• Analytical Science and Technology
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• v.24 no.6
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• pp.421-428
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• 2011

In this study, headspace disk type monolithic material sorptive extraction (HS-MMSE) was developed, validated and applied to the analysis of volatile aroma compounds from vanilla perfume by gas chromatography -mass spectrometry (GC/MS). HS-MMSE uses monolithic material (MonoTrap) based on silica bonded with octadecyl silane (ODS) and activated carbon as a sorbent. Aroma compounds was adsorbed onto the MonoTrap in headspace and extracted by only 100 ${\mu}L$ of solvent. Total 12 volatile compounds from vanilla perfume were successfully analyzed using HS-MMSE. The influence of extractive parameters was investigated and optimized, using benzyl acetate, linalyl acetate, vanillin, ethyl vanillin as target compounds. Under the optimum condition, the limit of detection (S/N = 3) and the limit of quantification (S/N = 10) of proposed method for the target compounds were obtained within the range of 8.35~13.76 ng and 27.82~45.88 ng, respectively. The method showed good linearity with correlation coefficient more than 0.9888, satisfactory recovery and reproducibility. These results showed that HS-MMSE using disk type MonoTrap is a new promising technique for the analysis of volatile aroma compounds from vanilla perfume.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2103-2108
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• 2017

For n points $p_i$ on the m-dimensional plane $R^m$ and a fixed range r, consider a set $T_i$ containing points the distances from $p_i$ of which are less than or equal to r. In case m=1, $T_i$ is an interval on a line, it is a circle on a plane when m=2. For the vertices corresponding to the sets $T_i$, there is an edge between the vertices if the two sets intersect. Then this graph is called an intersection graph G. For m=1 G is called a proper interval graph and for m=2, it is called an unit disk graph. In this paper, we are concerned in the intersection graph G(r) when r changes. In particular, we consider the problem to find the minimum r such that G(r)is connected. For this problem, we propose an O(n) algorithm for the proper interval graph and an $O(n^2{\log}\;n)$ algorithm for the unit disk graph. For the dynamic environment in which the points on a line are added or deleted, we give an O(log n) algorithm for the problem.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.2 no.2
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• pp.39-46
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• 1982

A model of substrate removal by rotating discs has been developed for a better understanding of the process, and the performance of the system has been evaluated under steady and unsteady state. The model was constructed based upon mass transfer of the substrate from the bulk solution to the biofilm and a simultaneous removal of the substrate by the biomass. The model is composed of a few sets of differential equations representing mass balance within the elements of a liquid film and a biofilm, and in the bulk solution. Substrate removal efficiency of the process is largely dependent on a diffusion coefficient of the substrate within the biofilm and a maximum rate of substrate removal of the biomass. The efficiency is affected to a greater extent when the substrate concentration is low and the maximum substrate removal rate is high. The efficiency increases proportionally with increasing film depth when the biofilm is shallow, however, the rate of increase gradually decreases with an increase of the film depth. As the film reaches a limiting depth, the efficiency remains constant. Unlike the steady state, the effluent quality is affected by the tank volume under dynamic state. Increasing tank volume decreases peak concentration of the effluent under peak loading. Additional tank volume provides a buffer capacitya.gainst a peak loading and the holding tank behaves like an equalization tank.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.3
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• pp.168-176
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• 2013

The aim of this study was to evaluate the acid neutralizing capacity and to observe surface changes of giomer in comparison with composite resin, when it comes in contact with an acidic solution. A packable giomer(Beautifil II) and a flowable giomer(Beautifil Flow F02) were used as experimental groups, while a packable composite resin($Filtek^{TM}$ Z-250) was used as control group. pH values were measured after mixing the specimens of the disc and powder types with a pH 2.0 hydrochloric acid solution, respectively. Also, in the case of powder type giomers used in the earlier experiment, their pH values were measured again after mixing them with a fresh acid solution. Moreover, surface structure changes of disc type specimens were observed by using a scanning electron microscopy(SEM). In the disc type test, the pH values of packable giomer were significantly increased after 24 hours(p < 0.05). In contrast, in the powder type test, the pH values of packable and flowable giomers were dramatically increased within 30 minutes. The pH value of packable giomer, in particular, was higer than that of flowable giomer(p < 0.05). In the repeated neutralizing test, the degree of pH variation was lower than that of the previous neutralizing test(p < 0.05). Erosive changes on the surface of packable giomer were observed to be more than those on composite resin and flowable giomer as well. In conclusion, giomer has a acid neutralizing capacity, when it comes in contact with an acidic solution. Especially, packable giomer with high filler content has a greater acid neutralizing capacity than flowable giomer.

