• The Journal of Korean Academy of Prosthodontics
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• v.58 no.2
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• pp.145-152
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• 2020

It is essential to record maxillomandibular relationship accurately for the harmony of esthetic and function in complete denture. Gothic arch tracing visually demonstrates the movement of the mandible, and is useful to establish accurate and reproducible centric relation. Proper retention and stability of complete denture in patients with severe alveolar bone resorption is difficult to attain. In such case, the closed mouth impression technique might be recommended. The denture border and impression are determined by patient's physiologic movement in the closed mouth impression technique. And, denture peripheral border is entirely closed with oral mucous membrane. This report presents satisfactory complete denture restoration using closed mouth impression technique and gothic arch tracing in patients with mandibular condyle fracture and severe absorption of mandibular alveolar ridge.

• Journal of the Korean Magnetics Society
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• v.8 no.6
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• pp.388-394
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• 1998

We designed and fabricated an improved null-type torque magnetometer for measuring magnetic anisotropy of magnetic materials. This torque magnetometer has a measurement range of $~{\pm}15$ dyne.cm, and the range can be controlled. Resolution is ~0.0005 dyne.cm. Noise level is less than 0.01 dyne.cm with one measurement, and less than 0.004 dyne.cm with 10 averaged measuremets. The precision is less than 0.5 %. In contrast to typical null-type torque magnetometers, we placed a small ferrite magnet in the Helmholtz coil, instead of placing coil in the permanent magnet. From this novel sturucture, we can design a geometrically isotropic and relatively light-weight sample rod. Also, we can prevent the effect of input and output lines of coil exposed in the magnetic field in torque meter. Consequently, our novel null-type torque magnetometer can have a better sensitivity, faster response time, and smaller distortion of torque curve than commercially available torque magnetometers.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.92-92
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• 2011

최근 건설기술의 발전과 함께 강재 케이블을 이용하는 시설물의 시공이 점점 증가하는 추세이다. 특히 현수교, 사장교와 같은 초장대 교량에 사용되는 케이블은 주거더 및 상판에 의한 하중의 대부분을 지지하는 핵심부재이다. 하지만 이러한 케이블 부재는 부식, 파단 등으로 인한 단면손실이 발생할 수 있고, 이로 인한 손상부의 응력집중으로 인해 시설물 전체의 붕괴로 이어질 수 있는 위험성을 가진다. 따라서 조기에 단면손실을 찾아 사고를 미연에 방지할 수 있는 강재 케이블 비파괴 검사 기술기반의 건전성 모니터링이 필수적이다. 이러한 효율적인 건전성 모니터링을 위해 스마트 센서를 활용한 연구가 활발히 이루어지고 있는데, 그중 대표적인 스마트 센서중 하나인 마그네틱 센서는 높은 신뢰도와 어디에나 적용 가능한 재현성 때문에 구조물 건전성 평가에 적용하기 유용한 기술로 그 적용범위가 선박, 항공등으로 점점 넓어지고 있는 추세이다. 마그네틱 센서는 그 적용대상에 따라 다양한 마그네틱 특성을 활용할 수 있는데, 최근에는 투자율 계측을 통해 케이블의 장력 측정이 가능한 Elasto-Magnetic 센서(E/M 센서)가 개발되었고 그 활용성에 대한 연구가 이뤄지고 있다. 이에 본 연구에서는 E/M 센서를 이용한 강재 케이블 모니터링 기술을 제안하고자 한다. E/M 센서는 본래 케이블의 장력측정을 위해 개발되었지만 본 연구에서는 강재 케이블 부재의 단면손실 검색을 위해 적용하였다. 제안된 기술의 실험적 검증을 위해 E/M 센서를 이용하여 4가지의 다른 직경을 가지는 강봉시편을 E/M 센서헤드의 1차 코일을 통해 자화시키고, 각각의 직경에서 출력전압을 2차 코일을 이용하여 계측하였다. 그 결과 강봉의 직경이 감소함에 따라 출력 전압이 감소함을 보였다. 반복실험을 통해 해상도 및 선형성이 확보되는 최적의 입력전압과 출력전압의 워킹포인트를 선정하였고, 선정된 조건에서 강봉시편을 일정 간격으로 스캔한 결과 단면감소에 따른 선형적인 출력전압 감소와 동시에 단면 변화 지점에서는 추세선에서 크게 벗어난 출력전압 계측값을 나타내었다. 본 실험을 통해 제안된 E/M 센서를 이용한 강재 케이블 모니터링 기술의 유용성 및 적용가능성을 확인할 수 있었다.

