• 한국항공우주학회지
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• 제50권1호
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• pp.31-38
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• 2022

위성용 TR모듈이 지상용 또는 항공용 TR모듈과 다른 점은 높은 레벨의 진동, 충격과 같은 발사환경과 우주방사능, 진공, 온도 변화와 같은 궤도환경 고려가 필요하다는 것이다. 따라서 지상용 또는 항공용 요구사양과는 다른 전기적, 구조적 조건을 요구한다. 이에 따라 서론에서는 발사환경, 궤도환경에 대해서 서술하고, 본문에서는 위성용 TR모듈에서 GaN의 활용과 요구되는 조건을 충족하기 위한 설계 과정을 기술한다. 특히, 부품선정부터 Derating&RF Budget 설계, 공정설계, 열해석까지 각각 단계에서 고려할 설계요소에 대해서 서술한다.

• Smart Structures and Systems
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• 제29권1호
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• pp.105-116
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• 2022

Stay cables play an essential role in cable-stayed bridges. Severe vibrations and/or harsh environment may result in cable failures. Therefore, an efficient structural health monitoring (SHM) solution for cable damage detection is necessary. This study proposes a data-driven method for immediately detecting cable damage from measured cable forces by recognizing pattern transition from the intact condition when damage occurs. In the proposed method, pattern recognition for cable damage detection is realized by time series classification (TSC) using a deep learning (DL) model, namely, the long short term memory fully convolutional network (LSTM-FCN). First, a TSC classifier is trained and validated using the cable forces (or cable force ratios) collected from intact stay cables, setting the segmented data series as input and the cable (or cable pair) ID as class labels. Subsequently, the classifier is tested using the data collected under possible damaged conditions. Finally, the cable or cable pair corresponding to the least classification accuracy is recommended as the most probable damaged cable or cable pair. A case study using measured cable forces from an in-service cable-stayed bridge shows that the cable with damage can be correctly identified using the proposed DL-TSC method. Compared with existing cable damage detection methods in the literature, the DL-TSC method requires minor data preprocessing and feature engineering and thus enables fast and convenient early detection in real applications.

• 융합경영연구
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• 제11권4호
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• pp.11-18
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• 2023

Purpose: The purpose of this study is to present policy implications by analyzing the residential environment in North Korea under the Kim Jong-un regime. Research design, data, and methodology: Residential environment analysis was reviewed by dividing it into physical, socio-cultural, economic, environmental, and policy aspects. Results: Pyongyang are considerably superior due to it being the residence of the country's leadership and middle class. Secondly, there is a concerning problem with the provision of substandard housing. Construction materials are in short supply, and unreasonable timelines often lead to uninhabitable houses, signaling a need for assistance in housing construction. Thirdly, there is a severe lack of essential residential infrastructure, such as reliable electricity and clean water supply, which significantly impacts the quality of life. Lastly, due to the country's economic hardships, basic housing rights are not guaranteed, leading to deplorable living conditions for many North Koreans. The report suggests that these issues should be addressed through international aid to guarantee the basic human rights of North Koreans. Conclusions: In North Korea, the poor living environment deteriorates the health and quality of life of citizens and adversely affects social and economic development. Therefore, international support and cooperation to improve the living environment of North Koreans is important.

• Journal of Plant Biotechnology
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• 제50권
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• pp.215-224
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• 2023

Disinfecting water containing pathogenic microbes is crucial to the food safety of fresh green agricultural products. The UV-activated peracetic acid (UV/PAA) treatment process is an efficient advanced oxidation process (AOP) and a versatile approach to disinfecting waterborne pathogens. However, its effects on plant growth remain largely unknown. This study found that low-dose UV/PAA treatment induced moderate oxidative stress but enhanced the innate immunity of Arabidopsis against Pseudomonas syringae pv. (Pst) DC3000. When applied as water sources, 5- and 10-ppm UV/PAA treatments slightly reduced biomass and root elongation in Arabidopsis seedlings grown under hydroponic conditions. Meanwhile, treatments of the same doses enhanced defense against Pst DC3000 infection in leaves. Accumulation of hydrogen peroxide and callose increased in UV/PAA-treated Arabidopsis samples, and during the post-infection period, UV/PAA-treated seedlings maintained vegetative growth, whereas untreated seedlings showed severe growth retardation. Regarding molecular aspects, priming-related defense marker genes were rapidly and markedly upregulated in UV/PAA-treated Arabidopsis samples. Conclusively, UV/PAA treatment is an efficient AOP for disinfecting water and protecting plants against secondary pathogenic attacks.

