• Korean Journal of Social Welfare Studies
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• v.44 no.3
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• pp.177-206
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• 2013

The Korean government has implemented the senior employment policy as a direct job creation policy since 2004. A realistic discussion of policy alternatives and orientation for this has been given little attention even though senior employment policy has been carried out for the last 10 years and it will be expanded next year. This study tries to examine active labor market policy especially focusing on direct job creation programs and policies for the disadvantaged low-income elderly in OECD countries, and then it suggests some developmental alternatives for senior employment policy based on the study's results. The main results from this analysis are summarized in two points. Firstly, except pension policies, employment policy for older workers in the OECD countries is highly proportional to the tackling of objective factors reducing the demand for older workers (wage subsidies, reduced social security contribution rate etc). And the strategies of improving employability have not been relatively important and direct job creation policy has been marginal. Secondly, employment support policies for the low-income elderly can be divided into three types: support for the low-income elderly, alleviating early retirement and support for full employment according to the criteria which are determined by policy objectives and the social economic index. Korea's employment support policies belong to the type of direct job creation among them. This seems to be due to the fact that the rate of elderly poverty is extremely high and an income security system has not been developed in Korea. However, the policy objective is still uncertain. Therefore, this policy needs to set up clear objectives and establish a proper system for the achievement of its goals. If we focus on the strength of its employment characteristics, we need to modify the policy's plan in the perspective of labor market policy. But if we intend to keep both of the current objectives, it is better for this policy to be divided into two parts: social participation and income supplements. Or it also may be a solution to transform the system into an employment service, a training system which supports participants to move into unsubsidized jobs such as SCSEP in the U. S.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.1-2
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• 2011

Hybrid rockets have lately attracted attention as a strong candidate of small, low cost, safe and reliable launch vehicles. A significant topic is that the first commercially sponsored space ship, SpaceShipOne vehicle chose a hybrid rocket. The main factors for the choice were safety of operation, system cost, quick turnaround, and thrust termination. In Japan, five universities including Hokkaido University and three private companies organized "Hybrid Rocket Research Group" from 1998 to 2002. Their main purpose was to downsize the cost and scale of rocket experiments. In 2002, UNISEC (University Space Engineering Consortium) and HASTIC (Hokkaido Aerospace Science and Technology Incubation Center) took over the educational and R&D rocket activities respectively and the research group dissolved. In 2008, JAXA/ISAS and eleven universities formed "Hybrid Rocket Research Working Group" as a subcommittee of the Steering Committee for Space Engineering in ISAS. Their goal is to demonstrate technical feasibility of lowcost and high frequency launches of nano/micro satellites into sun-synchronous orbits. Hybrid rockets use a combination of solid and liquid propellants. Usually the fuel is in a solid phase. A serious problem of hybrid rockets is the low regression rate of the solid fuel. In single port hybrids the low regression rate below 1 mm/s causes large L/D exceeding a hundred and small fuel loading ratio falling below 0.3. Multi-port hybrids are a typical solution to solve this problem. However, this solution is not the mainstream in Japan. Another approach is to use high regression rate fuels. For example, a fuel regression rate of 4 mm/s decreases L/D to around 10 and increases the loading ratio to around 0.75. Liquefying fuels such as paraffins are strong candidates for high regression fuels and subject of active research in Japan too. Nakagawa et al. in Tokai University employed EVA (Ethylene Vinyl Acetate) to modify viscosity of paraffin based fuels and investigated the effect of viscosity on regression rates. Wada et al. in Akita University employed LTP (Low melting ThermoPlastic) as another candidate of liquefying fuels and demonstrated high regression rates comparable to paraffin fuels. Hori et al. in JAXA/ISAS employed glycidylazide-poly(ethylene glycol) (GAP-PEG) copolymers as high regression rate fuels and modified the combustion characteristics by changing the PEG mixing ratio. Regression rate improvement by changing internal ballistics is another stream of research. The author proposed a new fuel configuration named "CAMUI" in 1998. CAMUI comes from an abbreviation of "cascaded multistage impinging-jet" meaning the distinctive flow field. A CAMUI type fuel grain consists of several cylindrical fuel blocks with two ports in axial direction. The port alignment shifts 90 degrees with each other to make jets out of ports impinge on the upstream end face of the downstream fuel block, resulting in intense heat transfer to the fuel. Yuasa et al. in Tokyo Metropolitan University employed swirling injection method and improved regression rates more than three times higher. However, regression rate distribution along the axis is not uniform due to the decay of the swirl strength. Aso et al. in Kyushu University employed multi-swirl injection to solve this problem. Combinations of swirling injection and paraffin based fuel have been tried and some results show very high regression rates exceeding ten times of conventional one. High fuel regression rates by new fuel, new internal ballistics, or combination of them require faster fuel-oxidizer mixing to maintain combustion efficiency. Nakagawa et al. succeeded to improve combustion efficiency of a paraffin-based fuel from 77% to 96% by a baffle plate. Another effective approach some researchers are trying is to use an aft-chamber to increase residence time. Better understanding of the new flow fields is necessary to reveal basic mechanisms of regression enhancement. Yuasa et al. visualized the combustion field in a swirling injection type motor. Nakagawa et al. observed boundary layer combustion of wax-based fuels. To understand detailed flow structures in swirling flow type hybrids, Sawada et al. (Tohoku Univ.), Teramoto et al. (Univ. of Tokyo), Shimada et al. (ISAS), and Tsuboi et al. (Kyushu Inst. Tech.) are trying to simulate the flow field numerically. Main challenges are turbulent reaction, stiffness due to low Mach number flow, fuel regression model, and other non-steady phenomena. Oshima et al. in Hokkaido University simulated CAMUI type flow fields and discussed correspondence relation between regression distribution of a burning surface and the vortex structure over the surface.

