• Journal of the Semiconductor & Display Technology
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• v.11 no.1
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• pp.61-65
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• 2012

In this study, for use of carbon nanotubes (CNTs) as a cold cathode of x-ray tubes, we examine the effects of selective growth of CNTs on their field emission properties and long-term stability. The selective growth of CNTs was performed by selectively etching the catalyst layer which was used for CNTs' nucleation. CNTs were grown on conical-type tungsten substrates using an inductively-coupled plasma chemical vapor deposition system. For all the grown CNTs, their morphologies and microstructures were analyzed by field-emission scanning electron microscope and Raman spectroscopy. The electron-emission properties of CNTs and the long-term stability of emission currents were measured and characterized according to the CNTs' growth position on the substrate.

• Clinical and Experimental Pediatrics
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• v.57 no.3
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• pp.101-109
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• 2014

The use of glucocorticoids (GCs) in the perinatal period is suspected of being associated with adverse effects on long-term neurodevelopmental outcomes for preterm infants. Repeated administration of antenatal GCs to mothers at risk of preterm birth may adversely affect fetal growth and head circumference. Fetal exposure to excess GCs during critical periods of brain development may profoundly modify the limbic system (primarily the hippocampus), resulting in long-term effects on cognition, behavior, memory, co-ordination of the autonomic nervous system, and regulation of the endocrine system later in adult life. Postnatal GC treatment for chronic lung disease in premature infants, particularly involving the use of dexamethasone, has been shown to induce neurodevelopmental impairment and increases the risk of cerebral palsy. In contrast to studies involving postnatal dexamethasone, long-term follow-up studies for hydrocortisone therapy have not revealed adverse effects on neurodevelopmental outcomes. In experimental studies on animals, GCs has been shown to impair neurogenesis, and induce neuronal apoptosis in the immature brains of newborn animals. A recent study has demonstrated that dexamethasone-induced hypomyelination may result from the apoptotic degeneration of oligodendrocyte progenitors in the immature brain. Thus, based on clinical and experimental studies, there is enough evidence to advice caution regarding the use of GCs in the perinatal period; and moreover, the potential long-term effects of GCs on brain development need to be determined.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.47 no.2
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• pp.108-115
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• 2002

The effects of long-term fertilization on soil properties and nutrient availability are not well documented for cassava cultivation in Vietnam. In 1990, a field research plots were established with 12 treatments to test the effect of different rates of nitrogen (N), phosphorus (P) and potassium (K) on soil properties in Acrisols at Thai Nguyen University in Northern Vietnam. In 1999, composite soil samples (0 to 20cm depth) were collected from eight selected plots for measurements of nutrient supply rates by ion exchange membrane probes and for growing corn and canola in a growth chamber with and without added lime. Generally, long-term nitrogen (N) fertilization increased available N supply rates but decreased available potassium (K) and magnesium (Mg). Long-term phosphorus(P) applications increased canola N, calcium (Ca) and Mg uptake. Canola P uptake increased with increased P rates only when lime was added. Long-term K applications increased canola N, K, Ca, Mg uptake but only significantly increased corn N uptake. Liming significantly increased uptake of N, P, K, Ca, Mg and S for both corn and canola. However, N $H_{4-}$N, K and Mg soil supply rates were reduced when lime was added, due to competition between Ca from the added lime and other nutrients.

• Korea Journal of Hospital Management
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• v.13 no.2
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• pp.64-85
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• 2008

This study purports to investigate the determinant of job satisfaction among workers working at Long-term care hospitals. The independent variables contain three groups of determinants: organizational characteristics variables(job autonomy, job variety, distributive justice, role conflict, supervisor support, job suitability, job significance, job security, organizational support, job growth, promotional opportunity), environmental variables(job opportunity), and psychological variables (met expectation, job efficacy, positive affectivity, and negative affectivity). The sample used in this study consisted of 250 workers from 4 Long-term care hospitals nationwide. Data were collected with self-administered questionnaires and analyzed using multiple regression analysis. The results of the study are as follows: 1) the following variables, listed in order of size, have significant effects on job satisfaction: negative affectivity(-), job significance(+), job growth(+), age(+), positive affectivity(+), organizational support(+), job opportunity(-). 2) the variance of job satisfaction explained by the variables used in the study are 53.8%. When demographic variables added to Model I, job satisfaction explained by variables are 55.4%. 3) the results of this study indicate that three variables of negative affectivity, job significance, job growth are especially important for improving the level of job satisfaction among workers at Long-term care hospitals.