• 한국수소및신에너지학회논문집
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• 제25권3호
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• pp.227-233
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• 2014

Simulated waste-derived synthesis gas has been tested for hydrogen production through water-gas shift (WGS) reaction over supported Cu catalysts prepared by co-precipitation method. $CeO_2$, $ZrO_2$, MgO, and $Al_2O_3$ were employed as supports for WGS reaction in this study. $Cu-CeO_2$ catalyst exhibited excellent catalytic activity as well as 100% $CO_2$ selectivity for WGS in severe conditions ($GHSV=40,206h^{-1}$ and CO concentration = 38.0%). In addition, $Cu-CeO_2$ catalyst showed stable CO conversion for 20h without detectable catalyst deactivation. The high activity and stability of $Cu-CeO_2$ catalyst are correlated to its easier reducibility, high oxygen mobility/storage capacity of $CeO_2$.

• 환경정책연구
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• 제8권2호
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• pp.1-23
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• 2009

본 연구는 레이더 위성영상을 활용한 침수피해 지역 파악 및 그 완화방안의 도출을 위해 실제 침수지역을 대상으로 레이더 위성 영상의 침수피해에의 활용가능성을 살펴보았다. 이를 위하여 시계열 레이더 위성영상 자료를 활용하여 홍수에 취약한 침수 지역을 추출하고, 동일지역의 토지이용도에 대한 GIS 중첩분석을 통하여 토지이용 현황별 침수피해를 분석하였다. 사례 분석지역의 경우 침수피해가 심한 토지이용 형태는 농경지와 숲으로 나타났다. 본 연구는 레이더 위성영상을 활용하여 구축 가능한 침수피해 지도를 바탕으로 침수피해 완화를 위한 대응정책도 함께 논의하였다. 침수가 발생할 경우 긴급복구와 같은 위기대응적 접근도 중요하지만 무엇보다도 침수피해 지도와 같은 자료를 기반으로 위험한 지역에 건물의 입지를 제한하는 등 상습 침수피해 지역이 개발되지 않도록 예방적 차원에서의 토지 이용적 접근을 하여야 할 것이다. 본 연구에서 제안한 방안은 레이더 위성 영상의 환경 분야 활용과 침수피해를 최소화하는 방안의 일부이며, 레이더 위성영상은 대규모 홍수와 같은 재해문제 이외에도 다양한 환경 분야에 있어 활용 잠재력이 높으므로 향후 다양한 지역을 대상으로 레이더 위성영상을 여러 환경문제에 적용하는 연구가 계속되어야 할 것이다.

• 상하수도학회지
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• 제19권1호
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• pp.47-52
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• 2005

This study was conducted to evaluate the performance of submerged hollow fiber MF processes to treat secondary wastewater for water reuse. Specifically, membrane productivity and filtrate water quality were investigated under various operating conditions (i.e. flux, recovery, and backwash rate) at pilot-scale. Membrane fouling became more severe with increasing flux and recovery, suggesting that low flux operation (< 25 LMH) was desirable. At high flux operating(> 37.5 LMH), increasing backwash rate showed only limited success. The biofouling, quantified by PEPA and BFHPC, was also significant in wastewater reclamation, and biogrowth control by chlorine, were necessary to improve membrane productivity. Filtrate water qualities are in good compliance with water reuse regulations regardless of operating conditions (flux, recovery and backwash rate). Particle (e.g. turbidity) removal ranged from 89 to 98%, while only 11 to 21% of organics (e.g. NPDOC) were removed by MF membrane. Only small improvement in biostability (e.g. AOC) was achieved by MF system, and thus, without post disinfection, significant microorganisms might be present in the filtrate due to regrowth. Lastly, in order to further investigate pathogen removal, controlled microbial challenge tests were performed by monitoring Giardia, Cryptosporidium, bacteria and virus, and showed relatively good microbial removal.