• Korean Journal of Soil Science and Fertilizer
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• v.36 no.3
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• pp.163-179
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• 2003

Multifunctionality of agriculture which is not traded on the market now has been an important international issue in that it environmental and public benefits. We carried out to modify and to update the function of upland farming on flood prevention and fostering water resources. Economic values of environmental benefits were evaluated by replacement cost methods. Models to evaluate the function of preventing flood were selected as: (1)precipitation(flood-inducing) - runoff(A), (2) soil depth ${\times}$ soil air phase, (3) precipitation (flood-inducing) - runoff(B), (4) soil depth ${\times}$ effective porosity of soil. Models to estimate the function of fostering water resources were (1) saturated hydraulic conductivity (Ks) ${\times}$ duration of saturation(days) ${\times}$ (1-ratio of water flow directly into river), (2) precipitation ${\times}$ ratio of water fostered by rain resources ${\times}$ (area of upland/total land area), and (3) soil water retention quantity(under standing crop or tree) - SWRQ(in bare soil). Function of preventing flood was $883Mg\;ha^{-1}$ of water per year and 645 million Mg for the whole upland area. Function of fostering water resources was $94.1Mg\;ha^{-1}$ of water per year and 69 million Mg for the whole upland area. The value of flood-preventing function evaluated by replacement cost methods was estimated 1,428 billion won per year as compared to the cost for dam construction. The value of water resource fostering were estimated 8.6 billion won in the price of living water.

• Cross-Cultural Studies
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• v.42
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• pp.451-474
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• 2016

Analysis of the syntactic structure of the modern Chinese adverbs for time 'Cengjing (曾經)' and 'Yijing (已經)' was performed to examine the tenses and aspects of the terms. The corresponding Korean words were examined and the terms in both languages were compared. The syntactic structures used in China and South Korea were found to be different. We hope the study of the Chinese language will help Korean students. 'Cengjing (曾經)' specific projects with 'aspect' of, 'Past experience aspect', 'Past continuous aspect', 'Past continuous aspect' in the past tense. [ED: unclear, please reword] These correspond to '_었 (았)_', '_었었_' in the Korean language. 'Yijing (已經)' has 'finished phase' of concrete projects, 'Past experience aspect', 'Past continuous aspect', also has a specific project tense, the 'past tense', 'present tense', 'future tense', and so tense. [ED: unclear, please reword] Adjectives can also be modified with a 'change of status'. These correspond to '_었 (았)_', '_고_', '_었었_', '곧' etc. in Korean. 'Cengjing (曾經)' and the dynamic auxiliary 'Guo (過)' were compared to determine whether they have the aspect and tense features. However, 'Guo (過)' can only modify the predicate verb, so it possesses only aspect characteristics. 'Cengjing (曾經)' modifies the range more widely. 'Yijing (已經)' may be modified by the adverb 'Zai (在)' whereas 'Cengjing (曾經)' may not. Additionally, 'Yijing (已經)' can be modified by predicate adjectives and noun predicates, while 'Cengjing (曾經)' cannot.

