• Asia Pacific Journal of Business Review
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• 제6권2호
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• pp.61-76
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• 2022

Based on the concept of advertising expenditure, manufacturing firm performance, and enterprise life cycle, this research conducts the listed Chinese manufacturing listed in 2016-2018 as the research sampling and divides these listed companies into three periods: growth, maturity, and decline. Next, this paper conducts empirical research from three aspects: advertising expenditure or investment and manufacturing firm performance, lag effect of advertising expenditure, and outcome effect and lag effect of advertising investment. It is found that in different stages of manufacturing enterprises, different advertising expenditures will have different impacts on the performance of manufacturing enterprises. In the growth stage, the advertising investment of manufacturing enterprises will significantly affect the performance results of the current period, and there will be the long-term lag effect. In contrast, the mature stage of enterprises' advertising investment has a shorter period of lag effect, while in the recession stage, the mature stage of manufacturing enterprises' advertising investment will have a shorter period of lag effect. The empirical results are not significant. This study provides a reference for manufacturing enterprises in different stages in the decision-making of advertising investment.

• 전력전자학회논문지
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• 제27권2호
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• pp.126-133
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• 2022

This study proposes a suppression of zero sequence current (ZSC), which is caused by zero sequence voltage (ZSV) for a dual two-level inverter with single DC bus. Large output voltages enable the dual inverter with single DC bus to improve a system efficiency compared with single inverter. However, the structure of dual inverter with single DC bus inevitably generates ZSC, which reduces the system efficiency and causes a current ripple. ZSV is also produced by dead time, and its magnitude is determined by the DC bus and current direction. This study presents a novel space vector modulation method that allows the instantaneous suppression of ZSC. Based on a condition where a switching period is twice a sampling (control) period, the proposed control method is implemented by injecting the offset voltage at the primary inverter. This offset voltage is injected in half of the switching period to suppress the ZSC. Simulation and experiments are used to compare the proposed and conventional methods to determine the ZSC suppression performance.

• Environmental Sciences Bulletin of The Korean Environmental Sciences Society
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• 제2권2호
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• pp.169-179
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• 1998

This paper was performed to estimate interrelations between humus level of sediments and nutrient release from sediments in Dae-cheong reservoir. For investigations, sediments were sampled in June and October, in 1997 at fish farms, embayment, and the main stream of Dae-cheong reservoir. Items for investigation are as follows; water content, weight loss on ignition(IG), porosities of sediments, contents of element such as hydrogen, nitrogen, carbon, and nutrient release rates. Water contents and porosities were measured to conjecture the physical trait and grain size trait. Weight loss on ignition was measured to determine the contents of organic substance. For determination of the humus level of sediments, carbon and nitrogen contents were measured by elemental analyzer. As a result of elemental analysis, C/N ratio was determined in the range of $3.0\~13.1$. From the elemental analysis, humus level of Dae-cheong reservoir sediment was estimated from mesohumic state to oligotrophic state. For the determination of nutrient release rate, $PO_4-P$ and $NH_4-N$ concentrations of interstitial water and overlying water were measured. By using the concentration difference between interstitial water and overlying water and using the Fick's diffusion law, the release rates of phosphorus and nitrogen from the sediment samples were calculated. Release rates of nutrients which directly influence to the water quality were $0.05\~8.63mgP/m^2day$ and $4.99\~36.56mgP/m^2day$. It was found that release rate was measured higher in the 1st sampling period than in the 2nd sampling period. For the determination of phosphorus content in sediment, TPs were measured in 807\~1542{\mu}g/g$ in the 1st samling period and $677\~5238{\mu}g/g$ in the End samling period. Phosphorus release rate and phosphorus content were not interrelated each other.