• 농촌계획
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• 제11권4호
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• pp.47-57
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• 2005

The goal of this research is to evaluate landscape-ecological characteristics of watersheds in the Nakdong River Basin by using Geogaphic Information System (GIS) and landscape indices for integation of spatio-temporal informations and multivariate statistical techniques for quantitative analysis of forest landscape. Fragmentation index and change matrix techniques using factor analysis and grid overlay method were used to efficiently analyze and manage huge amount of information for ecological-environmental assessment (land-cover and forest landscape patterns). According to the results based on the pattern analysis of land-cover changes using the change detection matrix between 1980s and 1990s, addition on 750km$^2$ became urbanized areas. The altered 442.04km$^2$ was agricultural areas which is relatively easy for shifting of land-use, and 205.1km$^2$ of forests became urbanized areas, and average elevation and slope of the whole altered areas were 75m and 4$^{\circ}$. On the other hand, 120km$^2$ of urban areas were changed into other areas (i.e., agricultural areas and green space), and fortunately, certain amount of naturalness had been recovered. But still those agricultural areas and fallow areas, which were previously urban areas, had high potential of re-development for urbanization due to their local conditions. According to the structural analysis of forest landscape using the landscape indices, the forest fragmentation of watersheds along the main stream of the Nakdong River was more severe than my other watersheds. Furthermore, the Nakdong-sangju and Nakdong-miryang watersheds had unstable forest structures as well as least amount of forest quantity. Thus, these areas need significant amount of forest through a new forest management policy considering local environmental conditions.

• Journal of Microbiology and Biotechnology
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• 제28권11호
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• pp.1850-1858
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• 2018

Glucosamine (GlcN) is widely used in the nutraceutical and pharmaceutical industries. Currently, GlcN is mainly produced by traditional multistep chemical synthesis and acid hydrolysis, which can cause severe environmental pollution, require a long prodution period but a lower yield. The aim of this work was to develop a whole-cell biocatalytic process for the environment-friendly synthesis of glucosamine (GlcN) from N-acetylglucosamine (GlcNAc). We constructed a recombinant Escherichia coli and Bacillus subtilis strains as efficient whole-cell biocatalysts via expression of diacetylchitobiose deacetylase ($Dac_{ph}$) from Pyrococcus furiosus. Although both strains were biocatalytically active, the performance of B. subtilis was better. To enhance GlcN production, optimal reaction conditions were found: B. subtilis whole-cell biocatalyst 18.6 g/l, temperature $40^{\circ}C$, pH 7.5, GlcNAc concentration 50 g/l and reaction time 3 h. Under the above conditions, the maximal titer of GlcN was 35.3 g/l, the molar conversion ratio was 86.8% in 3-L bioreactor. This paper shows an efficient biotransformation process for the biotechnological production of GlcN in B. subtilis that is more environmentally friendly than the traditional multistep chemical synthesis approach. The biocatalytic process described here has the advantage of less environmental pollution and thus has great potential for large-scale production of GlcN in an environment-friendly manner.

• 한국환경농학회지
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• 제25권2호
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• pp.174-179
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• 2006

Chinese cabbage, Braccica campestris has long been consumed as a staple food for Koreans in various forms of fresh, salted, and fermented Kimchi. Cultivation of the crop under greenhouse has become a general practices to fulfill its off-seasonal consumer's demand. However, agricultural practices of the crop have always accompanied with heavy applications of pesticides caused by severe outbreaks of diseases and pose under warm and humid circumferences. Since dissipation patterns of pesticide residues in/on the crop under greenhouse conditions ate quite different from those in the open-air, changes of diazinon, O,O-diethyl O-2-isopropyl-6-methylpyrimidin-4-yl phosphornthioate, in/on the Chinese cabbage applied by foliar spraying under greenhouse were studied. Diazinon 34% EC was applied with dilution of recommended and double dose to the crop. The shoots of crop were harvested immediately after this application and at regular intervals over a 10-day. After sample preparations, the diazinon residue was analyzed using gas chromatography equipped with electron capture detector (GC/ECD). Initially deposited amount of the chemical in/on the crop right after applications with recommended and double doses were 8.3 and 15.2 mg/kg, respectively. The residue levels after 10 days of application were 0.03 and 0.09 mg/kg with 1.3 and 1.5 days of half-life in/on the crop, respectively. In consequent 10 days of pre-harvest interval (PHI) for diazinon EC formulation in/on Chinese cabbage under greenhouse condition was fulfill maximum residue level set by Korea Food and Drug Administration (KFDA, 0.1 mg/kg).