• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.1
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• pp.19-26
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• 2019

The objective of this study was to analyze bacteriological and chemical hazards in minimally processed commercial fish products, including Hwangtae (freeze-dried pollock), dried anchovy, fermented anchovy sauce, and salted and dried yellow croaker. Escherichia coli counts from all samples were below the regulation limits of the Korean Ministry of Food and Drug Safety Standards on Quality of Seafood and Seafood Products (Food Code). However, the food poisoning bacterium Staphylococcus aureus was detected at levels above $1.0{\times}10^2$ colony forming units (CFU)/g in Hwangtae, dried anchovy, and salted and dried yellow croaker, which are commonly ingested without heating and pose bacteriological hazards. The detection of S. aureus, an organism indicative of poor personal hygiene, which can be introduced by employees and multiply during distribution, indicates the necessity of improving the sanitary control of minimally processed commercial fish products. Histamine was not detected from dried anchovy or salted and dried yellow croaker, but was detected at some of the highest levels in fermented anchovy sauces. This result suggests that efforts to reduce the amount of histamine in fermented anchovy sauces are required.

• Tribology and Lubricants
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• v.38 no.5
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• pp.185-190
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• 2022

Among the operating limits of a heat pipe, the capillary limit is significantly affected by the characteristics of the wick, which is determined by the capillary performance. The major parameters for determining capillary performance are the maximum capillary pressure and the spreading characteristics that can be expected through the wick. A well-designed wick structure improves capillary performance and helps improve the stability of the heat pipe by enhancing the capillary limit. The capillary performance can be improved by forming a porous microstructure on the surface of the wick structure through surface modification techniques. In this study, a microstructure is formed on the surface of the wick by using a surface modification method (i.e., an electrochemical etching process). In the experiment, specimens are prepared using stainless-steel screen mesh wicks with various fabrication conditions. In addition, the spreading and capillary rise performances are observed with low-surface-tension fluid to quantify the capillary performance. In the experiments, the capillary performance, such as spreading characteristics, maximum capillary pressure, and capillary rise rate, improves in the specimens with microstructures formed through surface modification compared with the specimens without microstructures on the surface. The improved capillary performance can have a positive effect on the capillary limit of the heat pipe. It is believed that the surface microstructures can enhance the operational stability of heat pipes.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.42.2-42.2
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• 2020

We report on multi-wavelength observations of AA Ori, a Young Stellar Object in Orion-A star-forming region. AA Ori is known to have a pre-transitional disk based on infrared observations including Spitzer/IRS data. We construct its broadband spectral energy distribution (SED) by not only taking data in the optical and IR region but also including Herschel/PACS, JCMT/SCUBA, and SMA observational data. We use the Monte Carlo radiative transfer code (RADMC-3D) to reconstruct the SED with a viscous accretion disk model initialized by a radially continuous disk and finally having an inner and outer dusty disk separated by a dust-depleted radial gap. By comparing the model SEDs with different configurations of disk parameters, we discuss the limits to find a single solution of model parameters to fit the data. We suggest that some models with a modified inner disk surface density gradient and some degree of dust depletion in the inner disk can explain the AA Ori's SED, from which we infer that the inner disk of AA Ori has evolved. We present that model configurations of a pre-transitional disk with a large gap extended to 60-80 AU in a settled dusty disk of a few hundred AU size with a high inclination angle (~60°) also create model SEDs close to the observed one. To distinguish whether the disk has a just-opened narrow gap or a large gap, with an altered surface density of the inner disk extended to 10 AU, we suggest a further investigation of AA Ori with high angular resolution observations.

• Journal of Microbiology and Biotechnology
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• v.33 no.8
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• pp.1101-1110
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• 2023

Streptococcus mutans is the primary causative agent of caries, which is one of the most common human diseases. Thus, rapid and early detection of cariogenic bacteria is critical for its prevention. This study investigated the combination of loop-mediated isothermal amplification (LAMP) and microfluid technology to quantitatively detect S. mutans. A low-cost, rapid microfluidic chip using LAMP technology was developed to amplify and detect bacteria at 2.2-2.2 × 10⁶ colony-forming units (CFU)/ml and its detection limits were compared to those of standard polymerase chain reaction. A visualization system was established to quantitatively determine the experimental results, and a functional relationship between the bacterial concentration and quantitative results was established. The detection limit of S. mutans using this microfluidic chip was 2.2 CFU/ml, which was lower than that of the standard approach. After quantification, the experimental results showed a good linear relationship with the concentration of S. mutans, thereby confirming the effectiveness and accuracy of the custom-made integrated LAMP microfluidic system for the detection of S. mutans. The microfluidic system described herein may represent a promising simple detection method for the specific and rapid testing of individuals at risk of caries.

