• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.2 no.2
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• pp.53-68
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• 1997

Lake Shihwa, artificially constructed since 1988, shows a typical two-layered system depending on strong haline density stratification. Sill of the water gate at 6 m depth greatly restricts physical mixing with outer seawater and circulation in the lake, and contributes to the enhancement of anoxic environment in the deeper layer. With this enclosed physical environment, Lake Shihwa receives enormous amounts of organics, ammonia, and other pollutants from the neighboring municipal and industrial complexes through six major streams, thus developing biogeochemical differentiation of anoxic to suboxic environment in the high saline bottom water and highly eutrophicated brackish surface water. This study investigated vertical structures, biogeochemical behaviors and processes of various organic and inorganic compounds around oxic-anoxic interface. Nitrite and nitrate rapidly decreased below the pycnocline where about $1{\times}10^8$ tons of hypoxic bottom water exist. In this bottom layer, ammonium ranged from 75 to 360 ${\mu}M$ mainly resulting from deamination of dissolved organic nitrogen and ammonification of precipitated organic particles. Despite large amounts of surface water discharge and dilution by outer seawater inflow about $3{\times}10^8$ tons from April to August, 1996, bottom layer did not show any improvement of water quality and maintained highly reduced environment. The main reason seems to be imbalance between ineffectiveness of dilution due to shallow depth and large surface area, overloaded POC influx from the eutrophicated surface biological activity, and poor replenishment of oxygen in this artificial lake system. Therefore, as long as current salinity dependent two-layered system maintains with its physical limitations, any improvement of water quality cannot be foreseen in Lake Shihwa.

• Journal of the Korean Geographical Society
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• v.29 no.3
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• pp.318-339
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• 1994

U.S. had given large amount of cotton to Korea as food aid program since 1945. This cotton aid had negative impact on cotton culture in Korean agriculture. Korean government used counterparts funds (sale proceeds of food aid) not for investment to agriculture sector, but for military budgets. And food aid on program type had influenced general economic policies, which neglected agricultural sector too. Anti-agricultural policy which was helped by U.S. food aid, had caused cotton cultivator an economic loss. So this economic loss had made many farmers abandon cotton culture. But in our times, cotton is cultivated for the purpose of domestic consumption in a few rural villages. The purposes of this study are 1) to analyze the process of spatial reduction of cotton culture since 1945 in regional contexts in Korea, and 2) to identify the function and meaning of cotton culture which does not pay off in agricultural region. Materials for acreage of cotton culture are acquired through the agricultural statistical year book(1952-1989) and census. To clarify the meanings of cotton culture, field survey are conducted in a rural village which is identified as only one where cotton was cultivated in 1993. In these contexts, this study has come to the following conclusions. In the period of under the rule of Japanese Imperialism (1910-1945), G. arboreum, species of cotton which was traditionally cultivated since 1364, had been driven out. And G. hirustun species, which is suitable for the production of highly qualified textile, has been hierarchically diffused by policy. In these period, regional structure of Korean agriculture was reorganized for the provision with food to Japan. Crops leading this dependent spatial structure were rice and cotton. So agricultural region, specialized with cotton, were distributed in the hinterland of the area which is specialized with rice. U.S. cotton aid to Korea began in 1947. U.S. took an interest in agricultural export because of her domestic surplus of cotton. Cotton aid is one mechanism by which U.S government developed agricultural market in recipient countries, Specially in the exchange rates, up-valuation of won to the U.S. dollars made domestic cotton more expensive than cotton imported, Production cost of domestic cotton is higher than Government's purchasing price of cotton which was also more expensive than price of cotton imported. Korean farmer could not help abandoning the cultivation of cotton, and this gave rise to spatial reduction of cotton culture. Spatially, cotton culture was abandoned in early stage of reduction in regions where stand at a disadvantage climatically, and in next stage in regions where other up-land crops which paid off in urban market, eg, fruits, could be cultivated. In the stage of extinction, cotton was cultivated only in area where G. hirustun species was originated in Korean peninsula. This region is not only suitable climatically for cotton culture, but is far away from urban market. Use of cotton produced is not for spinning, but for fillings of comforter. The main purpose of cotton culture in rural village is not for cotton yields, but for increase of production of seasame, which is grown together with cotton as mixed crops. Cotton product are used for domestic consumption and sold out to gin house. Though cotton culture is not paid off, farmer wanted to cultivate continuously for the cultural purpose, and they wanted the cotton culture promotion policy with the goverment subsidy.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.75-82
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• 2011

