• Analytical Science and Technology
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• v.17 no.6
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• pp.496-513
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• 2004

This study was carried out to evaluate the performance of sampling and analytical methodology used for the measurement of toxic volatile organic compounds (VOCs) in the ambient air. VOCs were determined by the adsorbent tube sampling and automatic thermal desorption coupled with GC/MSD analysis. Target analytes were 33 compounds including major aromatic compounds such as BTEX, and halogenated compounds. The methodology was investigated with a wide range of different adsorbents which are commercially available and have been frequently adopted for the VOC measurement. A total of 10 adsorbents were tested in this study: 6 carbon-based adsorbents such as Carbotrap, Carbopack B, Carbosieve S-III, Carboxen 1000, Carbotrap C, Activated Charcoal; and 4 polymer-based adsorbents including Tenax, Porapak Q, Chromosorb 102, and Chromosorb 106. The sampling performance was evaluated with respect to the sampling capacity of VOCs with single-adsorbent and multiple-adsorbents methods for standard samples and field samples. As a result, the best adsorbents for single-adsorbent method in the sampling of toxic organic compounds (including benzene, toluene, xylenes etc.) appeared to be Carbotrap, Carbopack B and Tenax TA. On the other hand, Chromosorb 102, Chromosorb 106 and Porapak Q were found to be unsuitable adsorbents for VOC measurement based on thermal desorption method. Multi-adsorbent packings were evaluated with 4 carbon-based adsorbents, which classified by 3 combination sets of double adsorbents and 2 combination sets of triple adsorbents. The results indicated that the most suitable combination for toixc VOC measurements is Carbotrap C with Carbotrap. Multi-sorbents tubes packed with a strong adsorbent such as Carbosieve S-III or Carboxen 1000 were found to be relatively unsuitable for several compounds, not only owing to the effect of migration of adsorbed compounds from weaker adsorbent to stronger adsorbent, but to hydrophobic nature of the adsorbents. Therefore, it should be addressed that selection of a proper adsorbent (or combination of multi sorbents) is extremely important to obtain reliable data for the concentrations of toxic VOCs in indoor and outdoor environments.

• Korean Journal of Environment and Ecology
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• v.38 no.3
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• pp.293-309
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• 2024

This study was conducted to provide basic data on the structure of the Carpinus turczaninowii community and the characteristics of the habitat environment for ex situ conservation. To identify the current ecological environment, 27 plots (each measuring 100m²) were selected for analyzing the detailed structure of plant communities in Anmyondo Isl.(Jungjangri San 14-217), Hwanggumsan Mt., Gayasan Mt.(Wonhyobong) and Palbongsan Mt.. The research methodology employed in this study was qualitative analysis. The TWINSPAN classification yielded a total of seven distinct communities. Group I represents the C. turczaninowii - Quercus mongolica community, Group II represents the C. turczaninowii - Pinus densiflora community, Group III represents the C. turczaninowii - P. densiflora community, Group IV represents the C. turczaninowii - Q. mongolica community, Group V represents the C. turczaninowii - Q. variabilis community, Group VI represents the C. turczaninowii - Prunus serrulata Lindl. var. pubescens community, and Group VII represents the C. turczaninowii - Styrax japonicus community. The species diversity ranged from 0.8056 to 1.1568, the importance value ranged from 0.1214 to 0.3024, and the similarity index ranged from 9.37% to 36.36%. Based on the correlation analysis of six environmental factors for the seven communities using RDA ordination, the results indicate that on the first axis, Altitude, Crown density, Bare rock, and Slope exhibited a positive correlation. In the C. turczaninowii - P. densiflora community (Group III) and C. turczaninowii - Q. mongolica community (Group IV), altitude, bare rock, and slope were analyzed as factors influencing vegetation distribution. In the C. turczaninowii - Q. variabilis community (Group V), C. turczaninowii - P. serrulata Lindl. var. pubescens community (Group VI), and C. turczaninowii - S. japonicus community (Group VII), crown density was analyzed as a factor influencing vegetation distribution.

