• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.3
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• pp.233-244
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• 2014

Precise Point Positioning (PPP) is an increasingly recognized precisely the GPS/GNSS positioning technique. In order to improve the accuracy of PPP, the error sources in PPP measurements should be reduced as much as possible and the ambiguities should be correctly resolved. The correct ambiguity resolution requires a careful control of residual errors that are normally categorized into random and systematic errors. To understand effects from two categorized errors on the PPP ambiguity resolution, those two GPS datasets are simulated by generating in locations in South Korea (denoted as SUWN) and Hong Kong (PolyU). Both simulation cases are studied for each dataset; the first case is that all the satellites are affected by systematic and random errors, and the second case is that only a few satellites are affected. In the first case with random errors only, when the magnitude of random errors is increased, L1 ambiguities have a much higher chance to be incorrectly fixed. However, the size of ambiguity error is not exactly proportional to the magnitude of random error. Satellite geometry has more impacts on the L1 ambiguity resolution than the magnitude of random errors. In the first case when all the satellites have both random and systematic errors, the accuracy of fixed ambiguities is considerably affected by the systematic error. A pseudorange systematic error of 5 cm is the much more detrimental to ambiguity resolutions than carrier phase systematic error of 2 mm. In the $2^{nd}$ case when only a portion of satellites have systematic and random errors, the L1 ambiguity resolution in PPP can be still corrected. The number of allowable satellites varies from stations to stations, depending on the geometry of satellites. Through extensive simulation tests under different schemes, this paper sheds light on how the PPP ambiguity resolution (more precisely L1 ambiguity resolution) is affected by the characteristics of the residual errors in PPP observations. The numerical examples recall the PPP data analysts that how accurate the error correction models must achieve in order to get all the ambiguities resolved correctly.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.5
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• pp.599-605
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• 2009

Changes of atmospheric pressures cause short- and long-term crustal deformations and thus become error sources in the site positions estimated from space geodesy equipments. In this study, we computed daily displacements due to the atmospheric pressure loading (ATML) at the 14 permanent GPS sites operated by National Geographic Information Institute. And the 10-year GPS data collected at those stations were processed to create a continuous time series of the height estimate. Then, we corrected for the ATML from the GPS height time series to see if the correction changes the site velocity and improves the precision of the time series. While the precision improved by about 4% on average, the velocity change was not significant at all. We also investigated the overall characteristics of the ATML in the southern Korean peninsula by computing the ATML effects at the inland grid points with a $0.5^{\circ}{\times}0.5^{\circ}$ spatial resolution. We found that ATML displacements show annual signals and those signals can be fitted with sinusoidal functions. The amplitudes were in the range of 3-4 mm, and they were higher at higher latitudes and lower at the costal area.

• Journal of Biosystems Engineering
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• v.42 no.4
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• pp.350-357
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• 2017

Purpose: In-situ monitoring of water quality is fundamental to most environmental applications. The high cost and long delays of conventional laboratory methods used to determine water quality, including on-site sampling and chemical analysis, have limited their use in efficiently managing water sources while preventing environmental pollution. The objective of this study was to develop an on-site water monitoring system consisting mainly of an Arduino board and a sensor array of multiple ion selective electrodes (ISEs) to measure the concentration of $NO_3$ ions. Methods: The developed system includes a combination of three ISEs, double-junction reference electrode, solution container, sampling system consisting of three pumps and solenoid valves, signal processing circuit, and an Arduino board for data acquisition and system control. Prior to each sample measurement, a two-point normalization method was applied for a sensitivity adjustment followed by an offset adjustment to minimize the potential drift that could occur during continuous measurement and standardize the response of multiple electrodes. To investigate its utility in on-site nitrate monitoring, the prototype was tested in a facility where drinking water was collected from a water supply source. Results: Differences in the electric potentials of the $NO_3$ ISEs between 10 and $100mg{\cdot}L^{-1}$ $NO_3$ concentration levels were nearly constant with negative sensitivities of 58 to 62 mV during the period of sample measurement, which is representative of a stable electrode response. The $NO_3$ concentrations determined by the ISEs were almost comparable to those obtained with standard instruments within 15% relative errors. Conclusions: The use of the developed on-site nitrate monitoring system based on automatic sampling and two-point normalization was feasible for detecting abrupt changes in nitrate concentration at various water supply sites, showing a maximum difference of $4.2mg{\cdot}L^{-1}$ from an actual concentration of $14mg{\cdot}L^{-1}$.