Five different composition UV-cured poly(urethane acrylate-co-acrylic acid) (PU-co-AA) films have been prepared by reacting isophorone diisocyanate(IPDI), polycaprolactone triol(PCLT), 2-hydroxyethyl acrylate(HEA), and different weight ratio trimethylolpropane triacrylate(TMPTA) and acrylic acid(AA) as diluents, and characterized using a Fourier transform infrared spectroscopy(FT-IR). The adhesion properties onto the stainless steel, morphology, mechanical hardness, and electrical property of UV-cured PU-co-AA films were investigated as a function of acrylic acid(AA) content. All the PU-co-AA films are structure-less and the molecular ordering and packing density decreased with increasing content of AA due to the flexible structure and -COOH side chains in AA. The crosscut test showed that PU-co-AA films without AA and with low content of AA showed 0% adhesion(0B) and the adhesion of PU-co-AA films in the range of 40-50% AA increased dramatically as the content of AA increases. The pull-off measurements showed that the adhesion force of PU-co-AA films to stainless steel substrate varied from 6 to 31 kgf /$cm^2$ and increased linearly with increasing AA content. The mechanical hardness also decreased as the content of AA increases. This may come from relatively linear and flexible structure in AA and low crystallinity in PU-co-AA films with higher content of AA. The higher AA-containing PU-co-AA films showed higher dielectric constant due to the increase of polarization by introducing AA monomer. In conclusion, the physical properties of UV-cured PU-co-AA films are strongly dependent upon the content of AA and the incorporation of AA in polyurethane acrylate is very useful way to increase the adhesion strength of UV-curable polymers on the stainless steel substrate.

• The Korean Journal of Nuclear Medicine Technology
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• v.12 no.1
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• pp.44-48
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• 2008

Purpose: In FDG-PET/CT of breast cancer, a sensitivity was 80~96% and a specificity was 75~95% commonly. It was valuable to identify a cancer in early stage been difficult in Mammography. Most of the PET/CT scans have been examined on supine position, so, the image of breast has been acquired by reconstructed whole body scan image. However, using prone position with a compensator, a shape of breast was reassembly shown to be real by gravity. Therefore, the purpose of this study was to evaluate diagnostic value of prone position in FDG PET-CT of breast cancer. Materials and Methods: 30 female patients with doubtful or positive breast cancer were examined. The PET-CT whole body scan was acquired at 60 minutes after $^{18}F$-FDG injection on Supine position. Then, regional breast spot scan was progressed on prone position using a compensator. Each image was evaluated by physicians blinded to patient's data, and statistical analysis did through SUVs measured in PET-CT images. Results: In 27 of 30 patients, prone position was shown accurate discrimination and diagnostic value, but in another 3 patients had a lesion 1cm below, PET-CT couldn't detect it, unlike MRI. Consequently, prone position distinguished a lesion better than Supine position, because of low degree of metamorphosis by gravity. The SUVs analysis of each position was significant (p value=0.004). Conclusion: In PET-CT of breast cancer, prone position could detect micrometastasis as well as primary lesion, better than supine position. Therefore, this study proposes that any technical change considered morphological feature like prone position can offer adequate and useful diagnostic information, together with complementary quantitative analysis.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.428-433
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• 2013

Heterogenous samples of locust bean gum (galactomannan) were prepared into homogeneous substances. Locust bean gum was fractioned using ammonium sulfate (14.11-23.08%, w/w). The intrinsic viscosity was obtained by extrapolating reduced viscosity versus concentration by using an Ubbelohde viscometer. The ranges of intrinsic viscosity for fractions that not included protein (F3-F6) and fractions that included protein (F1-F2) were 9.89-8.10 and 8.44-4.59, respectively. Values for Huggins' coefficient (k'), which depends on physical interactions, were 0.46-0.78. Increasing ammonium sulfate concentration was associated with a weak trend towards lower molecular weight and intrinsic viscosity by size-exclusion chromatography (SEC): $M_w$ ranged from 674 to 617 kg/mol and [${\eta}$] from 9.80 to 8.10 dL/g between F3 and F6. The evaluations of those fractions by using SEC and the Ubbelohde viscometer produced very similar values, as predicted. We verified the application of a gradient of ammonium sulfate to precipitate locust bean gum into fractions of different molecular size and show structural variations.

