• Journal of Korean Society on Water Environment
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• v.22 no.3
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• pp.534-539
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• 2006

The supply of oxygen for aeration is the largest energy consumer at activated sludge wastewater treatment plants. Replacement of less efficient aeration systems with fine pore aeration devices can save up to 50 percent of aeration energy costs. The purpose of this study was the diagnosis and evaluation of a domestic wastewater aeration system by the off-gas method which had been studied by US EPA and ASCE. For this study, an off-gas analyzer and its hood were made to collect off-gas. Also, a vacuum pump was connected to the analyzer to make suction of off-gas. Experiments were conducted at a domestic activated sludge wastewater treatment plant which had a single spiral roll aeration system installed with P.E tube diffuser. Data on OTE(f), SOTE(pw), OUR, and air flow rate were obtained from these experiments. In case of replacing an aeration system, it is recommended that it should be replaced with perforated membrane disc or ceramic disc fine bubble diffusers installed in a full floor coverage or grid pattern.

• Journal of the Semiconductor & Display Technology
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• v.21 no.2
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• pp.123-126
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• 2022

We investigated deep levels in n-type 4H-SiC epitaxy layer of the Positive-Intrinsic-Negative diode and Schottky barrier diodes by using deep level transient spectroscopy. Despite the excellent performance of 4H-SiC, research on various deep level defects still requires a lot of research to improve device performance. In Positive-Intrinsic-Negative diode, two defects of 196K and 628K are observed more than Schottky barrier diode. This is related to the action of impurity atoms infiltrating or occupying the 4H-SiC lattice in the ion implantation process. The I-V characteristics of the Positive-Intrinsic-Negative diode shows about ~100 times lower the leakage current level than Schottky barrier diode due to the grid structures in Positive-Intrinsic-Negative. As a result of comparing the capacitance of devices diode and Schottky barrier diode devices, it can be seen that the capacitance value lowered if it exists the P implantation regions from C-V characteristics.

• Journal of the Korean Association of Geographic Information Studies
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• v.19 no.1
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• pp.154-166
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• 2016

This study aims to contribute to better understanding the effects of the changes in the parameter values of GroundFilter algorithm(GF), which performs filtering process, and of GridsurfaceCreate algorithm(GC), which creates regular grid, provided in Fusion software on the accuracy of elevation of the final LiDAR-DEM products through comparative analysis. In order to test whether there are significant effects on the accuracy of the final LiDAR-DEM products due to the changes of GF(1, 3, 5, 7, 9) parameter levels and GC(1, 3, 5, 7, 9) parameter levels, two-way ANOVA is conducted based on residuals. The residuals are calculated using the differences between each sample plot's paired field-measured and DEM-derived elevation values given each individual GF and GC level. After that, Tukey HSD test is conducted as a post hoc test for grouping the levels. As a result of two-way ANOVA test, it is found that the change in the GF levels significantly affects the accuracy of LiDAR-DEM elevations(F-value : 27.340, p < 0.01), while the change in the GC levels does not significantly affect the accuracy of LiDAR-DEM elevations(F-value : 0.457). It is also found that the interaction effect between GF and GC levels is not likely to exist(F-value : 0.247). From the results of the Tukey HSD test in the GF levels, GF levels can be divided into two groups('7', '5', '9', '3' vs '1') by the differences of means of residuals. Given the current conditions, LiDAR-DEM can achieve the best accuracy when the level '7' and '3' are given as GF and GC level, respectively.

• The Journal of Korean Academy of Prosthodontics
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• v.41 no.6
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• pp.732-746
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• 2003

Statement of problem. Soft lining materials, also referred to as tissue conditioning materials, tissue heating materials, relining materials, soft liners or tissue conditioners, were first introduced to dentistry by a plastic manufacturer in 1959. Since the introduction of the materials to the dental field, their material properties have been continually improved through the effort of many researchers. Soft lining materials have become widely accepted, particularly by prosthodontists, because of their numerous clinical advantages and ease of manipulation. Unfortunately, few reports have been issued upon the topic of increasing the bond strength between the base metal alloy used in cast denture bases and PMMA soft liner modified with 4-META, nor upon the pattern of debonding and material change in wet environment like a intra oral situation. Purpose. The purposes of this study were comparing the bond strength between base metal alloy used for the cast denture bases and PMMA soft liner modified with 4-META, and describing the pattern of debonding and material property change in wet environment like the intraoral situation. Material and Methods. This study consisted of four experiments: 1. The in vitro measurement of shear bond strength of the adhesive soft liner. 2. The in vitro measurement of shear bond strength of the adhesive soft liner after 2 weeks of aging. 3. A comparison of debonding patterns. 4. An evaluation the Relation time of modified soft liner. The soft liner used in this study was commercially available as Coe-soft (GC America.IL.,USA), which is provided in forms of powder and liquid. This is a PMMA soft liner commonly used in dental clinics. The metal primer used in this study was 4-META containing primer packed in Meta fast denture base resin (Sun Medical Co., Osaka, Japan). The specimens were formed in a single lap joint desist which is useful for evaluating the apparent shear bond strength of adhesively bonded metal plate by tensile loading. Using the $20{\times}20mm$ transparent grid, percent area of adhesive soft liner remaining on the shear area was calculated to classify the debonding patterns. To evaluate the change of the initial flow of the modified adhesive soft liner, the gelation time was measured with an oscillating rheometer (Haake RS150W/ TC50, Haake Co., Germany). It was a stress control and parallel plate type with the diameter of 35mm. Conclusion. Within the conditions and limitations of this study, the following conclusions were drawn as follows. 1. There was significant increase of bond strength in the 5% 4-META, 10% 4-META containing groups and in the primer coated groups versus the control group(P<0.05). 2. After 2 weeks of aging, no significant increase in bond strength was found except for the group containing 10% 4-META (P<0.05). 3. The gelation times of the modified soft liner were 9.3 minutes for the 5% 4-META containing liner and 11.5 minutes for the 10% 4-META liner. 4. The debonding patterns of the 4-META containing group after 2 weeks of aging were similar to those of immediaely after preparation, but the debonding pattern of the primer group showed more adhesive failure after 2 weeks of aging.

