• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.324-325
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• 2014

Quantum wells infrared photodetectors (QWIPs) have been used to detect infrared radiations through the principle based on the localized stated in quantum wells (QWs) [1]. The mature III-V compound semiconductor technology used to fabricate these devices results in much lower costs, larger array sizes, higher pixel operability, and better uniformity than those achievable with competing technologies such as HgCdTe. Especially, GaAs/AlGaAs QWIPs have been extensively used for large focal plane arrays (FPAs) of infrared imaging system. However, the research efforts for increasing sensitivity and operating temperature of the QWIPs still have pursued. The modification of heterostructures [2] and the various fabrications for preventing polarization selection rule [3] were suggested. In order to enhance optical performances of the QWIPs, double barrier quantum well (DBQW) structures will be introduced as the absorption layers for the suggested QWIPs. The DBWQ structure is an adequate solution for photodetectors working in the mid-wavelength infrared (MWIR) region and broadens the responsivity spectrum [4]. In this study, InGaAs/GaAs/AlGaAs double barrier quantum well infrared photodetectors (DB-QWIPs) are successfully fabricated and characterized. The heterostructures of the InGaAs/GaAs/AlGaAs DB-QWIPs are grown by molecular beam epitaxy (MBE) system. Photoluminescence (PL) spectroscopy is used to examine the heterostructures of the InGaAs/GaAs/AlGaAs DB-QWIP. The mesa-type DB-QWIPs (Area : $2mm{\times}2mm$) are fabricated by conventional optical lithography and wet etching process and Ni/Ge/Au ohmic contacts were evaporated onto the top and bottom layers. The dark current are measured at different temperatures and the temperature and applied bias dependence of the intersubband photocurrents are studied by using Fourier transform infrared spectrometer (FTIR) system equipped with cryostat. The photovoltaic behavior of the DB-QWIPs can be observed up to 120 K due to the generated built-in electric field caused from the asymmetric heterostructures of the DB-QWIPs. The fabricated DB-QWIPs exhibit spectral photoresponses at wavelengths range from 3 to $7{\mu}m$. Grating structure formed on the window surface of the DB-QWIP will induce the enhancement of optical responses.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.2
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• pp.116-122
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• 1982

In three diverse wheat and one barley cultivars were used to examine the relation of the spikelet and floret differentiation to fertility and an winter wheat Norin 61 was used to examine the spikelet size gradients in the mature ear in relation to their grain development. The greatest number of grains and florets per spikelet, and the heaviest grains occurred in the low-mid part of the ear. Within the spikelets, the 2nd grain from the base was heavier than the I st or the 3rd one. In this region, the fertility of the 1 st floret was 97%, the 2nd 93%, the 3rd 88%, and 4th floret was 15%. The fertility of the wheat and barley was closely related to spikelet and floret differentiation. Barley spikelets was fertile as their differentiation stage was X that is 25 days before heading. Wheat florets were fertile as their differentiation stage was X that is 15-20 days before heading. But, they were sterile or reduced in fertility if they were not reached to the stage X.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.29 no.4
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• pp.438-449
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• 1996

Development of alimentary tract and nutrient absorption in embryo of the viviparous teleost surfperch, Ditrema temmincki were investigated with histochemical methods. Just after hatching mouth of the embryo was opened, and the end part of alimentary tract was opened in TL 4.0 mm. Mucosal folds in the alimentary tract appeared at posterior region from TL 5.0 mm. In TL 30.0 mm, the alimentary tract of the embryo could be distinguished into pharynx, esophagus, anterior intestine, mid intestine, posterior intestine, rectum and anus. From over TL 50.0 mm, the internal histological patterns of the alimentary tract showed similar structures as seen in the adult. The mucous cells in the pharynx were positively reacted to PAS in TL 7.0 mm. PAS positive goblet cell appeared in the intestine from 25.0 mm, from TL 30.0 mm in the rectum, from TL 40.0 mm in the anus and from 50.0 mm in the esophagus. Yolky materials were absorbed completely in TL 6.0 mm. PAS positive polysaccharide absorptive cells began to appear at the posterior parts of the intestine in TL 7.0 mm and appeared in TL 13.0 mm at the rectum, in TL 15.0 mm at the anterior intestine and in TL 40.0 mm at the anterior part of anus. During the gestation period, nutrient absorptive type of the embryo within the maternal body is a placental analogues type of metrotrophy.

