• 한국환경복원기술학회지
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• 제22권2호
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• pp.49-57
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• 2019

The street trees increase the liveability of cities by reducing stormwater runoff, improving air quality, storing carbon, providing shade, and ameliorating the urban heat-island effect. In this study, the health status of street trees in Suwon was evaluated, and the factors affecting the growth of the trees were also derived. In order to evaluate the growth and health of street trees, field survey was carried out on a total of 125 trees in 25 sections of the Deogyeong-daero where is through the city. During the field survey, the following items were examined: Street trees health status (i.e. species, height, DBH (diameter at breast height), planting types, vigor, etc.), soil factors (i.e. soil temperature, humidity, pH, hardness, etc.), and environmental factors (i.e. landuse, road width, etc.). As the results of field survey, the main species of the street trees was Zelkova serrata, which was healthy in most of the sections. The factors such as planting types, soil temperatures, tree root cover, road extension, distance from the road were derived to affect the growth and health of street trees, and the differences were significant. The results of this study were derived the following conclusions for vigorous street trees: First, it is important to install and maintain the protection facilities like tree root cover for the growth of trees. Second, it is necessary to discuss how to plant multiple trees in narrow spaces like a street green space. Third, it is important to provide appropriate soil conditions continuously for growth of threes. Finally, it should be utilized as a mitigation measure of urban heat island effects.

• 한국환경농학회지
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• 제31권4호
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• pp.313-317
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• 2012

감귤은 접목을 통해 일반적으로 번식을 한다. 국내에서 온주밀감의 주요 대목으로 이용되는 탱자(Poncirus trifoliata)는 다른 대목에 비해 왜성이고 내한성이 강한 특징을 갖고 있다. 부지화((Citrus unshiu ${\times}$ C. sinensis) C. reticulata) 감귤에서도 이러한 탱자대목의 우수한 특성 때문에 주요 대목으로 탱자를 이용하고 있고 이 대목에서 발생된 뿌리는 당연히 탱자뿌리로 인식하고 있다. 그러나 몇 년 전부터 부지화 감귤나무에서 착화량 감소가 농가들 사이에서 문제시 되어왔는데 이 원인에 대해서는 강전정, 과다착과, 생육기간의 온도에 의해 발생되었다고 추측하였다. 이러한 착화량 감소가 부지화의 자근에 의해 발생이 되었다고 생각하는 연구자는 거의 없었다. 그래서 본 연구는 국내에서 부지화 감귤 나무에서 자근의 존재여부를 밝히기 위하여 수행되었다. 본 연구를 위해 부지화 재배 농가들 중 착화가 불량한 과원당 나무 3~4주를 무작위로 선정하여 조사를 수행하였다. 뿌리는 각 조사나무에서 표토 5cm 부위에서 잔뿌리를 채취하여 DNA를 추출한 뒤 품종 판별에 이용하였다. 부지화 자근 판별에는 F2/R15, F4/R15, F5/R15의 3가지 프라이머 세트를 이용하였다. DNA 분석결과, 착화가 불량한 부지화 20주 중 14주가 자근이 발생된 것으로, 나머지 6주는 다른 요인에 의해 착화가 불량한 것으로 밝혀졌는데 이러한 결과는 국내에서 처음 보고되는 결과이다. 부지화 자근이 발생된 뿌리는 탱자보다 표면이 어두웠으며 직경도 더 컸다. 자근발생여부를 확인하기 위해 F2/R15, F4/R15, F5/R15 프라이머 세트를 이용하였을 때 부지화 자근과 탱자뿌리 판별이 가능하였고 자근이 실제 재배현장에서 발생되고 있음을 알 수 있었다. 자근이 발생된 나무는 정상대목의 나무에 비해 착과량이 유의하게 감소하였다. 금번 결과를 통해서 봤을 때 부지화 재배과원에서 자근의 발생과 그 영향에 대한 조사와 연구가 시급히 필요할 것으로 생각되며 그에 따른 재배법 개발도 뒤따라야 할 것으로 판단되었다.