• Journal of Korea Water Resources Association
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• v.36 no.3 s.134
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• pp.507-520
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• 2003

A V-shaped riffle is an artificial hydraulic structure haying two wings from the streamside with a narrow opening in between. It is usually made of crushed stones or large boulders. It limits channel width and accelerates the flow through the constricted section causing a local scour just downstream. The V-shaped riffle provides with a unique aquatic habitat by forming a pool and sandbars around the pool edge, increasing local morphologic, hydraulic and sedimentological diversity. This study investigates experimentally the scour characteristics of the V-shaped riffle in the sandbed stream and proposes a predictive equation for the scour. Total 45 cases of experiments were conducted to examine the effect of hydraulic factors and configuration of V-shaped riffle on the geometry of scour holes. From the comparison of the experimental results of this study with the predictive equation of spur dike by Breusers and Raudkivi(1991), it is found that their predictive equation of spur dike underestimates the maximum scour depth downstream of the V-shaped riffle. h new predictive equation for the maximum scour depth was developed using the non-dimensional hydraulic and geometrical variables. The parameters used in the proposed equations were determined using the experimental data. The analysis reveals that the scour depth is dependent dominantly on the Froude number at the opening of the V-shaped riffle, while the angle of riffle and the opening width also affect the scour depth. The proposed equation for the scour of V-shaped riffle well agrees with the experimental data. It can be used for estimating the scour of the V-shaped riffle in sandbed streams.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.126-142
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• 2020

Background: Most of the Pinus densiflora forests, occupying the largest area, have been restored in South Korea since the 1970s. As young pioneer forests, the succession process is under way. Since the forests are distributed nationwide and are vulnerable to disturbances, the process may differ depending on the geography and/or site conditions. Therefore, we reviewed the direction, the seral communities, and the late-successional species of progressive and disturbance-driven succession nationwide in the cool-temperate zone through meta-analysis and empirical observations. Main text: As a result of a meta-analysis of the direct succession and vertical structure, we found that the P. densiflora forest is in a directionally progressive succession, changing to the broadleaved forest after forming a mixed forest with its overwhelming successor, Quercus species (particularly Q. mongolica and Q. serrata). In dry stands in a relative sense, the Quercus species was favored occupying over 80% of the abundance of the succeeding species. Therefore, in dry stands, it is presumed that Quercus-dominated stage would last for a long time due to the current dominance and long life span, and eventually, it settles as Quercus-broadleaved forest with a site change. Contrary to this, it is presumed that in mesic stands where Quercus species do not occur or have low abundance, the late-successional broadleaved species settle early to form a co-dominant forest with multiple species. Due to geographical limits, the species composition of the two late-successional forests is different. Disturbances such as insect pests and fire retrogressed vulnerable P. densiflora forest for a while. However, it was mostly restored to the Quercus forest and is expected to be incorporated in the pathway of the dry stand. Conclusions: We revealed the succession process of P. densiflora forests according to geography and moisture and found that stand moisture had a decisive effect on the species and abundance of the successor. Although the P. densiflora forest is undergoing structural changes, the forest is still young; so within a few decades, physiognomy is not likely to change. Therefore, the decrease in the forest area may be due to other causes such as disturbances and forest conversion rather than due to succession.

• Journal of the Economic Geographical Society of Korea
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• v.9 no.3
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• pp.318-340
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• 2006

In the last decade, there has been a widespread interest in knowledge production activities as a new engine of endogeneous growth. In the knowledge-based economy, there has been a growing importance of the patent as the index of knowledge production. Much literature suggests that knowledge production activities tend to be spatially concentrated and formed the clusters in the advanced economies. The purpose of this paper is to analyze spatial-temporal patterns of knowledge production activities in Korea based on a data set of patents from 1981-2000. This paper uses spatial statistical methods and GIS to explore the spatial dimensions of knowledge production activities in Korea. Through this research, it was found that knowledge production activities were unevenly distributed. The knowledge production activity measured by patent counts is highly concentrated in a limited number of cities. The top 10 cities accounted for 68.5% of the total number of patents in the period of 1981-2000, suggesting the existence of a strong concentration of knowledge production activities in Korea. The locations of knowledge production activities by themselves represented a strong spatial autocorrelation. The concentration of knowledge production activities in Korea is spatially correlated to the concentration of adjacent neighboring cities. The location of knowledge production activities is not free from a spatial context and spillover of knowledge production activities are heavily bounded within geographic limits, forming a spatial cluster. There appear some quite a large spatial cluster around the seoul metropolitan area.