• Journal of Oral Medicine and Pain
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• v.24 no.1
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• pp.25-36
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• 1999

저자는 이하두정방사선사진 (願下頭頂放射線寫眞, submentovertex radiographs)을 이용하여 하악과두의 수평각과 측두하악장애와의 연관성을 평가하고자 측두하악장애의 병력 및 증상이 없고, 자연치열로 형성된 정상교합을 가진 성인 34명과 전북대학교병원 구강내과에 내원한 측두하악장애환자 38명을 대상으로, 환자군을 임상검사 및 방사선학적 검사를 통해 편측 정복성 관절원판 전방변위 환자군, 양측 정복성 관절원판 전방변위 환자군 및 편측 비정복성 관절원판 전방변위 혹은 골관절염 환자군으로 세분한 후, 좌우측 외이도의 위치를 확인할 수 있도록 소강구 (小鋼球)가 내재된 장치물을 이용하여 채득한 규격화된 이하두정방사선사진상에서 하악과두의 내측극과 외측극을 이은 선과 양측 외이공에 위치한 소강구를 이은 선으로부터 하악과두의 수평각을 측정하였다. 평가 결과 정상군에서의 좌(평균 25.3도), 우(평균 24.8도)측 하악과두의 수평각 (평균 25.0도)은 유의한 차이를 보이지 않았으며 환자군에서는 이환측 하악과두의 수평각 (평균 28.5도)이 비이환측 하악과두 (평균 26.2도)보다 유의성있게 증가된 수치를 보였다 (p<0.05). 또한 환자군 (평균 27.55도)에서의 하악과두의 수평각이 정상군 (평균 25.0도)에서 보다 유의하게 증가된 수치를 보였다 (p<0.05). 임상적으로 세군으로 구분된 환자군의 경우, 각군의 이환측 또는 비이환측, 각 군을 합한 이환측 또는 비이환측의 경우에 있어서도 정상군에서 보다 하악과두 수평각이 유의성있게 증가된 수치를 보였다 (p<0.05). 세가지로 구분된 환자군 각각의 상호 비교에 있어서는 유의성있는 차이를 나타내지 않았다. 그리고 편측으로 이환된 환자군에서의 이환된 수평각 (평균 29.1도)은 비이환측 (평균 26.2도)보다 유의성있게 증가된 수치를 보였으나 (p<0.05), 양측으로 이환된 환자군에서의 좌우측 수평각은 유의한 차이를 보이지 않았다. 이로써 측두하악장애의 진단 차원에서 측두하악장애를 유발하는 여러 요소 중외 하나로 하악과두 수평각에 대한 평가가 고려되어야 할 것으로 사료된다.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.18 no.6
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• pp.563-570
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• 1985

The main purpose of this study is to evaluate a revolving plate-type biofilter system for mass culture of eels (Anguilla japonica) based on the experimental rearing for 199 days. Water quality, growth efficiency of fish and effects of fish disease control were critically evaluated. The experiment was conducted in two different units, each unit consisting of a cement tank containing $20m^3$ of water. In unit A, a biofilter which includes 400 rotating undulated P. V. C. plates being 70 cm in diameter which rotates at 6 rpm and also 400 undulated P. V. C. plates fixed in the settling chamber of an area of $66{\times}62cm$. Water was continuously passed through the filter at a rate of 260 l/min., and supplemental water was added to the fish tank at a rate of $4m^3$ a day. In unit B, the biofilter has 400 P. V. C. plates being $66{\times}62cm$ each was installed in the settling tank. The results gained from the experimental rearing for 199 days from April 21, 1984 to November 5, 1984 are as follows. In the growth experiment, the weight of fish in unit A increased from 3.0 kg to 815.6 kg, while in unit B, from 3.0kg to 416.0kg. During the period of the experiment, in the both units the fish grew at an acceptable rate at the temperature at which they were held. Observing every aspect of eel culture, including growth rate, disease control and water quality, unit A appears to have adventages over unit B, which makes it particuraly attractive in intensive recirculating fish culture system. It was further observed that certain parasites such as Trichodina sp. and Costia sp. could easily be controled by appling 4 ppm of $KMNO_4$.

