• Bulletin of the Korean Chemical Society
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• v.6 no.5
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• pp.291-295
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• 1985

The efficiency of photosensitization of methyl linoleate (ML) oxidation by N-acetyl-L-trypophan(NAT) and 3-methyl indole(scatole) was markedly enhanced by increased concentration of ML in ethanol solution. The fluorescence intensities of sensitizers were observed to be quenched by ML, indicating that ML interacts with the indole excited singlet state. The inhibition of photosensitization by azide demonstrated a possible role of singlet oxygen in the photosensitization. The steady state kinetic treatment of azide inhibition of photosensitization was expected to show linear increase of reciprocal yield of ML oxidation product vs. reciprocal ML concentration at constant azide concentration, but the actual slope was nonlinear. This indicates another competing reaction involved in the photosensitization, As a possible competing reaction, electron transfer from ML to the excited sensitizer was proposed, since the measured fluorescence quenching rate constant closely resembled electron transfer rate constant determined from ML concentration dependence of oxidation product formation.

• Journal of Electrochemical Science and Technology
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• v.15 no.3
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• pp.427-435
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• 2024

Here we introduce a new method for characterizing the constant phase element (CPE) in electrochemical systems using cyclic voltammetry (CV), presenting an alternative to the conventional electrochemical impedance spectroscopy (EIS) approach. While CV is recognized for its diagnostic capabilities in electrochemical analysis, it traditionally encounters difficulties in accurately measuring CPE systems due to a lack of clear linearity with scan rates, unlike capacitors. Our research demonstrates a linear relationship between current and scan rate on a log-log plot, enabling the calculation of n and Y₀ values for CPE from the slopes of these linear relationships. For validation of our method, it is applied to two kinds of capacitors and the results agree with those measured by EIS. Although EIS is known to be accurate in measuring CPE systems, our alternative approach offers a timely and reasonably precise diagnostic tool, balancing between ease of use and accuracy, especially beneficial for preliminary assessments before conducting further in-depth analysis.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.33-43
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• 2014

Recently, the case to construct the structure on the soft clayey ground has increased and in order to the reduction of the cost of construction and maintenance on the social infrastructure facilities we have been trying to improve the soft clayey ground using the existing methods such as the pre-loading method and the vertical drain method. Like this, when various ground improvement methods are applied on the soft clayey ground, a long-term consolidation settlement will be key issue due to low permeability coefficient of cohesive soil. According to existing research results that relate to the consolidation settlement, the loading periods for existing the standard consolidation test (Oedometer test) to obtain the consolidation parameters are needed for minimum ten days or more. Therefore, in this study, the standard consolidation test (24 hours step-loading) and constant strain rate consolidation test changed by strain rate was performed using the remolded marine clay on Gwangyang bay composed of a soft clayey ground of the south-west coast. From the laboratory test results, the characteristics of compression, strain-effective stress relations by constant strain rate and the variation characteristic of the pore water pressure by different of loading speed and the relation between consolidation parameters and constant strain rate are compared and analyzed.

• Journal of Korean Society of Forest Science
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• v.100 no.2
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• pp.305-313
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• 2011

Fertilization is essential to seedling production in nursery culture, but excessive fertilization can contaminate surface and ground water around the nursery. The objective of this study was to find optimal fertilization practice of container seedling production for reducing soil and water contamination around the nursery without compromising seedling quality. This study was conducted to investigate growth performance, photosynthesis, chlorophyll fluorescence, and chlorophyll contents of Liriodendron tulipifera growing under three different fertilization treatments (Constant rate, Three-stage rate, and Exponential rate fertilization). Root collar diameter, height, and biomass of L. tulipifera were the highest at Constant treatment. Like growth performance, seedling quality index (SQI) were higher at Constant than at other treatments, but not significantly different among treatments. L. tulipifera showed good photosynthetic capacity at all treatments. Photochemical efficiency and chlorophyll contents were significantly lower at Exponential than at other treatments. Therefore, Exponential fertilization which is 50% fertilizer of other treatments would maximize seedling growth and minimize nutrient loss.

• The Mathematical Education
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• v.61 no.3
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• pp.419-439
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• 2022

This study is based on Freudenthal's mathmatising process and the didactical phenomenology of linear function concept, I have described and examined the process in which students represent the constant rate of change into tables, graphs and equations and, in this way, how they construct mental objects and essence of the linear function concept. The students used the proportionality as composite units, when they represented the phenomenon with constant rate of change into tables. When representing in graphs, all but one student represented it into a line. There were differences among the students in the level they were using the given conditions, co-variation perspective, and corresponding rules when formulating equations. The students compared the relationship between two variables in a multiplicative way, and under the guidance of teachers they reached to the understanding that its relationship becomes a constant. Moreover, they could construct mental objects of a constant rate of change, understanding the situation where the relationship between time difference and distance difference becomes one value, namely speed. The students had difficulties in connecting the rate of change with the inclination of a line. The students constructed the essence (concept) of linear functions, after building and organizing the image that the rate of change is constant, the graph is linear, and the equation is formulated as y=ax+b (a: inclination, b: intercept).

