• The Journal of Korean Academy of Prosthodontics
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• v.61 no.2
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• pp.160-178
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• 2023

Diagnosis and analysis of occlusal relationships are important factors in prosthetic treatment. A thorough occlusion analysis and evaluation should be performed before treatment to restore a stable interocclusal relationship. Analysis and evaluation are essential during the treatment process and at regular follow-ups. Recently, with the development of dental equipment and digital processing methods, new quantitative analysis methods that can record the patient's occlusal relationship have been introduced. Among them, the T-Scan Novus (Tekscan Inc., S. Boston, MA, USA) displays the strength of the initial contact point and the occlusal contact point of the teeth using a pressure sensor. With this, occlusal contact time of the teeth, anteroposterior and left-right balance of occlusal force can be compared. The Dental prescale II (GC Co., Tokyo, Japan) scans the occlusal contact point using a pressure-sensing film and analyzes the density of the contact point. It can measure the distribution and strength of the occlusal force of the teeth in the most natural occlusion state. Based on this, appropriate prosthetic treatment (four-unit fixed partial denture, removable partial denture, complete denture, and complete oral restoration cases) was performed according to the area and extent of the patient's tooth loss. The patient's occlusion at the first visit, treatment stage, right after treatment, and regular follow-up were compared and evaluated using a quantitative method for appropriate occlusion analysis using T-Scan Novus and Dental prescale II. This report enhances the understanding of occlusion analysis during prosthetic restoration. The results satisfied both the clinician and patients in terms of function and aesthetics.

• Journal of Environmental Science International
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• v.30 no.1
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• pp.45-55
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• 2021

In this study, the odor of the parts and the odor of the surrounding environment were classified and verified. In order to increase the reliability of odor quantitative/qualitative analysis, the selection criteria for 5 sensory evaluators were established, and the n-Butanol control solution for each odor intensity was periodically trained to recognize the odor intensity before sensory evaluation. In addition, although various odor thresholds have been used through several studies, verification of whether the odor intensity value obtained through GC/MSD analysis is similar to the degree to which a person directly smells and feels it. It is important to select the odor threshold that has the best correlation with the odor intensity calculated by the person smelling the odor. Finally, sampling and measuring flowing airflow and temporary odors such as odor component analysis was experimentally difficult due to limited collection space and differences in concentration of generated components. In this study, a quantitative analysis was made possible by using the low temperature concentration (cooling) trap method. Through this, it was confirmed that the correlation with the actual odor intensity was not caused by the product itself, but by the environmental factor discharged from the product after creating the odor environment.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.189-193
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• 1997

Major separation for the active ingredients and structural identification were performed in order for qualitative and quantitative analysis on Ligustici rhizoma or Angelicae tenuissimae Radix as an oriental herbal medicine for anodyne. The structure, composition and contents of ingredients for essential oil were determined by means of GC/MS. Several Angelicae tenuissimae Radix harvested in Korea were extracted, which has shown the higher crude content compared to that from China. The major component in Angelcae tenuissimae Radix extract was found to be Z-ligustilide (70-80%), which is very different from that in Ligustici rhizoma of which major component is proven to be senkyunolide (39%) with GC/MS.

• Journal of Applied Biological Chemistry
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• v.44 no.3
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• pp.140-142
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• 2001

Quantitative gas chromatographic method for determining the ant repellent activity of cineol, ${\alpha}$-terpineol, linalool, and piperitone which usually found in Chinese Prickly Ash Zanthoxylum piperitum DC. was developed. These monoterpenes showed higher ant repellent activities than DEET due perhaps to their volatility. Gas chromatographic method quantified the volatility of the four monoterpenes and DEET.

• Clean Technology
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• v.17 no.1
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• pp.56-61
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• 2011

In this study, hydrocarcking of vacuum residue was carried out in an autoclave reactor at $450^{\circ}C$ and $500^{\circ}C$ with a commercial catalyst (HDM) and the quantitative product distributions were analyzed by GC-SIMDIS method or simple distillation. During catalytic hydrocracking, thermal cracking also occurred together with catalytic cracking and the higher conversion and selectivity of gasoline and naphtha were obtained at high reaction temperature. GC-SIMDIS and simple distillation revealed different results for the analysis of products produced at different hydrocracking temperatures; almost same results were obtained for the product produced at $500^{\circ}C$ but different ones for the product produced at $450^{\circ}C$. In the analysis of product produced at $450^{\circ}C$, the GC-SIMDIS showed that a main product was VGO while a main product in the simple distillation was diesel, which implies that the simple distillation for the $450^{\circ}C$ reaction was not accurate due to thermal cracking of the product by the simple distillation.

• Analytical Science and Technology
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• v.25 no.6
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• pp.395-401
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• 2012

This study presents a method for the quantitative analysis of residual vinyl chloride monomer (VCM) in PVC products. In elution solvent, the extraction efficiency was similar by ethanol, THF, and acetone, but using n-hexane, it indicated relatively low extraction efficiency. Measuring VCM in the pulverized PVC samples, it showed reasonable results in both the direct injection method and headspace method with GC/MS. Regarding analysis of VCM in the intermediate sponge samples, five laboratories showed good results, and from the results, it was considered that VCM quantitative method in this study was reliable.