• Journal of the Korean Association of Geographic Information Studies
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• v.16 no.3
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• pp.12-24
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• 2013

Eradication of endemic malaria was declared in mid 1980's in Korea, but the number of malaria cases has been oscillating for the past 10 years since the reemergence of the disease in early 1990's. The occurrence of malaria has been concentrated near the demilitarized zone(DMZ), and the regional characteristics of the disease are evident. Considering the spatial variations of malaria incidence across the high-risk areas, the hotspot of the disease, it seems that the occurrence of the disease is influenced by the natural and human environment in the region. Malaria is an infectious disease that is transmitted to humans by the bites of vector-mosquitoes carrying malaria parasites, and it depends on specific climatic and sociodemographic factors. Malaria transmission is highly climate-sensitive, and temperature is the most important component. In addition, human contacts with vector-mosquitoes and the distance between human residence and mosquito habitats are crucial conditions determining malaria incidence rates. The present study aimed to test a hypothesis that the spatial characteristics of malaria incidence depended on local climatic conditions, relative proportions of mosquito habitats, and the distance between mosquito habitats and human residence using meteorological and satellite-based land cover data.

• Journal of The Korean Society of Grassland and Forage Science
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• v.35 no.1
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• pp.43-49
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• 2015

This experiment was conducted to evaluate the agronomic characteristics and forage productivity of Italian ryegrass cultivars in Yecheon, Kyeongbuk from 2011 to 2013. The experimental design was a randomized complete block design (RCBD) with three replications. Italian ryegrass cultivars were seeded on Sep. 26 in 2011 and Sep. 25 in 2012. The Italian ryegrass cultivars were harvested on the heading date of the variety. The cold-resistance of domestic cultivars was stronger than other foreign varieties. Among early-maturing cultivars, the dry matter (DM) yield of the "Kowinearly" was 10,031 kg/ha, which was significantly higher than that of other cultivars (p<0.05). In medium-maturing cultivars, the DM yield of the "Kowinmaster" and "Tam 90" were 10,484 and 8,191 kg/ha, respectively. Of the two, the former's DM yield was higher than the latter's (p<0.05). Among late-maturing cultivars, the DM yield of "Hwasan 104" was 10,641 kg/ha, which was similar to that of "Hwasan 101" and significantly higher than the other late-maturing cultivars (p<0.05). According to the results obtained from this study, an early-maturing variety with cold-tolerance and high productivity is required for the paddy field cultivation of an Italian ryegrass cultivar after rice harvest in the mid-northern region of Korea. A medium- or late-maturing variety is more advantageous for the field cultivation of the maximum quantity that is possible. In conclusion, to select which variety/ies to grow, the climate of the growing area, weather conditions, and the cropping system must all be considered.

• The Journal of the Acoustical Society of Korea
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• v.39 no.5
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• pp.379-389
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• 2020

In this study, the flow and noise performances of high-speed fan motor unit for cordless vacuum cleaner is improved by optimizing the impeller which drives the suction air through flow passage of the cordless vacuum cleaner. Firstly, the unsteady incompressible Reynolds averaged Navier-Stokes (RANS) equations are solved to investigate the flow through the fan motor unit using the computational fluid dynamics techniques. Based on flow field results, the Ffowcs-Williams and Hawkings (FW-H) integral equation is used to predict flow noise radiated from the impeller. Predicted results are compared to the measured ones, which confirms the validity of the numerical method used. It is found that the strong vortex is formed around the mid-chord region of the main blades where the blade curvature change rapidly. Given that vortex acts as a loss for flow and a noise source for noise, impeller blade is redesigned to suppress the identified vortex. The response surface method using two factors is employed to determine the optimum inlet and outlet sweep angles for maximum flow rate and minimum noise. Further analysis of finally selected design confirms the improved flow and noise performance.