• Cross-Cultural Studies
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• v.53
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• pp.103-130
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• 2018

The Chilean female writer María Luisa Bombal (1910 - 1980)'s "El ${\acute{a}}rbol$" (The Tree) (1939) tells the process of Brigida's epiphany. Brigida first tried to gain her father's love and failed, and later her husband's love and failed, then tried to substitute that love from men with solace from a tree. At the end of the novel, the epiphany occurs when the tree is cut down. In the present work, I explain the meaning of Brigida's epiphany, by comparing this Chilean short story with the Korean female writer Kim Chaewon(1946 - )'s "Trick of Water: A Kiss with Nothing" (2015). In this Korean short story, Kim insists that a woman who tries to find comfort in life through love with a man is destined to fail. I also examine the errors of the female characters' behaviors in these two short stories that led them to their self-destruction, trying to modify their behaviors in order to be loved by a man and their tendency to consider the man as everything in their life, and not as a part of their life. In order to explain the fated failure of finding comfort in life in the love of a man, I analyze the fleeting characteristic of acquiring an object of desire using Jacques Lacan's "Theory of Desire" and "The Destruction of the Elevated Object into the Dignity of the Thing." Thus, I conclude that women need to acknowledge that comfort in life cannot be found in the love of a man and that they should stop confining themselves to this fictitious characteristic of the dignified object called man.

• Journal of Life Science
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• v.29 no.2
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• pp.173-180
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• 2019

Amyloid ${\beta}$-protein ($A{\beta}$) is the principal component of senile plaques characteristic of Alzheimer's disease (AD) and elicits a toxic effect on neurons in vitro and in vivo. Many environmental factors, including antioxidants and proteoglycans, modify $A{\beta}$ toxicity. It is worthwhile to isolate novel natural compounds that could prove therapeutic for patients with AD without causing detrimental side effects. In this study, we investigated the in vitro neuroprotective effects of the ethyl acetate fraction of methanol extract of Ophiophogon japonicas (OJEA fraction). We used an MTT reduction assay to detect protective effects of the OJEA fraction on $A{\beta}_{25-35}$-induced cytotoxicity to PC12 cells. We also used a cell-based ${\beta}$-secretase assay system to investigate the inhibitory effect of the OJEA fraction on ${\beta}$-secretase activity. In addition, we performed an in vitro lipid peroxidation assay to evaluate the protective effect of the OJEA fraction against oxidative stress induced by $A{\beta}_{25-35}$ in PC12 cells. The OJEA fraction had strong protective effects against $A{\beta}_{25-35}$-induced cytotoxicity to PC12 cells and was strongly inhibitory to ${\beta}$-secretase activity, which resulted in the attenuation of $A{\beta}$ generation. In addition, the OJEA fraction significantly decreased malondialdehyde (MDA) content, which is induced by the exposure of PC12 cells to $A{\beta}_{25-35}$. Our results suggested that the OJEA fraction contained active compounds exhibiting a neuroprotective effect on $A{\beta}$ toxicity.

• Journal of Bio-Environment Control
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• v.28 no.2
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• pp.95-103
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• 2019

Temperature and relative humidity are important factors in crop cultivation and should be properly controlled for improving crop yield and quality. In order to control the environment accurately, we need to predict how the environment will change in the future. The objective of this study was to predict air temperature and relative humidity at a future time by using a multilayer perceptron (MLP). The data required to train MLP was collected every 10 min from Oct. 1, 2016 to Feb. 28, 2018 in an eight-span greenhouse ($1,032m^2$) cultivating mango (Mangifera indica cv. Irwin). The inputs for the MLP were greenhouse inside and outside environment data, and set-up and operating values of environment control devices. By using these data, the MLP was trained to predict the air temperature and relative humidity at a future time of 10 to 120 min. Considering typical four seasons in Korea, three-day data of the each season were compared as test data. The MLP was optimized with four hidden layers and 128 nodes for air temperature ($R^2=0.988$) and with four hidden layers and 64 nodes for relative humidity ($R^2=0.990$). Due to the characteristics of MLP, the accuracy decreased as the prediction time became longer. However, air temperature and relative humidity were properly predicted regardless of the environmental changes varied from season to season. For specific data such as spray irrigation, however, the numbers of trained data were too small, resulting in poor predictive accuracy. In this study, air temperature and relative humidity were appropriately predicted through optimization of MLP, but were limited to the experimental greenhouse. Therefore, it is necessary to collect more data from greenhouses at various places and modify the structure of neural network for generalization.

