• Journal of Biomedical Engineering Research
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• v.24 no.2
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• pp.69-75
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• 2003

Virtual colonoscopy is one of the Powerful tool for non-invasive colon examination and many in-vitro and in-vivo studies have shown its accuracy in Polyp or adenoma detection. But most of virtual colonoscopy requires high quality workstation and software and its cost is high to setup whole system. We developed PC-based 3D model creation and navigation program which has diverse functions. It can be easily installed to PC and connected to network system. The performance. when used as a virtual colonoscopy. is evaluated by calculating sensitivity of detection for the simulated polyp which is artificially made inside the Pig's colon and checked its clinical feasibility, Its total sensitivity is 76%. Grouping according to Polyps diameter, the sensitivity for detection of polyps 10 ㎜ or larger was 100%(40 of 40); 5.0-9.9 ㎜, 90.0(90 of 100): and smaller then 5 ㎜. 36.7%(22 of 60).

• Proceedings of the KIEE Conference
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• 2006.10c
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• pp.190-192
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• 2006

The clinical characteristics of photodamaged skin, such as coarse and fine wrinkle are not accurately evaluable with previous methods. Public awareness for wrinkle treatment and prevention which rely on proper assessment and evaluation of the underlying skin changes has been increased as the population ages. In this paper, we suggest an in-vivo method and instrument that allow us to acquire a wrinkle-enhanced image to improve the accuracy of quantitative and qualitative analysis for skin wrinkle. The method used involved white LED illumination and photography through polarizing filters. Finally, the polarized light photography yields an accurate and evaluable parameter of photodamaged skin, especially fine and coarse wrinkle.

• YAKHAK HOEJI
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• v.57 no.3
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• pp.226-233
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• 2013

Although the dissolution test can serve as an effective tool for quality control and predictor of in vivo performance, there are a number of drugs with no established dissolution specification in Korean Pharmaceutical Codex (KPC). So, with each reference and test drugs, the dissolution test method and an analytical procedure by HPLC were developed and validated to establish dissolution specification for acebrophylline capsules and bromhexine hydrochloride tablets. The dissolution condition was determined based on the "Guidelines on Specifications of Dissolution tests for Oral dosage forms" of Ministry of Food and Drug Safety (MFDS). The analytical method of HPLC was validated in specificity, linearity, precision and accuracy. Final dissolution test was performed with commercially available samples of 3 lots to establish specification. In addition, no difference was observed by the inter-laboratory evaluation. Dissolution specifications and conditions will be used for revising the monograph of acebrophylline capsules and bromhexine hydrochloride tablets in next supplement of KPC.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.5
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• pp.687-695
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• 2007

Statement of problem: The proper contact relation between adjacent teeth in each arch plays an important role in the stability and maintenance of the integrity of the dental arches. Proximal contact has been defined as the area of a tooth that is in close association, connection, or touch with an adjacent tooth in the same arch. Purpose: The aim of this study was to develop a digital device for measuring the proximal tooth contact tightness by pulling a thin stainless steel strip (2mm wide, 0.03mm thick) inserted between proximal tooth contact. Material and method: This device consists of measuring part, sensor part, motor part and body part. The stainless steel strip was connected to a stain gauge. The strain gauge was designed to convert the frictional force into a compressive force. This compressive force was detected as a electrical signal and the electrical signal was digitalized by a A/D converter. The digital signals were displayed by a micro-processor. The pulling speed was 8mm/s. Results: For testing reliability of the device in vivo, two healthy young adults (A, B) participated in this experiment. The tightness of proximal tooth contact between the second premolar and the first molar of mandible (subject A) and maxilla (subject B) was measured fifteen times for three days at rest. We double-checked the accuracy of the device with a Universal Testing Machine. Output signals from the Universal Testing Machine and the measuring device were compared. Regression analysis showed high linearity between these two signals. In vivo test, no significant differences were found between measurements. Conclusion: This device has shown to he capable of producing reliable and reproducible results in measuring proximal tooth contact. Therefore, it was considered that this device was appropriate to apply clinically.

• The Journal of the Acoustical Society of Korea
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• v.37 no.4
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• pp.215-222
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• 2018

This paper reports the development and performance evaluation of a backend system for real-time IVUS (Intravascular Ultrasound) imaging. The developed backend system was designed to minimize the amount of logic and memory usage by means of efficient LUTs (Look-up Tables), and it was implemented in a single FPGA (Field Programmable Gate Array) without using external memory. This makes it possible to implement the backend system that is less expensive, smaller, and lighter. The accuracy of the backend system implemented was evaluated by comparing the output of the FPGA with the result computed using a MATLAB program implemented in the same way as the VHDL (VHSIC Hardware Description Language) code. Based on the result of ex-vivo experiment using rabbit artery, the developed backend system was found to be suitable for real-time intravascular ultrasound imaging.

• YAKHAK HOEJI
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• v.56 no.4
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• pp.211-216
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• 2012

Drug dissolution test has been used for the purpose of both quality control of solid oral dosage forms and predicting in vivo drug release profiles. In this study, the dissolution profiles of buflomedil hydrochloride tablets and ticlopidine hydrochloride tablets were investigated according to the "Guidelines on Specifications of Dissolution tests for Oral dosage forms" of Korean Pharmacopoeia (KP). The analytical method using HPLC was validated. The validation was performed in terms of specificity, linearity, accuracy, precision and limit of quantitation.