• Applied Biological Chemistry
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• v.49 no.2
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• pp.140-144
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• 2006

Sajabalssuk (Artemisia herba) was extracted with 80% aqueous MeOH, and the concentrated extract was partitioned with EtOAc, n-BuOH and $H_2O$, successively. From the EtOAc and n-BuOH fractions, four sterols were isolated through the repeated silica gel and ODS column chromatographies. From the results of physico-chemical data including NMR, MS and IR, the chemical structures of the sterols were determined as ${\beta}-sitosterol$ (1), ergosterol peroxide (2), stigmasterol (3) and daucosterol (4). They were the first to be isolated from Sajabalssuk (Artemisia herba).

• Economic and Environmental Geology
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• v.43 no.1
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• pp.43-52
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• 2010

The geochemical and nitrogen isotopic analyses for shallow groundwater of Ogcheon area were carried out to characterize the geochemical characteristics of the groundwater and to identify the source of nitrate. Groundwater shows a neutral pH to weakly alkalic condition with pH values ranging from 6.9 to 8.4. The average of EC, Eh and DO is $344.2\;{\mu}s/cm$, 195 mV, 4 mg/L, respectively. According to piper diagram, chemical composition of groundwater is dominantly characterized by Ca-$HCO_3$ type. On the other hand, groundwater type in the study area include Ca-Cl+$NO_3$ type that were highly influenced by agricultural activities. $NO_3$-N concentration of the collected samples(n=45) range from 12.4 to 34.2 mg/l. These data show that the $NO_3$-N concentration exceeds Korea Drinking Water Standard (10 mg/l). The $\delta^{15}N-NO_3$ values range from $2.7^{\circ}/_{\circ\circ}$ to $18.8^{\circ}/_{\circ\circ}$. The enrichments of heavy isotope in the groundwater indicate that major origin of nitrate pollution were associated with animal and human waste. Also the denitrification may have partly contributed as one of the sources of nitrogen.

• Journal of the Korean Society of Food Culture
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• v.5 no.3
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• pp.331-347
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• 1990

This study was designed under the purpose to analyze the Korean Traditional Folk Remedies on food, to submit the basic statistical data, and to utilize them by examining how much they know about the Korean Traditional Folk Remedies and also by examining how frequently they used them. The sample was consisted of 312 housewives living in Daegu, Kyungsan city and Kyungsan-eup, the survey was made by use of questionaires from July 15 to August 1 1989. The results are as follows 1. Analysis of Folk Remedical Contents 1) The method of the Folk Remedies used in this area was mainly food, which can be easily found around their house and easy to use, it was possible to apply scientific principles in some cases. 2) The major popular method was shown to feed boiled barley or brown rice which are known as the Folk Remedy for Diabetes. 3) The ANOVA of variable shows the significant influence on each object which age, religion, the level of education, job, monthly income, and the area except family formation. 2. The Frequency of Folk Remedies and additional analysis 1) The most frequently used Folk Remedy was Arterio-sclerosis(1.44), which is followed by the loss of Eyesight(1.40), Hang over(1.28), Couth(1.27), Cold(1.26) etc. 2) In the analysis of Pearson Correlation between frequencies of Folk Remedies used, and demographic variables such as age(p<.05), the monthly income(p<.01), in that area, total number of response items showed a positive correlation. 3. The source to learn about Folk Remedy. 1) It is acknoledged that they are mostly instructed by their forefathers, friends, neighbors, professional textbooks, mass communications, herb doctors, other medical sources or education at school etc. 2) The ANOVA of Variables shows the big differences between each group by age. Based on the above findings, the following suggestions are made ; Most of Korean Traditional Folk Remedies are recognized scientific and reasonable which are based on the scientific research and herb medicine therefore it should be made good use of for our life in good health additionally. I hereby insist that the importance of our Folk Remedies should be reviewed and focused for maintenance our health.