• Economic and Environmental Geology
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• v.31 no.2
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• pp.127-139
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• 1998

A new technique of simultaneous inversion for 3-D seismic velocity structure by using direct, reflected, and refracted waves is applied to the southeast part of the Korean Peninsula including Pohang Basin, Kyongsang Basin and Ryongnam Massif. Pg, Sg, PmP, SmS, Pn, and Sn arrival times of 44 events with 554 seismic rays are inverted for locations and crustal structure. $6{\times}6$ with $0.5^{\circ}$ and 8 layers (4 km each layer) model was inverted. 3-D seismic crustal velocity tomography including eight sections from surface to Moho, ten profiles along latitude and longitude are analyzed. The results are as follows: 1) the average velocity and thickness of sediment are 5.04 km/s and 3-4 km, and the velocity of basement is 6.11 km/s. The shape of velocity in shallower layer is agreement with Bouguer gravity anomaly (Cho et al., 1997). 2) the velocities fluctuate strongly in the upper crust. The velocity distribution of the lower crust under Conrad appears basically horizontal. 3) the average depth of Moho is 30.4 km, and velocity is 8.01 km/s. 4) from the velocity and depth of the sediment, the thickness, velocity and form of the upper crust, and the depth and form of Moho, we can find the obvious differences among Ryongnam Massif, Kyongsang Basin and Pohang Basin. 5) the deep faults (a Ulsan series faults) near Kyongju and Pohang areas can be found to be normal and/or thrust faults with detachment extended to the bottom of the upper crust.

• Journal of the Korean Society of Food Science and Nutrition
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• v.41 no.2
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• pp.270-277
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• 2012

The purpose of this study was to evaluate the importance and satisfaction level foreigners place on human and physical evidence service in Korean restaurants based on nationality such as American/European, Japanese, Chinese, and Southeast Asian. The research was performed by using questionnaires conducted from August to September on 365 foreigners living in Busan. Total mean scores for the importance (3.96/5.00) and satisfaction (3.33/5.00) of Korean restaurant human and physical evidence service were significantly different (p<0.01), as the gap was -0.63. The mean scores of the gap were -1.03 for cleanliness of dining area, -1.01 for cleanliness of tableware, and -0.95 for easily understandable menu board. The mean scores of satisfaction for Southeast Asian individuals (3.77) were significantly (p<0.01) higher than those of American/European (3.40), Chinese (3.37), and Japanese (2.81). The importance and satisfaction grid showed that an easily understandable menu board and a brief description of the food or menu scored high for the importance and low for the satisfaction in American/European, Chinese, and Japanese individuals. Cleanliness of the dining area, cleanliness of tableware, cleanliness of staff appearance, kindness of employees, rapid resolution of complaints, and prompt and quick service scored high for importance and low for satisfaction in Japanese. However, Southeast Asians were satisfied with human and physical evidence service of Korean restaurants.

• Korean Journal of Remote Sensing
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• v.31 no.5
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• pp.449-459
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• 2015

The conventional National Forest Inventory(NFI)-based forest carbon stock estimation method is suitable for national-scale estimation, but is not for regional-scale estimation due to the lack of NFI plots. In this study, for the purpose of regional-scale carbon stock estimation, we created grid-based forest carbon stock maps using spatial ancillary data and two types of up-scaling methods. Chungnam province was chosen to represent the study area and for which the $5^{th}$ NFI (2006~2009) data was collected. The first method (method 1) selects forest type map as ancillary data and uses regression model for forest carbon stock estimation, whereas the second method (method 2) uses satellite imagery and k-Nearest Neighbor(k-NN) algorithm. Additionally, in order to consider uncertainty effects, the final AGB carbon stock maps were generated by performing 200 iterative processes with Monte Carlo simulation. As a result, compared to the NFI-based estimation(21,136,911 tonC), the total carbon stock was over-estimated by method 1(22,948,151 tonC), but was under-estimated by method 2(19,750,315 tonC). In the paired T-test with 186 independent data, the average carbon stock estimation by the NFI-based method was statistically different from method2(p<0.01), but was not different from method1(p>0.01). In particular, by means of Monte Carlo simulation, it was found that the smoothing effect of k-NN algorithm and mis-registration error between NFI plots and satellite image can lead to large uncertainty in carbon stock estimation. Although method 1 was found suitable for carbon stock estimation of forest stands that feature heterogeneous trees in Korea, satellite-based method is still in demand to provide periodic estimates of un-investigated, large forest area. In these respects, future work will focus on spatial and temporal extent of study area and robust carbon stock estimation with various satellite images and estimation methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.12
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• pp.1920-1928
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• 2014