• The Journal of Industrial Distribution & Business
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• v.9 no.5
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• pp.63-72
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• 2018

Purpose - This work analyzes, in detail, the specification of vector error correction model (VECM) and thus examines the relationships and impact among seven economic variables for USA - balance on current account (BCA), index of stock (STOCK), gross domestic product (GDP), housing price indices (HOUSING), a measure of the money supply that includes total currency as well as large time deposits, institutional money market funds, short-term repurchase agreements and other larger liquid assets (M3), real rate of interest (IR_REAL) and household credits (LOAN). In particular, we search for the main explanatory variables that have an effect on stock and real estate market, respectively and investigate the causal and dynamic associations between them. Research design, data, and methodology - We perform the time series vector error correction model to infer the dynamic relationships among seven variables above. This work employs the conventional augmented Dickey-Fuller (ADF) and Phillips-Perron (PP) unit root techniques to test for stationarity among seven variables under consideration, and Johansen cointegration test to specify the order or the number of cointegration relationship. Granger causality test is exploited to inspect for causal relationship and, at the same time, impulse response function and variance decomposition analysis are checked for both short-run and long-run association among the seven variables by EViews 9.0. The underlying model was analyzed by using 108 realizations from Q1 1990 to Q4 2016 for USA. Results - The results show that all the seven variables for USA have one unit root and they are cointegrated with at most five and three cointegrating equation for USA. The vector error correction model expresses a long-run relationship among variables. Both IR_REAL and M3 may influence real estate market, and GDP does stock market in USA. On the other hand, GDP, IR_REAL, M3, STOCK and LOAN may be considered as causal factors to affect real estate market. Conclusions - The findings indicate that both stock market and real estate market can be modelled as vector error correction specification for USA. In addition, we can detect causal relationships among variables and compare dynamic differences between countries in terms of stock market and real estate market.

• Korean Journal of Social Welfare
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• v.67 no.2
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• pp.285-310
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• 2015

The purpose of this study is to verify qualitatively and quantitatively practitioners' perceptions of functions and roles of community child center which plays a pivotal role in afterschool care in Korea. To achieve its purposes, we investigate environments, services, workers, service users, and delivery systems of community child center. As a result, 4 types of perception of community child center(service integration-oriented type focusing on professional workers, care-oriented type based on child care center's physical environment, delivering service-oriented type working in collaboration with schools, and individual case management-oriented type) were examined. These results were also classified into two categories. One focused on the importance of workers and supports for service environments. The other focused more on the functions of community child center to find commonality and originality in other afterschool care systems. This study can be valuable in understanding practitioners' different perception on functions and roles of community child center which have not yet been confirmed statistically. The results allow us to apply diverse practitioners' perceptions to the practice, and to elicit discussions regarding improved practice directions for managing community child center. It also can provide useful baseline data in policy decisions and enforcement.

• The Korean Journal of Pesticide Science
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• v.9 no.3
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• pp.199-204
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• 2005

The herbicidal activities against barnyardgrass (Echinochloa crus-galli) by R-groups on the hexahydroisoindol-1-one ring of new 2-(4-chloro-5-(2-chloroallyloxy)-2-fluorophenyl) -3-thioalkoxy-2,3,4,5,6,7-hexahydroisoindol-1-one derivatives were studied using molecular holographic quantitative structure-activity relationships (HQSAR) methodology. Based on the results, the statistical results of the optimised HQSAR model (I-2) exhibited the best predictability and fitness for the herbicidal activities based on the cross-validated value ($r^2_{cv.}$ or $q^2=0.714$) and non-cross-validated value ($r^2_{ncv.}=0.922$), respectively. From the based graphical analyses of atomic contribution maps, herbicidal activities against barnyardgrass were confirmed depends upon the C4-C6 atoms of hexahydroisoindoline-l-one ring, carbon atom of ortho-position and meta-methyl group of 3-tolylthio substituent (8).