• Clinical and Experimental Reproductive Medicine
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• v.50 no.4
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• pp.292-298
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• 2023

Objective: Ovarian torsion is a gynecological disorder that causes ischemia-reperfusion injuries in the ovary. Our study investigated berberine's short- and long-term effects on ovarian ischemia-reperfusion injuries. Methods: This study included 28 Wistar albino female rats weighing 180 to 220 g, which were divided into four groups: sham (S), torsion/detorsion (T/D), torsion/ detorsion+single dose berberine (T/D+Bb), and torsion/detorsion+15 days berberine (T/D+15Bb). The torsion and detorsion model was applied in all non-sham groups. In the T/D+Bb group, a single dose of berberine was administered, while in the T/D+15Bb group, berberine was administered over a period of 15 days. After the rats were euthanized, their ovaries were excised. The left ovaries were used for histopathologic evaluation, which included ovarian injury scoring and follicle count, while the right ovaries were used for biochemical analyses (tissue transforming growth factor-β [TGF-β] and alpha-smooth muscle actin [α-SMA] levels). Results: The histopathologic evaluation scores for the ovaries were significantly lower in the T/D+B group (p<0.05) and the T/D+15B group (p<0.005) than in the T/D group. The follicle counts in the T/D group were lower than those in both the sham and treated groups (p<0.005). The TGF-β levels were significantly lower in the T/D+15B group (p<0.005), whereas the α-SMA levels did not show a significant difference. Conclusion: Both short- and long-term berberine use could potentially have therapeutic effects on ovarian torsion. Long-term berberine use exhibited anti-inflammatory effects by reducing TGF-β levels, thereby preventing ischemia-reperfusion injuries. Therefore, we suggest that long-term berberine use could be beneficial for ovarian torsion.

• Journal of Korea Trade
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• v.26 no.6
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• pp.41-60
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• 2022

Purpose - The policy implications of free trade agreements have traditionally been a matter of debate among economists. The official signing of the Korea-China Free Trade Agreement provides economists with a quasi-natural experiment to analyze the FTA's policy effects. This article aims to more accurately understand the impact of Korea's FTA accession on the macro economy. Design/methodology - This study adopts the counterfactual method based on panel data to find common factors in the generation process of macro data to fit the counterfactual path, to accurately evaluate the effect of the macro policy. Findings - Our research results show that the signing of the Korea-China FTA has a relatively significant short-term positive effect on Korea's economic growth. On average, Korea's real GDP growth rate has increased by 2.1%. This study finds evidence in support of FTA signing not having a significant impact on Korea's GDP growth in the long run. Additionally, we evaluated the impact of the FTA on Korea's imports and exports and found that it had a significant positive impact in the short term, but the trade effect of the FTA is significantly affected by the external macro-environment. Originality/value - First, this study uses macro panel data at the national level to examine the impact of the Korea-China FTA on Korea, and more accurately describes the policy effect of the FTA. Second, our empirical results show that the Korea-China FTA policy impact is subject to occasional changes in the external environment, such as the geopolitical conflict (crisis) between Korea and China, and the US-China trade war. Finally, the analysis shows that the short-term effect of FTA is significant but the long-term is uncertain, which provides empirical evidence for the debate on whether joining FTA can promote national economic growth.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.4
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• pp.249-256
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• 1997

