• Korean Journal of Agricultural and Forest Meteorology
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• v.16 no.2
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• pp.93-102
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• 2014

This quantitative research aims to examine the connectivity of forest networks in seven metropolitan cities of South Korea using a graph-theoretical approach. We first estimated an overall network connectivity at multi-scales (i.e., dispersal distances), ranging from 100 m to 20 km, and quantified the contribution of small forest patches (less than 10 ha) to the overall network connectivity by comparing networks according to the presence and absence of small ones. As a result, the cities were divided into two groups depending on the network connectivity; one group of cities with high connectivity such as Daegu, Daejeon, and Ulsan and the other group of cities with low connectivity including Gwangju, Busan, Seoul, and Incheon. The result showed that small forest patches, especially in the cities with low connectivity, played a key role as stepping stones that connect large forested patches, thereby contributing to maintaining connectivity. This study also suggests that large and well-connected forest areas may be the key factor to preserve the connectivity in the cities with high connectivity, while the cites with low connectivity are in need of some complementary strategies. Through the study, we suggest that the creation of new forest patches in the areas where a gap in connectivity presents is needed in order to improve connectivity; and that the conservation of the existing small forest patches is essential in order to maintain the current connectivity level.

• Journal of Preventive Medicine and Public Health
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• v.41 no.3
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• pp.181-185
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• 2008

Objectives : This study was performed to evaluate the reproducibility of a questionnaire concerned with reproductive history and to ascertain which characteristics of the subjects (age, the visit-revisit intervals, education and chronic disease) are associated with good reliability in the Korean Multi-Center Cancer Cohort (KMCC) study. Materials and Methods: A total of 19,688 participants were enrolled between 1993 and 2004. Among them, we selected 386 participants who were aged 40 or more and who re-visited within 8 years after the first visit. Reliability was measured by the percent agreement according to error range for the continuous variables and the percent agreement and kappa statistics for the categorical variables. Results : The pregnancy histories were reliable (kappa=0.67) and the reasons for being menopausal among the postmenopausal women were also reliable (kappa=0.92). The percent agreement of the breast-feeding history was high (96.1%), although the kappa statistic was low. For the continuous variables, when the error range of one variable was considered to be reliable, the percent agreement of the age at menarche and the age at the first full term pregnancy was good (69.4% and 83.6%), whereas that of the age at menopause was low (51.5%). The factors associated with high reliability were a younger age, the presence of chronic disease and a short visit-revisit time interval. Conclusions : The agreements for parity, the reasons for menopause, and the breastfeeding history in the reproductive history questionnaire used in the KMCC were relatively good. The questionnaire for the menarche age and the menopausal age might have lower reliability due to the difference between Korean age and American age. To obtain reliable information, more attention should be given to the items in questionnaire-based surveys, and especially for surveying old-aged women.

• Journal of the Korean association of regional geographers
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• v.23 no.1
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• pp.1-22
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• 2017

This paper is to consider conceptually a formation of food-networks and border-crossing of transnational marriage migrant households on the basis of actor-network theory, and to analyze empirical data on the issues collected by interview with marriage migrant women living around Daegu, S.Korea. Some research results can be argued as follows: First, food can be seen, not as a single material object, but as a multiple and hybrid network of human and nonhuman (material and institutional) actors, in which activities of food cooking and eating are regulated by and (re)construct social relations and placeness of households. Secondly, food-networks in marriage migrant households implement relationships of micro-power (and attachment) in the process of its (re)formation, and hence the food-network, it can be argued, is a field of power in which conflicts and compromising around food cooking and eating are intersecting each others. Thirdly, food-networks in marriage migrant households in both their origin country and in the Korean home are not only affected by macro natural and social environments but also by micro placeness of the households, both of which constitute the food-networks and operate in relations with other actors in the netwroks. Finally, food-networks in marriage migrant households reflect multiple and multi-scalar spatial mobility and placeness of transnational food culture, through which they express topologically 'fluid space' and 'absent presence', in which marriage migrant women can (or cannot) conduct social and cultural border-crossing.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.588-588
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• 2013