• The Korean Journal of Nuclear Medicine
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• v.37 no.6
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• pp.355-363
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• 2003

Purpose: Regional contractility can be calculated using the regional volume change of left ventricle measured by gated myocardial SPECT image and curve of central artery pressure obtained from radial artery pressure data. In this study, a program to obtain the regional contractility was developed, and reproducibility of regional contractility measurement was assessed. Materials and Methods: Seven patients(male:female=5:2, $58{\pm}11.9$ years) with coronary artery diseases underwent gated Tc-99m MIBI myocardial SPECT twice without delay between two scans. Regional volume change of left ventricle was estimated using CSA (Cardiac SPECT Analyzer) software developed in this study. Regional contractility was iteratively estimated from the time-elastance curve obtained using the time-pressure curve and regional time-volume curve. Reproducibility of regional contractility measurement assessed by comparing the contractility values measured twice from the same SPECT data and by comparing those measured from the pair of SPECT data obtained from a same patient. Results: Measured regional contractility was $3.36{\pm}3.38{mm}Hg/mL$ using 15-segment model, $3.16{\pm}2.25{mm}Hg/mL$ using 7-segment model, and $3.11{\pm}2.57{mm}Hg/mL$ using 5-segment model. The harmonic average of regional contractility value was almost identical to the global contractility. Correlation coefficient of regional contractility values measured twice from the same data was greater than 0.97 for all models, and two standard deviations of contractility difference on Bland Altman plot were 1.5%, 1.0%, and 0.9% for 15-, 7-, and 5-segment models, respectively. Correlation coefficient of regional contractility values measured from the pair of SPECT data obtained from a same patient was greater than 0.95 for all models, and two standard deviations on Bland Altman plot were 2.2%, 1.0%, and 1.2%. Conclusion: Regional contractility of left ventricle measured using developed software in this study was reproducible. Regional contractility of left ventricle will be a new useful index for myocardial function after analysis of the clinical data.

• Journal of the Korean GEO-environmental Society
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• v.13 no.11
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• pp.93-101
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• 2012

SCP is a construction method that maximizes the effects of ground improvement by creating sand piles, which are formed by the compaction within soft ground. SCP is mainly used for consolidation and drain effects in clayey soils, and as a liquefaction countermeasure through effects such as compaction in loose sandy soils. In the design of SCP, if the sand piles with high stiffness are not taken into account, it can become a design that overly considered safety, and increased construction costs are highly likely to cause economic disadvantages. The changes in stress conditions and compaction mechanisms in the subsurface have been identified to a certain extent by study findings to date. However, the studies that considered SCP and in-situ ground as composite ground are fairly limited, and therefore, those studies have not achieved enough results to fully explain the relevant topics. In this study, the ground improved by SCP was regarded as the composite ground that consists of SCP and in-situ ground. Moreover, employing a CID test, this study examined the changes in the stress conditions of in-situ ground according to the installation of SCP through the relations between $K_0$ and SCP replacement ratio. At the same, whether the SCP installation procedure can be recreated in a laboratory was examined using a cyclic triaxial test. According to the test results, the changes in the stress conditions of the original ground occurred most largely in an initial stage of SCP installation, and after a certain time point, the vibration for SCP installation did not have a great influence on the changes in the stress conditions of the ground. Moreover, in order to recreate the behaviors of in-suit ground according to SCP in a laboratory, cyclic loading, which corresponds to casing vibration, was concluded to be essentially required.

• Journal of Food Hygiene and Safety
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• v.34 no.6
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• pp.519-525
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• 2019

The Ministry of Food and Drug Safety (MFDS) is amending its test methods for health functional foods (dietary food supplements) to establish regulatory standards and specifications in Korea. In this regard, we are continuing our research on analytical method development for the items listed in the Korean Health Functional Food Codex. In this study, we have developed a sensitive and selective test method that could simultaneously separate and determine coenzyme Q10 based on liquid chromatographic-tandem mass spectrometry (LC-MS/MS). Calibration curves showed linearity with a correlation coefficient (R²) of > 0.999 and the limits of detection (LODs) and limits of quantitation (LOQs) were in the range of 26.0 ㎍/L and 78.9 ㎍/L, respectively. The recovery results ranged between 98.6-107.0% at 3 different concentration levels with relative standard deviations (RSDs) less than 5%. The proposed analytical method was characterized with high resolution of the coenzyme Q10 and the assay was fully validated as well.