• Journal of Oral Medicine and Pain
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• v.33 no.4
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• pp.387-394
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• 2008

Purpose : The purpose of this study was to verify the usefulness and feasibility of ultrasonographic imaging for the detection of the disorders of the surrounding supporting structure such as articular capsule, retrodiscal tissue and related ligaments, osteoarthritic evidence and associated disc displacement at the temporomandibular joint(TMJ) Materials and Methods : 20 patients(40 joints) with periodic lock and crepitations were investigated prospectively using 12 MHz array transducer. Ultrasonographic Imagings were assessed for osteoarthritic surface changes of condyle, extent of disc displacement and disorders of surrounding structures. Ultrasonographic images were compared with clinical investigations, conventional radiography and Dental Computed Tomographic scans. Results : In clinical and conventional radiography, osteoarthritic changes were diagnosed in 8 joints. Ultrasonographically 7 of the 8 osteoarthritic changes were diagnosed correctly. Sensitivity, specificity, and accuracy of ultrasonography in the osteoarthritic detections were 87.5%, 62.5%, and 67.5% respectively. About the detection of disc displacement, disc displacement were diagnosed in 21 joints clinically. Ultrasonographically 19 of the 21 disc displacements were diagnosed correctly. Sensitivity, specificity, and accuracy of ultrasonography in the osteoarthritic detections were 95%, 90%, and 92.5% respectively. when the disorders of supportive structure were figured out, the disorders of supportive structure were diagnosed in 18 joints clinically. Ultrasonographically 1 of the 18 the disorders of supportive structure were diagnosed correctly. Sensitivity, specificity, and accuracy of ultrasonography in the osteoarthritic detections were 5.5%, 4.5%, and 55% respectively. Conclusion : Ultrasonography is an relatively reliable diagnostic tool for the detection of disc displacement and some of osteoarthritic changes. But it's not an insufficient imaging technique for the detection of the disorders of the surrounding structure.

• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.52-59
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• 2015

Cross-cut disks from small diameter oak logs were thermally modified and developed to make accessories such as a brooch. However it is known that domestic oaks are refractory and it is hard to dry their cross-cut disks without any drying defects. The cross-cut disks of Quercus variabilis (7 mm long in the longitudinal direction) were forced to dry in air at two different air velocities in summer and fall season, and their drying yields were investigated. Under the same condition, the average final moisture contents (MCs) of the specimens dried in the fall were lower than those dried in the summer. The average final MCs of the small diameter specimens dried at higher air velocity were slightly lower than those at lower air velocity while those of the large diameter specimen were not influenced by the air velocity. The number of the large diameter specimens with cross checkings was higher than that of the small diameter specimen. This discrepancy between two different diameters was twice in the fall, while it was more than four times in the summer. The large diameter specimens dried at low air velocity in Summer were cross-checked most, which was attributed to repeated water condensation and evaporation due to high humidity and low air velocity.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.31 no.5
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• pp.622-630
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• 1998

Rotating Biological Contactor (RBC) was tested for the removal of total ammonia nitrogen (TAN) by using simulated aquaculture system. RBC performance was evaluated by controlling revolution rate of disk and hydraulic residence tile (HRT). The optimum revolution rate of disk was 4 rpm, As HRT of RBC was increased, TAN removal efficiency of RBC and TAN concentration of rearing water were increased. HRT for maintaining lowest TAN concentration of rearing water was 9.5 minutes and at that condition TAN concentration of rearing tank was $1.03 g/m^3$

• The Journal of the Petrological Society of Korea
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• v.24 no.2
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• pp.141-147
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• 2015

Using laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), we evaluated the reliability of trace element abundance data measured from the silicate rock references of JR-3, JG-3, JGb-1 and JB-1b using glass discs made by alkali fusion. For 28 elements including rare earth elements, relative standard deviations (RSD) are better than 7% in case when the concentrations of the elements in the rock samples are greater than 10 ppm. However, RSD shows somewhat increased values for the concentrations less than 10 ppm, but never exceeds 25%. Compared with previously reported averages of the compiled abundance data, our data display satisfactory results for the most cases with differences less than 10%. We suggest that LA-ICP-MS analysis using fused glass beads is a reliable, precise and time-saving method of trace element analysis for the silicate rocks spanning from mafic to felsic compositions.