• Journal of Veterinary Clinics
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• v.22 no.2
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• pp.148-152
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• 2005

An intact female, 5-year-old, Pekingese, weighing 3.5kg with a history of a palpated abdominal mass was referred to Veterinary Medical Teaching Hospital, Seoul National University. In laboratory examination, there were no remarkable abnormalities. Radiographic findings included a left mid-abdominal mass with ill-defined margin, serosal detail loss of peritoneal space, non-uniform opacity of retroperitoneal space, and a radiopaque cystic calculus. On abdominal ultrasonography, a heterogeneous parenchymal mass with irregular contour in the left renal region was found. Computed tomographic findings showed a tumor embolus within the caudal vena cava and an invasion into mesentery, small bowel loops, spleen and pancreas around the large left renal mass. Unilateral nephroureterectomy was performed. Histopathologic examination of the resected mass confirmed the diagnosis of renal cell carcinoma. The dog died one day after surgery. Although ultrasonography could give diagnostic information about mass characteristics, computed tomography (CT) can provide key imaging features of mass characteristics.

• Journal of the Korean Geographical Society
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• v.47 no.1
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• pp.13-36
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• 2012

This paper is to reconsider comprehensively and systematically major issues on transnational immigrants, increased rapidly since the beginning of the 1990s, and their impacts on socio-spatial changes in S. Korea. Foreign immigrants who have moved on the contexts of unevenness of globalization and advancces in transport & telecommunication technology on the global level and of economic development and shortage of cheap and unskilled workers have been distributed unevenly, concentrating on the Capital region and local areas with industrial complexes. Foreign workers seems to have some negative influences on regional economies in the long-term, though positive in the short-term. Domestic people seem to have an ambivalent attitude which accepts necessity of multi-culture, while simultaneously continues to be self-confident on ethnic homogeneity. The Korean government has launched multicultural policies for foreign immigrants by the mid-2000, but still continues some policies with assimilationism and differential exclusionism, marginalizing them socio-spatially, while lacking local government's policy and programmes. In conclusion, in order to resolve these problems and to transfer multicultural societal space of Korea, a geography of transnational migration which promotes especially discourse and policy with authentic multiculturalism, extending roles of local government, and ensuring glocal citizenships.

• Journal of The Korean Society of Grassland and Forage Science
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• v.32 no.3
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• pp.293-300
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• 2012

This experiment was carried out to compare the agronomic characteristics, forage yield and quality of sorghum ${\times}$ sudangrass hybrid at two locations (Sungju and Cheonan) in 2009. The experiment was a randomized complete block design with three replications. The eight recommended hybrids used in this experiment were 'Sordan 79', 'SX17', 'Honey chew', 'Honey grazer', 'G7', 'Jumbo', 'Green star' and 'GT56' hybrids. The heading of four hybrids were headed at both region, Sungju and Cheonan. There are no big differences in general agronomic characteristics among hybrids, but brix scale of heading and BMR (brown mid rib) types were higher than those of other hybrids. Dry matter (DM) and plant height of heading type hybrids were higher than those of headless types. The fresh, DM and TDN (total digestible nutrients) yields of heading type hybrids were also higher than those of headless types, and BMR types were lower than others. The crude protein and crude ash contents of headless hybrids were higher than those of heading hybrids, while its non-fiber carbohydrate (NFC) content showed the opposite results. The acid detergent fiber (ADF) and NFC contents of BMR types were lower than others. The results of this experiment indicates that heading hybrids were more higher than headless hybrids in the agronomics and forage yield of sorghum ${\times}$ sudangrass. However heading types were lower headless types in quality of sorghum ${\times}$ sudangrass. And BMR hybrids were also high quality of sorghum ${\times}$ sudangrass hybrid because of higher brix content and lower ADF content among tested hybrids.

• Journal of the Korean Geographical Society
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• v.42 no.6
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• pp.863-878
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• 2007

The time-spatial distribution of Scrub typhus and its relationship with environmental ecology, such as climate, and habitat change are analyzed in respect of the geography of disease. Scrub typhus was firstly reported in 1951, and reemerged in 1986 mainly in southwestern Korea. later it has sharply increased and spreaded out toward whole country in 1998 and 2004, except mid-eastern mountainous region. Hwasung City is the typical example of sudden upsurge of Scrub typhus. High incidence of Scrub typhus patients might due to elevated temperature and decreased precipitation during the summer, as well as milder autumn. Sharp increase of Scrub typhus patients at rural area since 1980's might also be the result of the rapid changes of land use pattern, which eventually have contributed for the active development of dense vegetation and propagation of chigger mites around cultivated land.