• Journal of Sensor Science and Technology
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• v.29 no.2
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• pp.100-104
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• 2020

Thus far, several in vivo biosensing platforms have been proposed to measure the mechanical contractility of cultured cardiomyocytes. However, the low sensitivity and screening rate of the developed sensors severely limit their practical applications. In addition, intensive research and development in cardiovascular disease demand a high-throughput drug-screening platform based on biomimetic engineering. To overcome the drawbacks of the current state-of-the-art methods, we propose a high-throughput drug-screening platform based on 16 functional high-sensitivity well plates. The proposed system simulates the physiological accuracy of the heart function in an in vitro environment. We fabricated 64 cantilevers using highly flexible and optically transparent silicone rubber and placed in 16 independent wells. Nanogrooves were imprinted on the surface of the cantilever to promote cell alignment and maturation. The adverse effects of the cardiovascular drugs on the cultured cardiomyocytes were systematically investigated. The 64 cantilevers demonstrated a highly reliable and reproducible mechanical contractility of the drug-treated cardiomyocytes. Real-time high-throughput screening and simultaneous evaluation of the cardiomyocyte mechanical contractility under multiple drugs verified that the proposed system could be used as an efficient drugtoxicity test platform.

• YAKHAK HOEJI
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• v.57 no.3
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• pp.205-212
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• 2013

Dissolution test has been performed to control drug quality and to predict in vivo drug release profile of solid dosage forms, so there's a drift towards setting dissolution test instead of disintegration test. However, some solid dosage forms in Korea Pharmaceutical Codex (KPC) are not established the dissolution test yet, so these monographs are necessary to set the specification of dissolution test. In this study, we developed the specification and test method of dissolution test for itopride hydrochloride tablets and tiropramide hydrochloride tablets which are not established the dissolution test yet. According to the "Manual for Guideline Application for Validation of Analytical Procedures" and "Guidelines on Specification of Dissolution test for Oral dosage form" of Korean Pharmacopoeia (KP), we validated and established each development method. Based on the preliminary dissolution profile, we set the dissolution condition(paddle apparatus, pH 1.2 media, 50 rpm). For this condition, we performed the main dissolution test to determine the specification (45 min, 85%). Finally, we validated each analytical method by specificity, linearity, accuracy and precision. These developed methods will be included the next supplement of KPC and also contributed to the quality control of medicines.

• Mass Spectrometry Letters
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• v.10 no.2
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• pp.66-70
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• 2019

Rivaroxaban (RRN) is the first available active direct factor Xa inhibitor (anticoagulant) with oral administration. Due to its success in market, there have been efforts to develop various RRN formulations, and the development of good analytical methods for its in vivo evaluation is an essential prerequisite. Thus, here, a simple and efficient method to determine RRN in rat plasma using liquid-liquid extraction (LLE) and liquid chromatography and multiple reaction monitoring (LC-MRM) was presented. The use of ethyl acetate as the LLE solvent results appropriate extraction and purification of RRN and it also helps the significant reduction of rat plasma volume required for RRN quantitation. The developed method showed good analytical performance including specificity, linearity ($r^2{\geq}0.999$ within 0.5 - 500 ng/mL), sensitivity (the lower limit of quantitation at 0.5 ng/mL), accuracy (89.3 - 107.0%), precision (${\geq}12.7%$), and recovery (89.2 - 105.7%). Additionally, RRN in sample extracts showed good stability. Finally, the applicability of the validated method to the PK evaluation of RRN was confirmed after its oral administration to normal rats. The present method is the first analytical method employing LLE for the simple and efficient extraction and purification of RRN in rat plasma. Therefore, the present method can contribute to the development of new RRN formulations as well as to the monitoring of RRN in special clinical situations through its efficient determination in various samples with or without minor modification.

• Restorative Dentistry and Endodontics
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• v.35 no.6
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• pp.453-460
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• 2010

Objectives: To evaluate the accuracy and consistency of two different apex locators at both the Apex and 0.5 marks. Materials and Methods: Twenty-six root canals was scheduled for extraction for periodontal or prosthodontic reasons. Thirteen canals were measured using Root ZX and the rest by i-ROOT. The root canal length was measured both the at 0.5 mark and the Apex mark. The file was then fixed to the toot, and the distance from the file tip to the major foramen of each canal was measured after removing the root dentin under the microscope so that the major foramen and the file tip were seen. Results: 1. When the Apex mark was used, 100% of both the Root ZX and i-ROOT groups were within 0.5 mm of the major foramen. 2. When 0.5 mark was used, 100% of the Root ZX group and 77% of the i-ROOT group were within 0.5 mm of the major foramen. 3. In terms of standard deviation and quartile value, the Apex mark was more consistent than 0.5 mark in the Root ZX group, and 0.5 mark was more consistent in the i-ROOT group, but there was no statistically significant difference when compared with t-test. 4. The root canal length difference between the Apex mark and 0.5 mark was 0.22 mm and 0.46 mm in the Root ZX and i-ROOT groups, respectively. Conclusions: In this study, the Apex mark was the more consistent mark. Therefore, it is recommended to subtract 0.5 mm, which is the average length between the apex and apical constriction, from the root canal length at the Apex mark to obtain the working length clinically.