• International Journal of Ocean System Engineering
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• 제2권3호
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• pp.160-169
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• 2012

Flux Cored Arc Welding (FCAW) is a common practice to join thick plates such as the structural members of large scale offshore structures and very large container ships. The objective of this study was to investigate the mechanical properties and variability of the fatigue crack initiation life in the flux cored arc welded API 2W Gr.50 steel joints typically applied to offshore structures with a focus on the effect of the materials in fatigue crack growth life from the notch root of a compact tension specimen. Offshore structural steel (API 2W Gr.50) plates (60-mm thick) were used to fabricate multi-path flux core arc welded butt welded joints to clearly consider fatigue fractures at the weld zone from the notch. Fatigue tests were performed under a constant amplitude cyclic loading of R = 0.4. The mean fatigue crack initiation life of the HAZ specimen was the highest among the base metal (BM), weld metal (WM), and heat affected zone (HAZ). In addition, the coefficient of variation was the highest in the WMl specimen. The variability of the short fatigue crack growth rates from the notch tips in the WM and HAZ specimens was higher than in BM.

• 한국압력기기공학회 논문집
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• 제10권1호
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• pp.82-89
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• 2014

In this study, the metallurgical analysis and mechanical property measurement have been performed to investigate the effect of long-term thermal aging on the microstructural evolution in the fusion boundary region between weld metal and low alloy steel in dissimilar metal welds. A representative dissimilar weld mock-up made of Alloy 690-Alloy 152-A533 Gr. B was fabricated and aged at $450^{\circ}C$ for 2,750 hours. The microstructural characterization was conducted mainly near in a weld root region by using optical microscopy, scanning electron microscopy, transmission electron microscopy. And the mechanical properties were measured with Vickers microhardness test and nanoindentation method. A steep gradient was shown in the chemical composition profile across the interface between A533 Gr. B and Alloy 152. Type-II boundaries were found in weld side of DMW and the hardness was the highest at the narrow zone between Type-II boundary and fusion boundary.

• 한국조경학회지
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• 제26권2호
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• pp.207-218
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• 1998

A site survey in two apartment complexes and a nursery experiment were carried out in this study to provide basic data of the long-pending growth characteristics of major landscaping trees, such as Picea abies, Pinus parviflora, Metasequoia glyptostroboides, Magnolia denudata, Acer buergerianum and Acer palmatum. According to the main results, the survival rates were very low, reflected by the average survival rate of the four species was 95% at the nursery site. And, it was presumed that the site conditions of two apartment complexes for tree growth were very inferior to those of the nursery site, taking into consideration that the increment percents of growth factors of the tree species at the nursery site were relatively higher than those of the apartment complexes. The distribution patterns of the current growth factors of trees showed a normal distribution. The regression equation of breast diameter on diameter at root collar showed especially high predictability. And, it was thought that the most critical limiting environmental factors on tree growth at the apartment complexes were found to be alkaline pH caused by excessive Ca, high percent base saturation, insufficiency of available moisture content, bad drainage due to inferior soil texture, high soil hardness, lack of organic matter and shortage of cation exchange capacity in soil.

• 농업과학연구
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• 제42권3호
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• pp.183-189
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• 2015

Plant root penetration through soil profile is restricted by compacted layer such as plow pan under conventional tillage. For detecting the compact layer, we made a graduated T-shape probe and measured compared between the depths with rapid change in feeling hardness of hand penetration using T-shape probe and with a rapid increase of penetrometer cone index. On upland crops, including red pepper, corn, soybean and cucumber, plow pan depth ranged from 10 cm to 25 cm depth. The effective rooting depth (ER) had significant correlation with the plow pan depth (PP) except soils with the shallow ground water and/or poorly drained soil. The regression equation was ER = 0.9*PP ($R^2=0.54^{**}$, N = 14) with the applicative PP range of 10-25 cm.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 D
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• pp.1555-1557
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• 1998