• KDI Journal of Economic Policy
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• v.31 no.1
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• pp.169-206
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• 2009

This study stems from a question, "How should we understand the pattern of the Korean economy after the 1990s?" Among various analytic methods applicable, this study chooses a Structural Vector Autoregression (SVAR) with long-run restrictions, identifies diverse impacts that gave rise to the current status of the Korean economy, and differentiates relative contributions of those impacts. To that end, SVAR is applied to four economic models; Blanchard and Quah (1989)'s 2-variable model, its 3-variable extensions, and the two other New Keynesian type linear models modified from Stock and Watson (2002). Especially, the latter two models are devised to reflect the recent transitions in the determination of foreign exchange rate (from a fixed rate regime to a flexible rate one) as well as the monetary policy rule (from aggregate targeting to inflation targeting). When organizing the assumed results in the form of impulse response and forecasting error variance decomposition, two common denominators are found as follows. First, changes in the rate of economic growth are mainly attributable to the impact on productivity, and such trend has grown strong since the 2000s, which indicates that Korea's economic growth since the 2000s has been closely associated with its potential growth rate. Second, the magnitude or consistency of impact responses tends to have subsided since the 2000s. Given Korea's high dependence on trade, it is possible that low interest rates, low inflation, steady growth, and the economic emergence of China as a world player have helped secure capital and demand for export and import, which therefore might reduced the impact of each sector on overall economic status. Despite the fact that a diverse mixture of models and impacts has been used for analysis, always two common findings are observed in the result. Therefore, it can be concluded that the decreased rate of economic growth of Korea since 2000 appears to be on the same track as the decrease in Korea's potential growth rate. The contents of this paper are constructed as follows: The second section observes the recent trend of the economic development of Korea and related Korean articles, which might help in clearly defining the scope and analytic methodology of this study. The third section provides an analysis model to be used in this study, which is Structural VAR as mentioned above. Variables used, estimation equations, and identification conditions of impacts are explained. The fourth section reports estimation results derived by the previously introduced model, and the fifth section concludes.

• Korean journal of communication and information
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• v.73
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• pp.56-91
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• 2015

This study examined changes in the independent production environment in the perspectives from flexible specialization of labor and media routines since January 2011, when comprehensive programming television channels (JTBC, MBN, Channel A, TV Chosun) emerged in Korea. In-depth interviews were conducted with thirteen individuals, including producers from independent production companies, broadcast writers, and individuals involved with these TV channels. The interview results indicated that a flexible specialization production system had been established by the comprehensive programming channels. This means that they were heavily dependent on independent producers, except in relations to their own news programs. Moreover, it was identified that the production of diverse programs could be difficult due to absurd contract practices such as those related to TV ratings and performance systems. Second, these channels have implemented some positive changes such as the payment of higher production costs and an incentive system, compared to terrestrial TV stations. However, the incentive system also helps to aggravate internal competition in the channel and also instigate contract competitions among independent companies, which can eventually result in the channels for holding exclusive rights to certain content and, hence, unfair business practices. Third, as a result of the newspaper and broadcast cross-owenership system of the comprehensive programming channels, hierarchical independent production practices can be established under the influence of newspaper proprietors and executives or managers who have previously worked for newspapers. Lastly, as a result of interviews with independent producers and individuals involved with the TV channels concerning the awareness of comprehensive programming channels, it could not be ascertained whether it is difficult to produce programs dealing with diverse items and genres, because programming autonomy has been distorted by capital or the advertisement market. In this circumstance, it is not surprising that some comprehensive programming channels mentioned that they prioritize profit and performance in programming. In conclusion, it is absolutely imperative that complementary and legal measures be implemented institutionally in order to redress the existing systematic dysfunctional routines in the independent productions of the comprehensive programming TV channels in Korea.

• Journal of the Korean Magnetics Society
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• v.7 no.5
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• pp.265-273
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• 1997