• Journal of KIISE:Software and Applications
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• v.34 no.3
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• pp.226-234
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• 2007

In this paper, we develop a speech recognition system using a throat microphone. The use of this kind of microphone minimizes the impact of environmental noise. However, because of the absence of high frequencies and the partially loss of formant frequencies, previous systems developed with those devices have shown a lower recognition rate than systems which use standard microphone signals. This problem has led to researchers using throat microphone signals as supplementary data sources supporting standard microphone signals. In this paper, we present a high performance ASR system which we developed using only a throat microphone by taking advantage of Korean Phonological Feature Theory and a detailed throat signal analysis. Analyzing the spectrum and the result of FFT of the throat microphone signal, we find that the conventional MFCC feature vector that uses a critical pass filter does not characterize the throat microphone signals well. We also describe the conditions of the feature extraction algorithm which make it best suited for throat microphone signal analysis. The conditions involve (1) a sensitive band-pass filter and (2) use of feature vector which is suitable for voice/non-voice classification. We experimentally show that the ZCPA algorithm designed to meet these conditions improves the recognizer's performance by approximately 16%. And we find that an additional noise-canceling algorithm such as RAST A results in 2% more performance improvement.

• Journal of Biosystems Engineering
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• v.3 no.2
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• pp.100-113
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• 1978

Drying grain with conventional artificial drying methods requires great quantities of petroleum fuels. Depletion of fossil fuel increases the need of the utilization of solar energy as an alternative to petroluem fuels for drying grain , an energy intensive agricultural operation. Many techniques for the utilization of solar energy in grain drying have been developed, however, there are many problems in adopting solar energy as an energy sources for drying grain. Futhermore, very little research has been done on solar grain drying in Korea. This study was conducted to evaluate the availability of solar energy for drying of rough rice in Chuncheon, Suweon, and Jinju areas based on 50year meteorological data, and to analyze experimentally the performance of a solar air collector for dying grain, and to find the effects of solar heated air compared to unheated air on the rate of drying and energy consumption required for drying of rough rice. The results of this study was may be summarized as follows ; 1. Monthly average daily total radiation on a horizontal surface in October was 260.6 ly/day for Chuncheon, 240.3 ly/day for Suweon , and 253.4 ly/day for Jinju area, respectively. 2. the ratio of monthly average daily diffuse radiation to daily total radiation on a horizontal surface was approximately 0.41 for Chuncheon, 0.45 for Suweon, and 0.44 for Jinju area, respectively. 3. Although the statistical distribution curves of daily total radiation for the three locations were not identical , the differences among them were not large and may be neglected for many practical purposes. 4. I was estimated that the optimum tilting angle of the collector in October was approximately 46 degrees for Chuncheon and Suweon and 45 degrees for Jinju. 5. The ratio of the total radiation on a optimum tilting plane to that on a horizontal plane was estimated to be 1.36 for Chuncheon, 1.31 for Suweon, and 1.27 for Jinju , respectively. 6. The collection efficiency of the solar air collector ranged from 47. 8 to 51. 5 percent at the air flow rates of 251. 1-372.96 $m^3$/hr. High efficiency remained nearly , constant during the best sunshine hours, 10 a.m. to 2 p.m. and decreased during other hours. More energy was collected as the air flow rate incresed. 7. The average temperature rise in the drying air from the solar collector for the test period varied from $6.5^\circC$ to $21.8^\circC$ above the ambient air temperature. 8. Solar-dried rough rice averaged 13.7 percent moisture (w.b.) after 130 hours of drying with the air flow rate of 1. 64 ccm/$m^3$, and rough rice dried with natural air averaged 15.1 percent moisture (w.b.) after 325 hours of drying with the same air flow rate. 9. Energy saving of 2.4 kwh per $m^3$ percentage point of moisture removed was obtained from solar heated air drYing. The solar bin used 53.3 percent less energy per percentage point of moisture removed than the natural air bin.