• 한국수산과학회지
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• 제31권5호
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• pp.707-712
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• 1998

한국 남해 연근해에서 어획된 12종의 주요 어류 (표$\cdot$중충회유어 5종: 멸치, 숭어, 전어, 방어, 고등어: 연안암초어 3종: 조피볼낙, 참돔, 감성돔: 저서어 4종: 도다리, 붕장어, 넙치, 말쥐치)를 대상으로 하여 그들의 일반성분조성과 CHOL 및 $\alpha$-Toc 함량의 계절변화를 검토하였다. 지질과 수분함량은 역의 상관관계(r=-0.86, p<0.001)로 계절에 따라 뚜렸한 변화를 나타내었으나, 단백질 및 회분함량은 거의 변화가 없었다. 멸치, 전어, 감성돔, 도다리, 붕장어, 넙치, 말쥐치는 각각 12월, 10월, 11월, 9월, 1월, 1월, 11월에 지질함량이 높았고, 산란기에 해당하는 계절에 지질함량이 낮아 산란의 영향이 큰 어종이었다. 그러나 숭어, 방어, 고등어, 조피볼낙, 참돔의 지질함량 변화는 산란의 영향보다는 수온과 섭이량의 영향이 큰 것으로 생각되었다. CHOL의 함량변화는 지질함량변화와 정의 상관관계 (r=0.89, p<0.001)를 나타냈으나, $\alpha$-Toc 함량은 계절에 따른 변화가 인정되지 않았다.

• Toxicological Research
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• 제30권4호
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• pp.305-309
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• 2014

Recently, there has been an increase in the use of several nephrotoxicity biomarkers in preclinical experiments. In addition, it has been indicated that the result may have been influenced by secondary factors, such as sample storage condition or storage period. In this study, we have assessed the variation in urinary nephrotoxicity biomarkers as a result of urine storage conditions and storage period of the urine. Urine was sampled from specific pathogen-free Sprague-Dawley rats (19 weeks old), which were housed individually in hanged stainless steel wire mesh cages. Urine was stored at $20^{\circ}C$, at $4^{\circ}C$, or at $-70^{\circ}C$ after sampling. The levels of the biomarkers such as beta-2 microglobulin (B2M), cystatin-C (Cys-C), N-acetyl-${\beta}$-D-glucosaminidase (NAG), micro albumin (MA), micro protein (MP) were measured at 6, 24, 48 and 144 hr after sampling. The B2M level was significantly decreased at 6, 24, 48, and 144 hr compared to 0 hr at $-70^{\circ}C$ (p < 0.05, p < 0.01, p < 0.05, and p < 0.05, respectively) and 24 and 144 hr at $20^{\circ}C$ (p < 0.01, p < 0.01, respectively). The Cys-C level was significantly decreased at 144 hr compared to 0 hr at $4^{\circ}C$ (p < 0.01), at $20^{\circ}C$ (p < 0.05) and at $70^{\circ}C$ (p < 0.01). MP and MA levels were not different for 144 hr in all storage conditions. Taken together, B2M and Cys-C levels were modulated by storage temperature and period. For the enhancement of test accuracy, it is suggested that strict protocols be established for samples to minimize the effects of the storage conditions on the detected levels of biomarkers.

• Journal of Power Electronics
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• 제13권2호
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• pp.232-242
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• 2013

To obtain phase currents information in AC drives, shunt sensing technology is known to show great performance in cost-effectiveness and therefore it is widely used in low cost applications. However, shunt sensing methods are unable to acquire phase currents in certain operation conditions. This paper deals with the derivation of the boundary conditions for phase current reconstruction in three-shunt sensing inverters and proposes a voltage injection method to expand the measurable areas. As the boundary conditions are deeply dependent on the switching patterns, they are typically analyzed on the voltage vector plane for space vector pulse width modulation (SVPWM) and discontinuous pulse width modulation (DPWM). In the proposed method, the voltage injection and its compensation are conducted within one sampling period. This guarantees fast current reconstruction and the injected voltage is decided so as to minimize the current ripple. In addition to the voltage injection method, a sampling point shifting method is also introduced to improve the boundary conditions. Simulation and experimental results are presented to verify the boundary condition derivation and the effectiveness of the proposed voltage injection method.

• 아동학회지
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• 제33권4호
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• pp.19-34
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• 2012

This study investigated the differences in time use patterns and psychological states across daily activity contexts and interpersonal contexts, depending on the levels of school maladjustment among elementary school students. Using the Experience Sampling Method (ESM), 107 elementary school 6th grade students' daily time use patterns and psychological states across daily contexts were measured six times a day over a period of 4 days. Using the school maladjustment scale, an internal problem based school maladjusted group and an external problem based school maladjusted group were identified and selected. The daily time use patterns and psychological states of both school maladjusted groups were compared to those of the adjusted groups. The principle findings are as follows: first, the school maladjusted group students' daily time use patterns across daily activity contexts or interpersonal contexts did not differ from those of the students from the school adjusted group. Second, the school maladjusted group students experienced more negative emotions, lower concentration levels, and lower motivation levels across daily contexts than the school adjusted group students. These differences in motivation between the external problem school maladjusted group and adjusted group, however, were greater in the schoolwork context compared to the other daily activity contexts. The findings were discussed in the contexts of the daily experiences of child school maladjustment.