The MR ratios and the exchange biasing field and interlayer coupling field were investigated in $Ni_{91}Fe_{19}/Co_{90}Fe_{10}/Cu/Co_{90}Fe_{10}/NiO$ spin-valve sandwiches grown on antiferromagnetic NiO films as a function of the NiO thickness, the thickness of Cu and pinning layer $Co_{90}Fe_{10}$. The spin-valve sandwiches were deposited on the Corning glass 7059 by means of the 3-gun dc and 1-gun rf magnetron sputtering at a 5 mtorrpartial Ar pressure and room temperature. The deposition field was 50 Oe. The MR curve was measured by the four-terminal method with applied magnetic soft bilayer [NiFe/CoFe] (90$\AA$) decreased dramatically to less than 10 Oe when the NiFe/CoFe bilayer used an NiFe bilayer thicker that 20$\AA$. So NiFe layer improved the softmagnetic properties in the NiFe/CoFe bilayer. The GMR ratio and the magnetic field sensitivity of the spin-valve film $Ni_{91}Fe_{19}(40{\AA})/Co_{90}Fe_{10}(50{\AA}) /Cu(30{\AA})/Co_{90}Fe_{10}(35{\AA})/NiO(800{\AA})$ was 6.3% and about 0.5 (%/Oe), respectively. The MR ratio had 5.3% below an annealing temperature of 20$0^{\circ}C$ which slowly decreased to 3% above 30$0^{\circ}C$. The large blocking temperature of the spin-valve film was taken (as being) due to the good stability of the NiO films. Thus, the spin-valve films with a free NiFe/CoFe layer clearly had a high large GMR output and showed a effective magnetic field sensitivity for a suitable spin-valve head material.

• Korean Journal of Food Science and Technology
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• v.30 no.4
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• pp.976-982
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• 1998

The effects of the glycoprotein (PAG) isolated from Pteridium aquilinum on the immune function was examined in mice. PAG was intraperitoneally administered into BALB/C mice for 14 days and the antibody forming ability to hen egg lysozyme (HEL) and the blastogenic responses of splenocytes were measured. PAG treatment significantly increased antibody formation to HEL in a dose-dependent manner. Blatogenesis of splenocytes in response to lipopolysaccharide (LPS, B-cell specific mitogen) or phytohemagglutinin (PHA, T-cell specific mitogen) was also increased after treatment with PAG, indicating that the PAG increases both humoral and cellular immunities. To examine whether the immune function of PAG was via a direct effect on the lymphocytes, splenocytes were isolated from BALB/C mice, exposed to various concentrations of PAG in vitro and the blastogenic responses were measured. In vitro exposure to PAG significantly increased blastogenesis of splenocytes to LPS up to $500{\;}{\mu}g/kg$, whereas the blastogenic response to PHA was not altered by PAG treatment. To identify the fraction responsible for the increase in the immune function, the effect of periodate digest, pronase digest or purified polysaccharide on the antibody production to HEL was examined. Crude protein fraction of PAG significantly increased the antibody formation to HEL. On the other hand, both crude and purified polysaccharide fractions did not have any effects on the antibody production ability. These data indicated that 1) PAG increased both humoral and cellular immune functions, 2) the increase in humoral immunity was probably via a direct action of PAG on lymphocytes and 3) the protein portion of PAG was responsible for the increase in humoral immunity.

• Journal of Korean Society of Forest Science
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• v.90 no.1
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• pp.43-54
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• 2001

Genetic differentiation of populations is resulted from the environmental and the genetic effects, and the interactions between them. Whereas, the major factors influencing to the genetic differentiation within populations are the gene flow induced by seed or pollen dispersial, the microsite heterogeneity, and the density-dependent distribution of individuals. For the purpose of studying spatial genetic structure and the distribution pattern of Korean pines(Pinus koraiensis), we set up one $100{\times}100m$ plot at a Korean pine stand in Quercus mongolica community on Mt. Jumbong in Korea. To estimate the coefficient of spatial autocorrelation as Moran's index and an analogue, simple block distance, isozyme markers were analyzed in 325 Korean pines. For 11 polymorphic loci observed in 9 enzyme systems, the average percentage of polymorphic loci, the observed and expected heterozygocity were 72.2% 0.200, and 0.251, respectively. It was revealed the excess of homozygotes was observed in the plot, which suggests that here may be more number of consanguineous trees than expected. On the basis of isozyme genotypes observed in this study, 325 trees were classified into 147 groups in which the maximum number of trees for one group was 34. From the distance class of 24-32m, the genetic heterogeneity began to increase. The variation of simple block distance against the growth performance by tree height and diameter also showed the same trend at 24~32m class. According to high fixation index(F=0.204), the spatial genetic structure within a stand, the analysis of the growth performance, and the distribution patterns of identical genotypes, we inferred that the genetic structure of a Korean pine stand in Mt. Jumbong has been maintained rather density-dependent mechanism than the gene flow, such as the pollen dispersial or the heavy input of seeds following the forest gaps. The genetic patchy size was determined between 24~32m, which suggests that the selection of individuals for the ex situ conservation of Korean pine in Mt. Jumbong may be desirable to be made with the spatial distance over 37 meters between trees.