• Proceedings of the Korean Society of Crop Science Conference
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• 2004.04a
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• pp.12-27
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• 2004

Thanks to spectacular advances in the techniques for identifying proteins separated by two-dimensional electrophoresis and in methods for large-scale analysis of proteome variations, proteomics is becoming an essential methodology in various fields of plant sciences. Plant proteomics would be most useful when combined with other functional genomics tools and approaches. A combination of microarray and proteomics analysis will indicate whether gene regulation is controlled at the level of transcription or translation and protein accumulation. In this review, we described the catalogues of the rice proteome which were constructed in our program, and functional characterization of some of these proteins was discussed. Mass-spectrometry is a most prevalent technique to identify rapidly a large of proteins in proteome analysis. However, the conventional Western blotting/sequencing technique us still used in many laboratories. As a first step to efficiently construct protein data-file in proteome analysis of major cereals, we have analyzed the N-terminal sequences of 100 rice embryo proteins and 70 wheat spike proteins separated by two-dimensional electrophoresis. Edman degradation revealed the N-terminal peptide sequences of only 31 rice proteins and 47 wheat proteins, suggesting that the rest of separated protein spots are N-terminally blocked. To efficiently determine the internal sequence of blocked proteins, we have developed a modified Cleveland peptide mapping method. Using this above method, the internal sequences of all blocked rice proteins (i. e., 69 proteins) were determined. Among these 100 rice proteins, thirty were proteins for which homologous sequence in the rice genome database could be identified. However, the rest of the proteins lacked homologous proteins. This appears to be consistent with the fact that about 30% of total rice cDNA have been deposited in the database. Also, the major proteins involved in the growth and development of rice can be identified using the proteome approach. Some of these proteins, including a calcium-binding protein that fumed out to be calreticulin, gibberellin-binding protein, which is ribulose-1,5-bisphosphate carboxylase/oxygenase activate in rice, and leginsulin-binding protein in soybean have functions in the signal transduction pathway. Proteomics is well suited not only to determine interaction between pairs of proteins, but also to identify multisubunit complexes. Currently, a protein-protein interaction database for plant proteins (http://genome .c .kanazawa-u.ac.jp/Y2H)could be a very useful tool for the plant research community. Recently, we are separated proteins from grain filling and seed maturation in rice to perform ESI-Q-TOF/MS and MALDI-TOF/MS. This experiment shows a possibility to easily and rapidly identify a number of 2-DE separated proteins of rice by ESI-Q-TOF/MS and MALDI-TOF/MS. Therefore, the Information thus obtained from the plant proteome would be helpful in predicting the function of the unknown proteins and would be useful in the plant molecular breeding. Also, information from our study could provide a venue to plant breeder and molecular biologist to design their research strategies precisely.

• The Korean Journal of Pesticide Science
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• v.9 no.4
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• pp.279-286
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• 2005

The herbicidal activities against pre-emergence barnyard grass (Echinochloa crus-galli) by a series of new 2-(4-(6-chloro-2-benzoxazolyloxy)phenoxy)-N-phenylpopionamide derivatives as substrate molecule were studied using molecular holographic (H) quantitative structure activity relationships (HQSAR) methodology. From the based on the findings, the higher herbicidal active compounds are predicted by the derived HQSAR model. The best HQSAR model (VI-1) was derived from fragment distinction combination of atoms/bonds in fragment size, $7{\sim}10$bin. The herbicidal activities from atomic contribution maps showed that the activity will be able to increased according to the R-substituents variation of the N-phenyl ring and change of 6-chloro-2-benzoxazolyloxy group. Based on the results, the statistical results of the best HQSAR model (VI-1) exhibited the best pedictability and fitness for the herbicidal activities based on the cross-validated value ($q^2=0.646$) and non cross-validated value ($r^2_{ncv.}=0.917$), respectively. From the graphical analyses of atomic contribution maps, it was revealed that the lowest herbicidal activitics depends upon the 4-(6-chloro-2-benzoxazolyloxy)phenoxy group ($pred.pI_{50}=-3.20$). Particularly, the R=4-fluoro, X=isobutoxy substituent (P2) of (X)-phenoxy-N-(R)-phenylpropionamide derivative is predicted as the highest active compound ($pred.pI_{50}=9.12$).