• Animal cells and systems
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• v.12 no.3
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• pp.165-170
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• 2008

Cuticular hydrocarbons(CHCs) of the epicuticle wax layer are so far used to differentiate the insects in species and subspecies levels. In this study, four species of malaria vectors(genus Anopheles) were collected from various localities in southern Iran. Twenty specimens of each species were randomly selected and one epicuticular extract was prepared of every five specimens. FID-GC profiles of the extracts did not show any qualitative difference. Using significant difference of CHC mass at retention time(RT) 39.6, the two species of An. sacharovi and An. fluviatilis could be distinguished. Similarly, the two species of An. superpictus & An. sacharovi and An. dthali & An. sacharovi were differentiated by their CHC level at RT 28.5. An. sacharovi was distinguished by integratable peaks at RTs 29.7, 30.6, 30.7, 31 and 32.6 while the other three species just indicated trace peaks at the same RTs. Similarly, An. dthali could be known by an integratable peak at RT 26.2 while An. fluviatilis and An. superpictus indicated trace peaks at the same RT. Integratable peaks and traces at RTs 27.4 and 28.5 were respectively used to differentiate An. superpictus from An. fluviatilis. Lastly, CHC trace amount of An. superpictus at RT 39.6 is another indicator to distinguish it from An. fluviatilis with an integratable peak at the same RT. In harmony with other studies worldwide we hereby report that quantitative analysis of CHCs was successfully applied to differentiate the four Anopheles species of southern Iran.

• Analytical Science and Technology
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• v.30 no.4
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• pp.174-181
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• 2017

Bio-liquid is a liquid by-product of the hydrothermal carbonization (HTC) reaction, converting wet biomass into solid hydrochar, bio-liquid, and bio-gas. Since bio-liquid contains various compounds, it requires efficient sampling method to extract the target compounds from bio-liquid. In this research, fatty acid methyl ester (FAME) in bio-liquid was extracted based on hollow fiber supported liquid phase microextraction (HF-LPME) and determined by Gas Chromatography-Flame Ionization Detector (GC-FID) and Gas Chromatography/Mass Spectrometry (GC/MS). The well-known major components of biodiesel, including methyl myristate, palmitate, methyl palmitoleate, methyl stearate, methyl oleate, and methyl linoleate had been selected as standard materials for FAME analysis using HF-LPME. Physicochemical properties of bio-liquid was measured that the acidity was 3.30 (${\pm}0.01$) and the moisture content was 100.84 (${\pm}3.02$)%. The optimization of HF-LPME method had been investigated by varying the experimental parameters such as extraction solvent, extraction time, stirring speed, and the length of HF at the fixed concentration of NaCl salt. As a result, optimal conditions of HF-LPME for FAMEs were; n-octanol for extraction solvent, 30 min for extraction time, 1200 rpm for stirring speed, 20 mm for the HF length, and 0.5 w/v% for the concentration of NaCl. Validation of HF-LPME was performed with limit of detection (LOD), limit of quantitation (LOQ), dynamic range, reproducibility, and recovery. The results obtained from this study indicated that HF-LPME was suitable for the preconcentration method and the quantitative analysis to characterize FAMEs in bio-liquid generated from food waste via HTC reaction.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.32 no.4
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• pp.340-349
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• 2022

Objectives: The importance of MSDS is emphasized for communicating hazardous information due to the increase in the types and usage of chemical substances. The purpose of this study is to assess the reliability of MSDS by collecting and examining paint thinners commercially available in South Korea. Methods: Twenty-five paint thinners were purchased at paint stores and the provision of MSDS was checked. Quantitative and qualitative analysis was performed on the chemical constituents of the thinners using GC-MSD and GC-FID. Reliability was evaluated by the MSDS collection rate for the paint thinners and calculating the rate of matching between laboratory analysis results and the contents and composition of chemical constituents given in the MSDS. Results: Unlike a study conducted in 2006, MSDS were provided for all 25 thinners. As a result of qualitative analysis using GC-MSD, 104 chemical substances were detected. The substances with the highest detection rate were identified in the order of toluene, butyl acetate, acetone, xylene, and ethyl benzene. A component matching rate of 41% was found by comparing the differences between the number of substances detected in laboratory testing and the number of substances listed in the MSDS. Benzene, a carcinogen not listed in the MSDS, was detected in two thinners produced by a small company. The detected benzene contents were 0.039 and 0.040%. When benzene is used, it should be strictly handled according to the Industrial Safety and Health Act. However, since it is not listed on the MSDS, it is judged that benzene was not being managed as a carcinogen in the workplaces where it is used. Conclusions: Since the reliability of MSDS, which play an important role in hazard communication, was evaluated to be low, it is necessary to systematically and continuously secure this reliability. In particular, carcinogens should be managed more strictly.

• Journal of Pharmaceutical Investigation
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• v.40 no.3
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• pp.155-160
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• 2010

A gas chromatographic-mass spectrometric (GC-MS) method was developed for the simultaneous determination of valproic acid (VPA) and its toxic metabolites, 4-ene-VPA and 2,4-diene-VPA in rat plasma. Extraction was performed in weak acidic condition (pH 5.2) to avoid degradation of 4-ene-VPA and 2,4-diene-VPA. The recoveries for 4-ene-VPA and 2,4-diene-VPA were more than 70% and that for VPA was 33-42%. R value for each compounds exceeded 0.998 in calibration curve during all the analysis. Accuracy and precision ranged from 88.3 to 113.2% and from 2.16 to 14.2%, respectively The method was successfully applied to monitor plasma concentrations of VPA, 4-ene-VPA and 2,4-diene-VPA after intravenous administration of VPA at the dose of 100 mg/kg, suggesting that these toxic metabolites may involved in the hepatotoxicity induced by VPA.