To identify the long-term influence of acid rain treatment on tree growth, acid rain of various composition (pH 2.0, pH 4.0 and pH 5.6 as control) was applied to several landscape trees for five months (April through August, 1991). Tree height, pH values and $Al^{3+}$ concentration in soil were investigated. Acid rain treatments seemed to promote height growth in the first year (1991), but have become an inhibiting factor over five years. All of coniferous species and most broad-leaved species, except Acer ginnala, showed opposite trends in height responses to acid rain treatments between the first (1991) and last (1996) year. In contrast, Acer ginnala showed similar trends to acid rain treatments in the height growth between 1991 and 1996. This result suggested that Acer ginnala has a characteristic adapability to acid rain stress. pH values of surface soil were lower than those of 30 cm soil depth. This fact suggested that acid rain treatments made surface soil acidic condition. In addition, physiological characteristics (photosynthesis, stomatal condition and biomass) have to be investigated to identify the relationship between long-term effects of $AL^{3+}$ concentration and growth.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• v.25 no.2
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• pp.89-94
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• 2014

Objectives : This study was conducted naturalistically in order to observe the long-term effects of attention-deficit hyperactivity disorder (ADHD) medications on growth rates among Korean school-aged boys with ADHD. Methods : Participants in the study were boys with ADHD aged 6 to 11 years who have taken ADHD medication, methylphenidate (extended release) or atomoxetine. They attended scheduled visits monthly or bimonthly for clinical assessment with measurement of height and weight. In this study, 35 boys with ADHD (mean age at baseline=$7.90{\pm}1.77$ years ; mean age at endpoint= $12.54{\pm}1.91$ years) were included, with a mean follow-up period of 4.64 years (${\pm}1.62$ years), ranging from 2 to 9.7 years. Height, weight, and body mass index (BMI) measurements were converted to "age-corrected Z-scores" using data from Growth Charts provided by the Korean Center for Disease Control and Prevention from 2007. Results : Age-corrected endpoint growth parameters (height, weight, BMI Z-scores) did not differ significantly from the baseline values (height t=0.027 ; weight t=-0.61 ; BMI t=-1.86, in paired t-test). Especially high correlation was observed between the baseline and endpoint height Z-scores (r=0.876, p<.001), for which the coefficient of determination $r^2$ was 0.767, meaning that the amount of variability in endpoint height Z-scores explained by the baseline height Z-scores was 76.7%. Conclusion : Our results suggested that the long-term effects of ADHD medications on growth parameters to be tolerable in Korean school-aged boys with ADHD.

• Journal of Food Hygiene and Safety
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• v.1 no.2
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• pp.115-120
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• 1986

This experiment was carried out to develop long-term preservable meat products by controlling a water activity which has a potential inhibitory effects on the growth of microorganism and germination of spore. For this purpose the accuracy of instrument for the measurement of water activity, electric hygrometer was used for this study as well as water activity of final products were investigated according to the various amounts of different kinds of additives. Spore of Bacillus spp, Clostridium sporogenes and Cl. botulinum were inoculated to the meat products with different aw and their growth states in $25^{\circ}C$ were observed to find out the lowest aw which inhibit their growth (aw 0.950).

• Asia-Pacific Journal of Business
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• v.14 no.1
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• pp.73-91
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• 2023

Purpose - The purpose of this study is to re-examine the disclosure effect of stock splits and long-term performance after stock splits using stock split data over the past 10 years, and infer the motivation (signal or opportunism) of stock splits. In addition, we focus on exploring the determinants of the short- and long-term market response to stock splits. Design/methodology/approach - We measure the short-term market response to a stock split and the long-term stock performance after the stock split announcement using the event study method. We analyze whether there is a difference in the long-term and short-term market response to a stock split according to various company characteristics through univariate analysis and regression analysis. Findings - In the case of the entire sample, a statistically significant positive excess return is observed on the stock split announcement date, and the excess return during the 24-month holding period after the stock split do not show a difference from zero. In particular, the difference between short-term and long-term returns on stock splits is larger in companies with a large stock split ratio, small companies, large growth potential, and companies with a combination of financial events after a stock split. Research implications or Originality - The results of this study suggest that at least the signal hypothesis for a stock split does not hold in the Korean stock market. On the other hand, it suggests that there is a possibility that a stock split can be abused by the manager's opportunistic motive, and that this opportunism can be discriminated depending on the size of the stock split, corporate characteristics, and financing plan.