• Journal of The Korean Association For Science Education
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• v.41 no.3
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• pp.237-250
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• 2021

Teachers play a key role in designing a students' learning experience. Teachers are asked to interpret the context in which they are located and to adjust their practice to fit circumstantial needs based on their teacher agency. In this study, we explore the emergence of teacher agency in distance learning caused by COVID-19 and we analyze factors shaping the teacher agency. For this purpose, we interviewed six secondary science teachers who practiced distance learning in 2020. Semi-constructed interviews and their artifacts were collected and analyzed. This study shows that teacher agency is captured when they respond to circumstantial change and modify their practice to achieve their professional purpose or adjust their practice in space for maneuvering or keep their practice consistent. This study also analyzes the factors that affect the emergence of teacher agency in two dimensions. One is individual and the other is contextual. In the individual dimension, educational values shaped by his/her experiences and short/long-term goals for the future support the emergence of teacher agency. In the contextual dimension, there are collaborative and flexible culture shared by the community, co-operation within the teacher community, and material support. On the other hand, in the individual dimension, the teachers' sense of their role, and no reflection for own practice constrain the emergence of teacher agency, and in the contextual dimension, performativity discourse and strong requirement without guidance constrain the emergence of teacher agency. We suggest an effective lens for establishing a strategy that support teachers' professional practice and the emergence of teacher agency.

• Journal of the Korean Institute of Landscape Architecture
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• v.50 no.1
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• pp.68-77
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• 2022

The human thermal environment in an apartment complex located in Seoul was quantitatively analyzed to devise methods to modify human heat-related stresses in landscape and urban planning. Microclimatic data (air temperature, relative humidity, wind speed, and short- and long-wave radiation) were collected at 6 locations [Apt-center, roof (cement), roof (grass), ground, playground, and a tree-lined road] in the late spring and summer, and the data were used to estimate the human thermal sensation, physiological equivalent temperature (PET) and universal thermal climate index (UTCI). As a result, the playground location had the highest thermal environment, and the roof (grass) location had the lowest. The mean difference between the two locations was 0.8-1.1℃ in air temperature, 1.8-4.0% in relative humidity, and 7.5-8.0℃ in mean radiant temperature. In open space locations, the wind speed was 0.4-0.5 ms-1 higher than others. Also, a wind tunnel effect happened at the Apt-center location during the afternoon. For the human thermal sensation, PET and UTCI, the mean differences between the playground and roof (grass) locations were: 5.2℃ (Max. 11.7℃) in late spring and 5.4℃ (Max. 18.1℃) in summer in PET; and 3.0℃ (Max. 6.1℃) in late spring and 2.6℃ (Max. 9.8℃) in summer in UTCI. The mean differences indicated a level change in PET and 1/2 level in UTCI, and the maximum differences showed greater changes, 2-3 levels in PET, and 1-1.5 levels in UTCI. Moreover, the roof (grass) location gave 4.6℃ PET reduction and a 2.5℃ UTCI reduction in late spring, and a 4.4℃ PET reduction and a 2.0℃ UTCI reduction in the summer when compared with the roof (cement) location, which results in a 2/3 level change in PET and a 1/3 level in UTCI. Green infrastructure locations [roof (grass), ground, and a tree-lined road] were not statistically significant in the reduction of PET and UTCI in thermal environment modifying effects. The implementation of green infrastructure, such as rooftop gardens, grass pavement, and street tree planting, should be adopted in landscape planning and be employed for human thermal environment modification.

• Clean Technology
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• v.28 no.4
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• pp.269-277
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• 2022

With the recent development of the biological enzymatic reaction industry, lactic acid (LA) can be mass-produced from biomass sources. In particular, a catalytic process that converts LA into acrylic acid (AA) is receiving much attention because AA is used widely in the petrochemical industry as a monomer for superabsorbent polymers (SAP) and as an adhesive for displays. In the LA conversion process, NaY zeolites have been previously shown to be a high-activity catalyst, which improves AA selectivity and long-term stability. However, NaY zeolites suffer from fast deactivation due to severe coking. Therefore, the aim of this study is to modify the acid-base properties of the NaY zeolite to address this shortcoming. First, base promoters, Ca ions, were introduced to the NaY zeolites to tune their acidity and basicity via ion exchange (IE) and incipient wetness impregnation (IWI). The IWI method showed superior catalyst selectivity and stability compared to the IE method, maintaining a high AA yield of approximately 40% during the 16 h reaction. Based on the NH₃- and CO₂-TPD results, the calcium salts that impregnated into the NaY zeolites were proposed to exit as an oxide form mainly at the exterior surface of NaY and act as additional base sites to promote the dehydration of LA to AA. The NaY zeolites were further treated with KOH before calcium impregnation to reduce the total acidity and improve the dispersion of calcium through the mesopores formed by KOH-induced desilication. However, this KOH treatment did not lead to enhanced AA selectivity. Finally, calcium loading was increased from 1wt% to 5wt% to maximize the amount of base sites. The increased basicity improved the AA selectivity substantially to 65% at 100% conversion while maintaining high activity during a 24 h reaction. Our results suggest that controlling the basicity of the catalyst is key to obtaining high AA selectivity and high catalyst stability.