Nanoscale noble-metals have attracted enormous attention from researchers in various fields of study because of their unusual optical properties as well as novel chemical properties. They have possible uses in diverse applications such as devices, transistors, optoelectronics, information storages, and energy converters. It is well-known that nanoparticles of noble-metals such as silver and gold show strong absorption bands in the visible region due to their surface-plasmon oscillation modes of conductive electrons. Silver nanocubes stand out from various types of Silver nanostructures (e.g., spheres, rods, bars, belts, and wires) due to their superior performance in a range of applications involvinglocalized surface plasmon resonance, surface-enhanced Raman scattering, and biosensing. In addition, extensive efforts have been devoted to the investigation of Gold-based nanocomposites to achieve high catalytic performances and utilization efficiencies. Furthermore, as the catalytic reactivity of Silver nanostructures depends highly on their morphology, hollow Gold nanoparticles having void interiors may offer additional catalytic advantages due to their increased surface areas. Especially, hollow nanospheres possess structurally tunable features such as shell thickness, interior cavity size, and chemical composition, leading to relatively high surface areas, low densities, and reduced costs compared with their solid counterparts. Thus, hollow-structured noblemetal nanoparticles can be applied to nanometer-sized chemical reactors, efficient catalysts, energy-storage media, and small containers to encapsulate multi-functional active materials. Silver nanocubes dispersed in water have been transformed into Ag@Au nanoboxes, which show highly enhanced catalytic properties, by adding $HAuCl_4$. By using this concept, $SiO_2$-coated Ag@Au nanoboxes have been synthesized via galvanic replacement of $SiO_2$-coated Ag nanocubes. They have lower catalytic ability but more stability than Ag@Au nanoboxes do. Thus, they could be recycled. $SiO_2$-coated Ag@Au nanoboxes have been found to catalyze the degradation of 4-nitrophenol efficiently in the presence of $NaBH_4$. By changing the amount of the added noble metal salt to control the molar ratio Au to Ag, we could tune the catalytic properties of the nanostructures in the reduction of the dyes. The catalytic ability of $SiO_2$-coated Ag@Au nanoboxes has been found to be much more efficient than $SiO_2$-coated Ag nanocubes. Catalytic performances were affected noteworthily by the metals, sizes, and shapes of noble-metal nanostructures.

• Tuberculosis and Respiratory Diseases
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• v.62 no.2
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• pp.119-124
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• 2007

Sarcoidosis is a multi-system granulomatous disorder of an unknown etiology and affects individuals worldwide. It is characterized pathologically by the presence of non-caseating granulomas in more than one involved organ. However, pleural involvement of sarcoidosis is rare and there are no reported cases in Korea. Traditionally, sarcoidosis has often been treated with systemic corticosteroids or cytotoxic agents. In particular, chylothorax with sarcoidosis is usually treated with corticosteroid for approximately 3~6 months, followed by repeated therapeutic thoracentesis, talc pleurodesis, dietary treatment, or thoracic duct ligation where needed. We encountered a 46 years old female patient presenting with cough, dyspnea and both hilar lymphadenopathy (stage I) on chest radiograph. The patient was diagnosed with a non-caseating granuloma, sarcoidosis by a mediastinoscopic biopsy. For one month, she had suffered from dyspnea due to right side pleural effusion, which was clearly identified as a chylothorax on thoracentesis. Corticosteroid therapy with dietary adjustment was ineffective. She was treated successfully with a subcutaneous injection of octreotide for 3 weeks and oral corticosteroid. We report a case of successful and rapid treatment of chylothorax associated with sarcoidosis using octreotide and oral corticosteroid.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5C
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• pp.527-539
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• 2009

In this paper, we propose an asynchonous ICI (Inter-Cell Interference) mitigation techniques for 3GPP LTE MIMO-OFDMA down-link receiver. An increasing in symbol timing misalignments may occur relative to sychronous network as the result of BS (Base Station) timing differences. Such symbol synchronization errors that exceed the guard interval or the cyclic prefix duration may result in MAI (Multiple Access Interference) for other carriers. In particular, at the cell boundary, this MAI becomes a critical factor, leading to degraded channel throughput and severe asynchronous ICI. Hence, many researchers have investigated the interference mitigation method in the presence of asynchronous ICI and it appears that the knowledge of the SCM (Spatial Covariance Matrix) of the asynchronous ICI plus background noise is an important issue. Generally, it is assumed that the SCM estimated by using training symbols. However, it is difficult to measure the interference statistics for a long time and training symbol is also not appropriate for MIMO-OFDMA system such as LTE. Therefore, a noise reduction method is required to improve the estimation accuracy. Although the conventional time-domain low-pass type weighting method can be effective for noise reduction, it causes significant estimation error due to the spectral leakage in practical OFDM system. Therefore, we propose a time-domain sinc type weighing method which can not only reduce the noise effectively minimizing estimation error caused by the spectral leakage but also implement frequency-domain moving average filter easily. By using computer simulation, we show that the proposed method can provide up to 3dB SIR gain compared with the conventional method.