The purpose of this study was to evaluate the importance and performance of middle school foodservice hygiene in Busan. In this study, questionnaires were administered to 1,000 students consisting of 100 students in 10 middle schools in Busan in December, 2013. The students assessed importance and performance of personal hygiene as 3.81 and 3.60 on a scale of 5.00, respectively. Males gave higher scores to importance and performance of personal hygienic than females. First grade students gave significantly higher scores than 2nd and 3rd grade students to importance and performance of personal hygienic. The mean scores of importance of foodservice hygiene were 4.47 for food hygiene, 4.25 for equipment hygiene, 4.23 for employee hygiene, and 4.19 for environment hygiene. For importance of foodservice hygiene, females gave significantly (P<0.001) higher scores than males. However, male gave significantly higher scores than females for performance of foodservice hygiene. The importance and performance grid showed important factors for personal and foodservice hygiene. 'Hand washing before eating the meal' for personal hygiene and 'cleanliness of tray' for foodservice hygiene showed the highest importance and lowest performance scores. Foodservice hygiene can be improved through customized education of students regarding meal service and food hygiene, equipment hygiene, and environment hygiene.

• Journal of the korean academy of Pediatric Dentistry
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• v.37 no.1
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• pp.1-12
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• 2010

The aim of this study was to evaluate the preventive effect of commercially available anticariogenic products, specifically, the tooth cream containing Casein phosphopeptide-amorphous calcium phosphate(CPP-ACP), fluoride varnish and low-level fluoride mouthrinse on enamel erosion induced by carbonated beverage in a short period of time. Enamel specimens were treated as follows and were then kept in artificial saliva for 24 hours followed by further processing by alternately soaking them in Cola beverage and in distilled water for 1 minute each five times. Group 1: control group (no treatment) Group 2: tooth cream with CPP-ACP Group 3: fluoride varnish (1,000 ppm F) Group 4: low-level fluoride mouthrinse (227 ppm F) Group 5: fluoride varnish + tooth cream with CPP-ACP Group 6: low-level fluoride mouthrinse + tooth cream with CPP-ACP Microhardness and erosion depth were measured and the mineral loss of each specimen was evaluated by measuring the volumetric fluorescence change(${\Delta}Q$) against the stable fluorescent grid using quantitative light-induced fluorescence(QLF). The experiment lasted for 6 days repeated each day. The results were as follows: 1. The microhardness was increased as follows: Group $1{\leq}2{\leq}4$<6<$3{\fallingdotseq}5$. 2. The mean erosion depth was increased as follows: Group $5{\fallingdotseq}3$<6<$4{\fallingdotseq}2{\fallingdotseq}1$. 3. The ${\Delta}Q$ was increased as follows: Group $1{\fallingdotseq}2{\leq}4{\leq}6{\leq}3{\fallingdotseq}5$. The decrement of ${\Delta}Q$ was similar between group 1 and 2, group 4 and 6 and group 3 and 5. 4. The ${\Delta}Q$ showed positive correlation with microhardness (r=0.96, p<0.05), while it was negatively correlated to erosion depth (r=-0.96, p<0.05).

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.9
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• pp.1414-1426
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• 2005

The evaluation of students and employees on the importance and the performance for sanitary characteristics in high school foodservices, was investigated. The questionnaires were administered to 379 students and 141 employees in 13 high school, in Busan and then the data evaluated by 5 scales method of Likert were statistically analyzed. The mean scores of the importance and the performance evaluated by students (4.26/3.24) were significantly (p<0.01) lower than those by employees (4.71/4.51). Both the students and the employees percepted that, among sanitary characteristics, cleanliness of meals was most important. The student assessed the performance of withdrawal of plate waste as lowest scores, however the employees assessed student's hygiene as lowest scores, among sanitary characteristics. The gap score of the student (-1.02) between the importance and performance for sanitary factor was higher than that of the employees (-0.02) in high school foodservice. The importance grid of students and employees revealed that the items of tray cleanliness, dining table cleanliness, restaurant cleanliness, and handwashing before serving were high scores to the students, but low scores to the employees. The performance grid of students and employees revealed that the items of tray cleanliness, dining table cleanliness, restaurant cleanliness, the sanitation of treatment process of Plate waste, cleanliness of utensils of platewaste, not touch utensils before serving, handwashing before serving, handwashing before eating and not touch inside of tray were low scores to both the students and the employees. Therefore, it is suggested that the sanitary operations for dining place, treatment process of plate waste and the student's hygiene might have to increase in high school foodservice.