• Korean journal of communication and information
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• v.51
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• pp.117-135
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• 2010

The regulation of media concentration which is provided in the German Interstate Treaty on Broadcasting (RStV) is part of the rules forming the "positive broadcasting order" required by German Constitutional Law. This control ensures that the diversity of viewpoints can be articulated to the public. Broadcasting must operate independently from the state and from particular social groups if it is to be a genuine service to the public. One risk of economic competition in the media is a tendency towards the concentration of business enterprises. Moreover, economic competition is no guarantee for journalistic diversity. The aim of balanced diversity in the broadcasting sector can only be pursued by creating conditions under which different voices obtain the chance to be heard in an equitable manner. Within the framework of the meaning of section 26, it shall be assumed that there is a predominant impact on public opinion if the programs attributable to one company reach an annual audience share of 30 percent. The same shall apply if the company reaches an audience share of 25 percent and holds a dominant position in a related media-market or an overall assessment of its activities in television. The restriction of audience shares has limits such as that the audience shares of news programs and education and entertainment programs are pooled. Therefore, there is a vagueness about the productivity of different program branches.

• Trans-
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• v.1
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• pp.1-19
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• 2016

Arts have changed continuously reflecting the times with the political atmosphere and social systems. As political, economic, and social big changes have occurred since World War II, antihistorical tendencies rejecting modernism in the early 20th century have come to appear in culture and arts as well. With these social changes, radical, avant-garde and artistic tendencies with strong experimental spirits, which rejected modernism took place especially in American dancing world. Trends of improvised elements and experimental trials were dominated discovering expressions of new movements in intentions and expressions of works. The purpose of this study is to investigate the effects on choreographic forms of modern dance until today by exploring choreographic characteristics of this postmodernism. To examine post-modernist inclinations in works, Trisha Brown who led American post-modern dance stressed dance for expressions of movements in themselves and pure movements by actively accepting into dance works American social flows which played a major role in postmodernism starting from 1960s. American modern dancers considered body in itself as important one and any emotional expressions and individual sensitivity is excluded as their physical expressions are factual, realistic, and due to their movements. They imprinted dance as valuable art by recreating ordinary behaviors into dance, using space excellently and forming experimental dance shapes. Therefore, it can be said that through analyzing brown's works, we proposed a new direction getting out of limits of arts and provided a direction of essential dance alt to movements of modern dance and choreographic shapes.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.271-272
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• 2012

Bulk Metallic Glasses (BMGs or amorphous alloy) exhibit high strength and good corrosion resistance. Applications of thin films and micro parts of BMGs have been used a lot since its inception in the research of BMGs. However, Application and fabrication of BMGs are limited to make structural materials. Thin films of BMGs which is sputtered on the surface of structural materials by sputtering process is used to improve limits about application of BMGs. In order to investigate the difference of properties between designed alloys and thin films, we identified that thin films deposited on the surface that have the characteristic of the amorphous films and the composition of designed alloys. Zr-Cu (Cu=30, 35, 38, 40, 50 at.%) and Zr-Cu-Al (Al=10 at.% fixed, Cu=26, 30, 34, 38 at.%) alloys were fabricated with Zr (99.7% purity), Cu (99.997% purity), and Al (99.99% purity) as melting 5 times by arc melting method before rods 2mm in diameter was manufactured. In order to analyze GFA (Glass Forming Ability), rods were observed by Optical Microscopy and SEM and $T_g$, $T_x$, ($T_x$ is crystallization temperature and $T_g$ is the glass transition temperature) and Tm were measured by DTA and DSC. Powder was manufactured by Gas Atomizer and target was sintered using powder in large supercooled liquid region ($=T_x-T_g$) by SPS(Spark Plasma Sintering). Amorphous foil was prepared by RSP process with 5 gram alloy button. The composition of the foil and sputtered thin film was analyzed by EDS and EPMA. In the result of DSC curve, binary alloys ($Zr_{62}Cu_{38}$, $Zr_{60}Cu_{40}$, $Zr_{50}Cu_{50}$) and ternary alloys ($Zr_{64}Al_{10}Cu_{26}$, $Zr_{56}Al_{10}Cu_{34}$, $Zr_{52}Al_{10}Cu_{38}$) have $T_g$ except for $Zr_{70}Cu_{30}$ and $Zr_{60}Al_{10}Cu_{30}$. The compositions with $T_g$ made into powders. Figure shows XRD data of thin film showed similar hollow peak.