• Journal of Distribution Science
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• v.13 no.3
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• pp.69-77
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• 2015

Purpose - The purpose of this study is to examine whether the cash policies of retail firms listed on Korean stock markets are consistent with the evidence provided in the study of Almeida et al. (2004). Liquidity management is an important issue for financially constrained firms relative to financially unconstrained firms. Because there are few sources of external funding, the optimal liquidity policies of financially constrained firms should reflect their own earnings or cash inflows to create opportunities for current and future real investments. According to this simple idea, we estimate the sensitivity of cash to cash flows and simply check whether the estimated sensitivity to cash flows of the cash retained by constrained retail firms is greater than that of the cash retained by unconstrained retail firms. Through this work, we aim to explain why the cash policies of the retail firms listed on the Korean stock markets differ from those of listed manufacturing enterprises. Research design, data, and methodology - To explain a firm's cash holdings, we use only three explanatory variables: earnings before interest and taxes (EBIT), Tobin's q, and size. All the variables are defined as the value of the numerator divided by aggregate assets. Thanks to this definition, it is possible to treat all the sample firms as a single large firm. The sample financial data for this study are collected from the retail enterprises listed on the KOSPI and KOSDAQ markets from 1991 to 2013. We can obtain these data from WISEfn, the financial information company. This study's methodology has its origin in Keynes's simple idea of precautionary liquidity demand: When a firm faces financial constraints, cash savings from earnings or cash inflows become important from the corporate finance perspective. Following this simple idea, Almeida et al. (2004) developed their theoretical model and found empirical evidence that the sensitivity of cash to cash flows varies systematically according to different types of financing frictions. To find more empirical evidence for this idea, we examined the cash flow sensitivity of the cash held by Korean retail firms. Results - Through several robustness tests, we empirically showed that financially constrained Korean retail firms display significant positive propensity to save cash from earnings before interest and taxes, while the estimated cash flow sensitivity of the cash held by unconstrained retail firms is not significant. Despite the relatively low earnings of retail firms, their sensitivity is three times greater than that of manufacturing enterprises. This implies that Korean retail firms have greater intentions of facilitating future investments rather than current investments. Conclusions - The characteristics of the cash policies of Korean retail firms differ from those of manufacturing firms. This contrast may be attributable to industry-oriented policy planning, regulations, and institutional differences. However, the industrial policymakers should observe signals of the long-term growth options of retail firms based on their high propensity to save from their cash inflows.

• Geotechnical Engineering
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• v.13 no.6
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• pp.95-106
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• 1997

A pressuremeter is an expandable tube which is placed in the soil, and then expanded under controlled condition against the soil. From this test a pressure expansion curve of the soil can be obtained. However soil disturbance during the test has significant influence on the results of tests. A general governing equation for pressuremeter test can be theoretically derived on the basis of the hyperbolic soil model and the cavity expansion theory. The curve fitting technique was used to establish the pressure-strain curve without disturbance of soil during testing. This interpretation makes use of both the loading and unloading portions of the test. An interpretation methodology is described and illustrated with pressuremeter test data carried out in the weathered granitic soil to estimate initial shear modulus. Standard penetration test is a very common site investigation technique in Korea. Therefore the blow counts of standard penetration test are discussed by comparing them with initial shear modulus.

• Journal of Korean Society of Forest Science
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• v.90 no.4
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• pp.488-494
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• 2001

This study was conducted to investigate forest ecosystem assessment which were widely used in Germany and Austria. The study area, Mt. Teawha, is located at Kwangju, Kyunggi-Do province. The methodology of this study considered the following factors. First forest types were classified accoding to species composition and age of tree layer. Naturalness, diversity and rerenees of each forest type were classified into 5 level. Finally, the forest types were assessed by synthesizing those 3 factors. Qurecus mongolica- and valley forest type over 300m was classified as naturalness 4 and Qurecus accustima, Quercus accusitima and Q. variabilis were as naturalness 3. The plantation types on the lower slope showed the level of naturlness 1 or 2. Diversity was similer to naturalness. But indices were different from each other. In the case of Larix leptolepsis plantations, naturalness indicated 1, while diversity showed 3. The valley forest type, wet forest and forest edge were classified into rare forest type. It was concluded that this method could be more efficient method comparing with existing method for assessment of naturality and thereby could contribute for biodiversity conservation in Korea.