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.65.2-65.2
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• 2005

• Communications of the Korean Mathematical Society
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• v.35 no.1
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• pp.321-338
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• 2020

In this paper, we investigate the viscoelastic plate equation with a constant delay term and logarithmic nonlinearities. Under some conditions, we will prove the global existence. Furthermore, we use weighted spaces to establish a general decay rate of solution.

• Journal of Chest Surgery
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• v.6 no.1
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• pp.15-22
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• 1973

The definition of cancer, its diagnosis and its prognosis all depend upon description of growth. To the layman a synonym for cancer is a "growth". There are no quantitative terms for the description of growth or growth rate in clinical use. There has been no attempt to assign values that would define "rapidly" or "slowly" growing. Estimates of growth potentiality are implied in the descriptive phrases "poorly differentiated" or "well differentiated", "highly malignant" or "low grade malignancy". and in systems of grading. These qualifying terms represent a personal impression, clinically useful in prognosis, but relative in nature. They do not lend themselves to uniform application or precise measurement for purpose of comparison. Growth is related to size and time. The volume of tumor depends upon the duration of the period of growth and the rate of growth. If the interval and change in volume are known. the average growth rate can be determined. If the growth rate is determined, and assumed to be constant., the duration of a given tumor and the time of inception can be estimated. The commonest concept of the origin of cancer is that as a result of a mutation involving a single cell, succeeding divisions of cells establish a colony with the characteristics recognizable as cancer. If the growth rate of the hypothetical tumor were constant it could be described in terms of "tumor volume doubling time". In the department of thoracic surgery of St. Mary hospital in Catholic Medical College, a clinical evaluation for the growth rate, degree of malignancy, resectability and prognosis was done on a total 24 cases of primary bronchogenic carcinoma which contour was significant on the chest X-ray film as possible estimating the tumor volume doubling time. The following results were obtained: 1. In the cases of 6.0cm or more in diameter of minor size at operation the resectability rate was lower and in the cases of 60 days or more in the tumor or volume doubling time the resectability rate was higher. 2. If differentiation of cancer cells was lower graded in tissue pathology, the tumor volume was shorter and the resectability rate was lower. 3. The tumor volume doubling time of the primary bronchogenic carcinoma occured more over 60 years of age was slightly shorter than under 60 years of age. 4. The tumor size at operation was more important to evaluate the survival time and prognosis than the tumor volume doubling time because the tumor growth was not always constant, we presume.mor volume doubling time because the tumor growth was not always constant, we presume.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.1156-1167
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• 2010

The constant rate of strain (CRS) consolidation test has been widely used to evaluate consolidation characteristics of soils instead of the standard Incremental Loading Test. In practical problems, after the ground improvement, the condition of the soil is over-consolidated. Therefore, it is important to determine the recompression indices and the coefficient of consolidation(or the coefficient of swelling) of unloading-reloading cycle to predict the settlement behavior. However, since standard testing procedures or studies related with strain rate are insufficient especially in unloading-reloading cycle, it is difficult to predict the settlement field behavior accurately from the CRS consolidation test results in spite of its lots of strengths. The several CRS consolidation tests were performed changing the unloading strain rate from 0.2%/hr to 20%/hr with vertical drainage condition using the reconstituted kaolinite sample. For the reconstituted kaolinite sample in CRS consolidation test, the recompression indices are insensitive to the strain rate. It is revealed that the coefficient of consolidation of reloading is affected by the developed pore pressure during unloading. Additionally, the test should be conducted in the positive pore pressure ratio range (3~15%) to obtain the reasonable coefficient of consolidation in the whole range(loading, unloading and reloading).

• Journal of Environmental Health Sciences
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• v.28 no.2
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• pp.183-192
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• 2002

Indoor air quality is affected by source strength of pollutants, ventilation rate, decay rate, outdoor level and so on. Although technologies exist to measure these factors directly, direct measurements of all factors are impractical in most field studies. The purpose of this study was to develop an alternative methods to estimate these factors by multiple measurements. Daily indoor and outdoor NO$_2$concentrations for 21 days in 20 houses in summer and winter, Seoul. Using a mass balance model and linear regression analysis, penetration factor (ventilation divided by sum of air exchange rate and deposition constant) and source strength factor(emission rate divided by sum of air exchange rate and deposition constant) were calculated. Subsequently, the ventilation and source strength were estimated. During sampling period, geometric mean of natural ventilation was estimated to be 1.10$\pm$1.53 ACH, assuming a residential NO$_2$decay rate of 0.8 hr$^{-1}$ in summer. In winter, natural ventilation was 0.75$\pm$1.31 ACH. And mean source strengths in summer and winter were 14.8ppb/hr and 22.4ppb/hr, respectively. Although the method showed similar finding previous studies, the study did not measure ACH or the source strength of the house directly. As validation of natural ventilations, infiltrations were measured with $CO_2$tracer gas in 18 houses. Relationship between ventilation and infiltration was statistically correlated (Pearson r=0.63, p=0.02).