• The Korean Journal of Pesticide Science
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• v.16 no.4
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• pp.391-394
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• 2012

Exposure and risk assessment during mixing/loading of chlorpyrifos emulsifiable concentrate (EC, 20%) were carried out. Limit of detection and limit of quantitation were 0.02 and 0.1 ng, respectively. Calibration curve linearity and reproducibility were excellent. Recovery of chlorpyrifos from gloves was 72.3-103.4%. During mixing/loading procedure, average hand exposure amount of chlorpyrifos was 3.9 mg which is corresponding to 0.004% of total active ingredient in the prepared spray mixture. In calculation of MOS (Margin of Safety) for risk assessment, male Korean average body weight and AOEL (Acceptable Operator Exposure Level) were used. Nine events of mixing/loading procedure were assumed per day. And 75 percentile of 30 repetition (4.6 mg) was used as for the worst case. MOS was more than 1 for total repetition, indicating mixing/loading work was of least risk. However, MOS of individual repetition was examined, two cases were less than 1 suggesting careful work habit is essential in mixing/loading procedure.

• Journal of Food Hygiene and Safety
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• v.32 no.3
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• pp.193-198
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• 2017

Scutellaria baicalensis, Eleutherococcus senticosus, and Angelica sinensis have been used as raw materials for health functional foods. This study was conducted to develop a novel method to analyze levels of baicalin (Scutellaria baicalensis), eleutheroside E (Eleutherococcus senticosus), and ligustilide (Angelica sinensis) simultaneously in health functional foods. The methanol extracted samples were analyzed and quantified via liquid chromatography-tandem mass spectrometry (LC-MS/MS) in the positive ion mode and the negative ion mode using multiple reaction monitoring. Standard calibration curves confirmed linearity with the correlation coefficient ($r^2$) of > 0.99 at $100-2000{\mu}g/mL$ concentration range. The limits of detection (LODs) and limits of quantitation (LOQs) were in the range of $13.0{\sim}35.2{\mu}g/L$ and $39.3{\sim}106.7{\mu}g/L$, respectively. The recovery results ranged between 91.4~109.9% at 3 different concentration levels with relative standard deviations (RSDs) less than 5%. The proposed analytical method was characterized with high accuracy and acceptable precision. The new method would be an effective tool to analyze baicalin, eleutheroside E, and ligustilide simultaneously in raw materials of health functional foods.

• Analytical Science and Technology
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• v.19 no.1
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• pp.96-102
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• 2006

Trimethylamine (TMA) is one of the difficult odorous compounds for the collection and analysis. Although sulfuric acid absorption and/or sulfuric acid impregnated filter method are commonly recommended for its sampling, these methods also suffer from difficulties involved in sample treatment and operational procedures. Hence, as an ancillary approach to measure TMA, we investigated the combination of bag sampling and SPME analysis for TMA measurements. For the purpose of our study, we investigated the following three subjects: 1) temporal variability of standard storage, 2) bag loss effect of TMS, and 3) TMA loss due to repetitive analysis of an identical bag sample. According to our storage test up to 7 or 20 dyas, TMA loss were found to occur up to 40 to 50% within relatively short period of up to 48 hrs depending on its concentration ranges. When the tests were made for bag loss by transferring TMA standards across different size bags, we were able to find that the extent of bag loss are not significant with 5 to 20% loss rate. Finally, the TMA sorptive loss via its exposure to SPME fiber was generally estimated to run from 2 to 3%.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.14 no.4
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• pp.537-549
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• 2001

The effect of partially restrained(PR) connections and the uncertainties in them on the reliability of steel frames subjected to seismic loading is addressed. A stochastic finite element method(SFEM) is proposed combining the concepts of the response surface method(RSM), the finite element method(FEM), the first-order reliability method (FORM), and the iterative linear interpolation scheme. The behavior of PR connections is captured using moment-relative rotation curves, and is represented by the four-parameter Richard model. For seismic excitation, the loading, unloading, and reloading behavior at PR connections is modeled using moment-relative rotation curves and the Masing rule. The seismic loading is applied in the time domain for realistic representation. The reliability of steel frames in the presence of PR connections is calculated considering all major sources of nonlinearity. The algorithm is clarified with the help of an example.