목이', '곰마니', '수마니', '그린베어' 등 5품종을 육성한 바 있다. 이번에는 용도 다양화를 위하여 잎이 매우 커서 김밥처럼 곰취 밥말 이용을 선발하여 품종을 만들고자 하였다. '대마니' 품종은 2007년 7월에서 9월까지 인공교배를 하여 종자를 얻었으며 2008년 3월에 파종하여 육묘후 포장에 정식하여 생육관리를 하였다. 2013년 생육 및 수량특성 조사에서 일반적으로 많이 재배되는 '곤달비' 종보다 우수한 7033-1번 개체를 선발하였다. 선발된 7033-1번 개체는 2014년부터 2020년까지 노지포장에서 증식되면서 고농G-7호로 계통화 되었으며 2019년부터 2년간의 생육특성 검정을 통하여 최종 선발하였다. 그리고 2020년 농작물직무육성 품종선정위원회에서 신품종으로 선정되어 '대마니(Daemani)'로 명명되었다. '대마니' 품종의 특성은 엽병귀의 색이 연녹색을 띠고 엽병에 털이 있으며 잎 뒷면에 털은 없으나 광택이 없고. 엽맥밀도는 보통이다. 쌈용, 데침쌈용, 묵나물용으로 이용이 가능하다. 특히 엽장과 엽폭이 39cm와 49cm로 '잎이 커서 밥말이용으로 적당하다. 주당 엽수는 54개로 '쌈마니' 품종보다 매우 적다. 주당 수량은 4,961g 으로 '쌈마니' 1,362g 보다 3배 정도 많았다. 추대시는 8월 28일, 개화시는 9월 16일로 '쌈마니' 품종보다 약 6일 정도 늦었다. 흰가루병 저항성 정도는 '쌈마니' 품종의 중도 저항성에 비하여 전혀 병에 감염되지 않는 강한 저항성을 보였다. 이와 같은 특성의 흰가루병 저항성 품종이고 잎이 큰 '대마니' 품종이 농가에 보급되어 출하된다면 밥말이용 등 용도다양화를 통한 새로운 소비창출이 가능할 것으로 기대된다.

• Journal of Korean Society of Forest Science
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• v.112 no.4
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• pp.523-529
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• 2023

The aim of this study was to analyze the potential for timber harvesting in the Hongchoen Garisan Leading Forest Management Complex in the national forests, and to suggest an optimal target yield for sustainable timber harvesting. The potential for timber harvesting was assessed by analyzing the area available for timber harvesting using GIS spatial analysis, but excluding areas with a slope of more than 40° (topographical constraints), areas within 30 m on both sides of streams (environmental constraints), and areas more than 300 m away from forest roads (technical constraints). The analysis identified 3,298 ha (49%) of the total complex area of 6,679 ha as available for timber harvesting, yielding a potential harvesting volume of 608,613 m³. In the case of coniferous plantations, the potential harvesting volume was 409,721 m³, which was a very high level that accounted for 67.3% of the total. We also conducted an optimization analysis to minimize the differences in area between age classes, while maintaining sustainable timber harvesting for the next 50 years. An annual average of 41.9 ha (7,988 m³) was determined to be the optimal timber yield, and in this case, it was possible to convert the age class structure to a more stable structure after 50 years.

• Journal of Internet Computing and Services
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• v.24 no.6
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• pp.119-125
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• 2023

Through the Ukraine-Russia war, the military importance of drones is being reassessed, and North Korea has completed actual verification through a drone provocation towards South Korea at 2022. Furthermore, North Korea is actively integrating artificial intelligence (AI) technology into drones, highlighting the increasing threat posed by drones. In response, the Republic of Korea military has established Drone Operations Command(DOC) and implemented various drone defense systems. However, there is a concern that the efforts to enhance capabilities are disproportionately focused on striking systems, making it challenging to effectively counter swarm drone attacks. Particularly, Air Force bases located adjacent to urban areas face significant limitations in the use of traditional air defense weapons due to concerns about civilian casualties. Therefore, this study proposes a new passive air defense method that aims at disrupting the object detection capabilities of AI models to enhance the survivability of friendly aircraft against the threat posed by AI based swarm drones. Using laser-based adversarial examples, the study seeks to degrade the recognition accuracy of object recognition AI installed on enemy drones. Experimental results using synthetic images and precision-reduced models confirmed that the proposed method decreased the recognition accuracy of object recognition AI, which was initially approximately 95%, to around 0-15% after the application of the proposed method, thereby validating the effectiveness of the proposed method.