• Health Policy and Management
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• v.10 no.1
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• pp.111-125
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• 2000

To compare the differences in the recognition on hospital utilization and satisfaction, 368 hospital employees and 485 patients were selected in four hospitals in Seoul and Kyung-gi do. The survey was done using a constructed form of checklist from Apr. 30 to May 10, 1999. And the results are as follows: l. Gaining knowledge of hospitals available among hospital employees differed from that of patients. When finding out about sources of information concerning hospitals, direct visit to the hospital was recognized to be the main factor for the hospital employees in contrast to the patients' recognition which were mass media, personal involvement of job related workplace and recommendations from other hospitals. There was no difference between university and general hospitals. 2. The factors that concern which hospital to choose there was a difference between hospital employees and patients. Hospital employees recommended their own hospital solely based on the reason that it was their work place. On the other hand, the patients made a choice based on the type of medical staff, transportation available and whether it was a university hospital or not. There was no difference between university and general hospitals. 3. The recognition of employees concerning hospital image of a hospital between hospital employees and patients was different. In university hospitals, the employees recognized the name value of university hospital and cooperation as most important, whereas the patients thought convenience, kindness were the main factors. Patients considered general hospitals to be more convenient. There was some difference between university and general hospitals. For university hospitals employees' recognition was higher and for the general hospital patients' recognition is higher on hospital image. 4. The recognition of employees was different from that of patients' on hospital satisfaction. The patients' satisfaction was higher than that of employees'. There was no difference between university and general hospitals. Based on the above findings, the employees' recognition on hospital utilization and satisfaction was different from that of the patients, but there was no difference between university and general hospitals. In both groups choice of hospital was associated with satisfaction. Results showing difference between employees' and patients' recognition can be applied to implement customer-oriented attitude and be used as a baseline data for internal-external marketing planning of hospital management. The study may be limited in that the results cannot be generalized due to its small sample size and not being able to reflect demographic variables and life style. Further studies to investigate the difference of hospital utilization and hospital satisfaction will be necessary to define demographic characteristics and recognition of employees which influences patients' hospital satisfaction.

• Journal of the Korean Society of Food Culture
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• v.7 no.1
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• pp.73-79
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• 1992

Food consumption pattern between Korea and Japan were compared on the basis of the data from the National Nutrition survey which has been carried out annually in Korea (1969-1988) and in Japan (1950-1988) for the guide of the future food and nutrition policy. Total food intake has been decreased in Japan since 1973. In spite of fluctation of total food intake, there was an increase of food consumption in Korea. The intake of animal food has been increased, while that of vegetable food decreased, in both countries. Proportion of the total food intake from animal sources of Japanese in 1988, 25.3%, was greater than that of Koreans, 20%. The intakes of cereal and grain products have been decreased in both countries, but the amount of these food groups consumed by Koreans was 70 to 80g more than that by Japanese in 1988. When the animal food intake was compared, intakes of meats, fishes, shellfish and eggs have been increased considerably in Korea. Intakes of milk and milk products and meat have been increased, while those of fishes, shellfishes and eggs kept an even level since 1975, in Japan. According to changes of the national standards of height and weight in both countries, the average height has been increased greatly from 1970 to 1980 in Korea, and the tendency was the same for the average weight.