• Interdisciplinary Bio Central
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• v.1 no.2
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• pp.7.1-7.7
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• 2009

"To be, or not to be?" This question is not only Hamlet's agony but also the dilemma of mitochondria in a cancer cell. Cancer cells have a high glycolysis rate even in the presence of oxygen. This feature of cancer cells is known as the Warburg effect, named for the first scientist to observe it, Otto Warburg, who assumed that because of mitochondrial malfunction, cancer cells had to depend on anaerobic glycolysis to generate ATP. It was demonstrated, however, that cancer cells with intact mitochondria also showed evidence of the Warburg effect. Thus, an alternative explanation was proposed: the Warburg effect helps cancer cells harness additional ATP to meet the high energy demand required for their extraordinary growth while providing a basic building block of metabolites for their proliferation. A third view suggests that the Warburg effect is a defense mechanism, protecting cancer cells from the higher than usual oxidative environment in which they survive. Interestingly, the latter view does not conflict with the high-energy production view, as increased glucose metabolism enables cancer cells to produce larger amounts of both antioxidants to fight oxidative stress and ATP and metabolites for growth. The combination of these two different hypotheses may explain the Warburg effect, but critical questions at the mechanistic level remain to be explored. Cancer shows complex and multi-faceted behaviors. Previously, there has been no overall plan or systematic approach to integrate and interpret the complex signaling in cancer cells. A new paradigm of collaboration and a well-designed systemic approach will supply answers to fill the gaps in current cancer knowledge and will accelerate the discovery of the connections behind the Warburg mystery. An integrated understanding of cancer complexity and tumorigenesis is necessary to expand the frontiers of cancer cell biology.

• Geophysics and Geophysical Exploration
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• v.5 no.4
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• pp.299-308
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• 2002

We have derived an analytical expression for the sensitivity of the frequency domain small-loop electromagnetic (EM) surveys over a two-layer earth in order to estimate the depth of investigation with an instrument having the source-receiver separation of about 2 m. We analyzed the sensitivities to the lower layer normalized by those to the upper half-space and estimated the depth of investigation from the sensitivity analyses and the mutual impedance ratio. The computational results showed that the in-phase components of the sensitivity to the lower layer dominates those to the upper layer when the thickness of the upper layer is less than 20 m, while the quadrature components are not sensitive to the lower layer over the entire frequency range. Hence we confirmed that the accurate measurement of the in-phase component is essential to increase the depth of investigation in the multi-frequency small-loop EM survey. When conductive basement of 10 ohm-m underlies the upper layer of 100 ohm-m, an accurate measurement of the in-phase components ensures the depth of the investigation more than 10 m even accounting a noise effect, from which we conclude that the small-loop EM survey is quite effective in imaging the conductive plume down to a considerable depth. On the other hand, in the presence of the resistive basement of 1,000 ohm-m, the depth of investigation may not exceed 5 m considering the instrumental accuracy, which implies that the application of the small-loop EM survey is not recommended over the resistive environment other than detecting the buried conductor.

• Journal of the HCI Society of Korea
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• v.10 no.2
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• pp.13-19
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• 2015

Display technology has recently made enormous progress. In particular, display companies are competing each other to develop flexible display. Curved display, as a precursor of flexible display, are now used for smart phones and TVs. Curved monitors have been just introduced in the market, and are used for office work or entertainment. The aim of the current study was to investigate whether the curvature of a 42" multi-monitor affects postural control when it is used for entertainment purpose. The current study used two curvature levels (flat and 600mm). Ten college students [mean(SD) age = 20.9 (1.5)] with at least 20/25 visual acuity, and without color blindness and musculoskeletal disorders participated in this study. In a typical VDT environment, each participant played a car racing video game using a steering wheel and pedals for 30 minutes at each curvature level. During the video game, a pressure mat on the seat pan measured the participant's COP (Center of Pressure), and from which four measures (Mean Velocity, Median Power Frequency, Root-Mean-Square Distance, and 95% Confidence Ellipse Area) were derived. A larger AP (Anterior-Posterior) RMS distance was observed in the flat condition, indicating more forward-backward upper body movements. It can be partly due to more variability in visual distance across display, and hence longer ocular accommodation time in the case of the flat display. In addition, a different level of presence or attention between two curvature conditions can lead to such a difference. Any potential effect of such a behavioral change by display curvature on musculoskeletal disorders should be further investigated.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.9
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• pp.623-629
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• 2012

The objective was to evaluate the quality of harvested rainwater of the roofing materials used and the presence of lichens/mosses on the roofing surface. This experiment was studied in the field where five pilot structures with different roofing materials (i.e., wooden shingle tiles, wooden shingle tiles (including mosses), concrete tiles, clay tiles [Gi-Wa] and slate tiles) were installed. As a result, the clay tiles [Gi-Wa] was found to be the most suitable for rainwater harvesting applications. It was due to the disinfection from ultraviolet light and high temperature according to characteristic of roofing materials. Comparison with quality of rainwater on that wooden shingle tiles with and without including mosses, which may affect the concentration of and wooden shingle tiles including mosses, mosses may affect concentration of TOC, nitrate, and sulfate. Additionally, the average concentration of asbestos was determined to be measured at $0.002/cm^3$ for the slate tiles. The value satisfied with it met the Ministry of Environment's Multi-use facility standard and Ministry of Labor's Office standard ($0.01/cm^3$).