In order to investigate the core material for over-head transmission line with non-magnetic and high strength nitrogen steel, microstructure and several basic properties of Fe-Mn-Cr-Ni-N steel have been studied. It is necessary that core material have a $\gamma$ phase to have a non-magnetic characteristics. To acquire a $\gamma$ phase, Mn, Ni and C are added as a alloying element. It was found that Fe-25Mn-16Cr-1Ni-N alloy have a stable $\gamma$ phase. The precipitate from this alloy system was $(Cr, Fe)_7C_3$. High Mn and N steel satisfies Sievert's relation that solubility of nitrogen increases with the square root of partial pressure of gas in metal-gas system and the hardness have proportional relation with nitrogen concentration.

• 한국식생활문화학회지
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• 제28권1호
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• pp.107-113
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• 2013

Yacon (Smallanthussonchifolius) is a root crop that contains high amounts of fructo-oligosaccharides (FOS). FOS has a sweet taste, is low in calories, and is known to promote intestinal tract health. In this study, various yacon concentrates were substituted for sugar in white pan bread to obtain healthy benefits from the use of FOS. The quality characteristic changes during storage of the white pan breadswith 0, 25, 50, 75 and 100% of added yacon concentrates instead of sugar were investigated. During storage, the water contents and water activities of the breads made with high amounts of yacon concentrates changed less than in those made with only sugar. The hardness and chewiness of the breads made with high amounts of yacon concentrates had lower values than those made with only sugar. Thus, bread made with yacon concentrates might exhibit increased moisture retention and decreased aging velocity. The substitution of yacon concentrates for sugar in pan bread improved the bread quality.

• 한국조경학회지
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• 제31권6호
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• pp.85-94
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• 2004

This study was carried out to analyze physicochemical properties according to the soil height and to the six types of sites that were used as planting ground in the reclaimed land from the sea, Gwangyang Bay. The physicochemical properties of the soil types were tested by t-test(p<0.01, 0.05), at each of the 6 planting ground sites(p<0.01, 0.05), and at each height(p<0.01) of the planting grounds. These areas were tested by ANOVA and were significantly different. Improved soil was better than reclaimed soil from the sea for Zelkova growth because the improved soil contained lower amounts of pH, ECe, N $a^{+}$, $Ca^{++}$, $Mg^{++}$ SAR. Due to freedom from variables such as salt content in the underground as well as the physical and chemical disturbance of the soil, favorable planting ground for tree growth was recorded at the higher grounds than at the lower ones. Soil detriment to the tree growth in the studied sites included elements such as soil hardness, and the distribution of sodium in the tree root systems. The planting grounds for the favorable growth of landscape trees were determined in the following order: the grounds of mounding> the coved ground of improved soil, and the filled ground of improved soil.l.l.l.

• 대한금속재료학회지
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• 제56권11호
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• pp.796-804
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• 2018

The Charpy impact toughness of the heat affected zone (HAZ) of electro gas welded 390 MPa yield strength grade steel, manufactured by a thermo mechanically controlled process, was investigated. The effects of added Nb on the toughness of the steel and the factors influencing scatter in toughness are discussed in the present work. It was observed that adding Nb to the steel led to the deterioration of HAZ toughness. The presence of soluble Nb in the HAZ increased its hardenability and resulted in a larger amount of low toughness bainitic microstructure. Microstructural observations in the notch root area revealed the significant role of different microstructures in the area. In the presence of a larger amount of bainitic microstructures, the HAZ exhibited a lower Charpy toughness with a larger scatter in toughness. A softened zone with a lower hardness than the base metal was formed in the HAZ. However, theoretical analysis revealed that the presence of the zone might not be a problem in a real welded joint because of the plastic restraint effect enforced by surrounding materials.