• 한국환경보건학회지
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• 제2권1호
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• pp.29-31
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• 1975

This experiment Was carried out under two points of view, from May 1st to the end of 1973. One was the comparative determination of the activation factor of Lead dioxide by kinds in measuring of Sulfur oxides concentration by $PbO_2$ cylinder method, and the other was the comparison that result with the record of auto analyzer. Five measuring sites were selected out of Seoul City. Three kinds of Lead dioxide made in Japan (B,C and D) were compared with Standard $PbO_2$ (A for use in Determination of Sulphur in the atmosphere, purity 99% up) made in British Institution, and monthly measuring was conducted at every sampling site. The recording by auto analyzer (Beckman Model 906-A $SO_2$ Analyzer) was conducted once or twice a month for 24 hours at each sampling site during the same period. And some significant results were obtained. 1. In comparative experiments to determine the activation degree of three kinds of Lead dioxide (B,C and D), the obtained correction factor of B reagent was 1.09, 1.16 in C and 1.30 in D against Standard $PbO_2$ (A). Therefore, it should be in need of standardization or clear statement about the reagents for use, in determination sulfur oxides by $PbO_2$ cylinder method. 2. Generally, the concentration of Sulfur dioxide by wilkins' convertion method from $SO_3$ showed about 20-30% higher than those by Auto analyzer.

• 한국대기환경학회지
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• 제14권1호
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• pp.1-10
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• 1998

Relationships between TSP and PM10 concentrations were evaluated using their respective data sets collected from Taegu and Kyeungsan areas during the period of December 1993 to November 1994. The collection of data was made using the gravimetric and $\beta$-ray absorption ($\beta$-MPM) methods for 7 days of every month from three urban sites in Taegu and one suburban site in Kyeungsan. Correlation coefficients between TSP and PM10 concentrations for these four sampling sites were found in the range of 0.85 $\sim$ 0.96. Correlation analysis was also conducted for $\beta$-PM concentration data that were measured only from the residential and commercial sites. The correlation coefficients between TSP and $\beta$-PM concentrations were 0.9 in the residential site and 0.8 in the commercial site. By contrast, the correlation coefficients between PM10 $\beta$-PM concentrations were almost identical for both the residential and commercial sites with a value of 0.88. The mean ratio for PM10 to TSP concentrations for all sites was appeared to be 0.68. The analysis of seasonal trends in PM10/TSP ratios showed that the contribution of PM10 to TSP concentrations was more significant during winter (0.70 $\sim$ 0.75) than during summer (0.61 $\sim$ 0.68). The results of this study may provide empirical informations on the compatability of aerosol data measured by different sampling methods.

• 대한약침학회지
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• 제15권3호
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• pp.7-12
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• 2012

Objective: This study aimed to summarize and analyze the usage of and the satisfaction levels with combined treatment including Oriental and Western medicine. Methods: We searched studies on the usage of and the satisfaction levels with combined treatment including Oriental and Western medicine over the past 10 yrs (2001-2011) from 3 Korean databases (National Assembly Library, Research Information Service System, and National Discovery for Science Leaders). The reviewers also conducted a summarizing analysis by sampling the literature according to the type of study, study period, region, study subjects, sample size, type of sampling, research method, data analysis, study instruments, main results, etc. Results: When the main results of six studies on combined treatment usage and satisfaction levels were considered together, the most important decisive factor in determining the usage of combined treatment was the illness of the patient, followed by the patient's occupation, sex, age, education, marital status, religion, treatment cost, and treatment results. In addition, the most important factor that determined satisfaction levels with combined treatment was age, followed by education, religion, income, health status, treatment procedures, staff attitude, and cleanliness. Conclusions: Elderly patients with musculoskeletal, cerebro-vascular, and circulatory system illnesses are more likely to prefer combined treatment over independent Oriental or Western treatment and are more likely to request specialized, adjusted medical care.