• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.103-103
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• 2002

목적：자화율 대조법을 사용한 관류 영상에서 동시획득 $T_{1}T_{2}^{*}$ 강조 경사 자장 펄스열을 사용하여 Gd-DTPA에 의한 $T_{1}T_{2}^{*}$ 감소 효과를 동시에 획득하여 종양의 치료 효과, 판정에 중요한 기준을 제시할 수 있는 정확한 관류 정보를 얻고자 한다. 대상 및 방법： Gd-DTPA에 의한 $T_{1}T_{2}^{*}$ 감소 효과를 동시에 획득하기 위하여 기존의 이중 경사자장 펄스열을 수정, 동시획득 $T_{1}T_{2}^{*}$ 강조 경사자장 펄스열을 개발하였고, 시간 해상도를 높이기 위하여 key-hole 방법을 사용하였다. 고정 phantom으로 Sephadex를 다양한 농도의 Gd-DTPA 용액에 swelling하여 사용하였고, 관류 phantom으로는 Sephadex와 Dialyzer를 사용하였다. Sephadex는 swelling 하였을 때 $T_1$, $T_2$값이 생체 조직의 값과 비슷하고, 물을 관류시킬 수 있어 생체 모형에 적합한 phantom이다 .관류 phantom은 정량 펌프에 연결하여 사용하였다. Sephadex 관류 phantom에서는 분당 약 4$m\ell$ 속도로 관류시키면서 25 mM Gd-DTPA을 0.1$m\ell$ 일시 주입하여 관류 방향에 수직인 coronal 영상을 약 15분 동안 얻었다. 투과도를 구하기 위한 phantom으로는 hollow fiber type Dialyzer를 사용하였고, in vivo에서 1차 관류 이후에 현관 밖에서의 Gd농도가 높고 혈관 내부의 농도가 낮은 상태를 만들기 위하여 fiber 바깥쪽으로 500 mM Gd-DTPA 2 ml를 미리 넣어두고 fiber 내부로 이보다 낮은 농도의 Gd 용액을 관류시키면서 약 1시간동안 영상을 얻었다. 관류 영상에서 $T_1$/$T_{2}^{*}$ 감소 효과를 구분하여 구한 $\DeltaR_1$, $\DeltaR_2$ 곡선의 적분값으로부터 관류량을 구하고, 2 구획 모델을 적용하여 투과도를 구했다.

• Proceedings of the KSMRM Conference
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• 2002.11a
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• pp.127-127
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• 2002

목적： 자화율 대조법을 사용한 관류 영상에서 동시획득 $T_{1}{/}T_{2}^{*}$ 강조 경사 자장 펄스열을 사용하여 Gd-DTPA에 의한 $T_{1}{/}T_{2}^{*}$ 감소 효과를 동시에 획득하여 종양의 치료 효과, 판정에 중요한 기준을 제시할 수 있는 정확한 관류 정보를 얻고자 한다. 대상 및 방법： Gd-DTPA에 의한 $T_{1}{/}T_{2}^{*}$ 감소 효과를 동시에 획득하기 위하여 기존의 이중 경사자장 펄스열을 수정, 동시획득 $T_{1}{/}T_{2}^{*}$ 강조 경사자장 펄스열을 개발하였고, 시간 해상도를 높이기 위하여 key-hole 방법을 사용하였다. 고정 phantom으로 Sephadex를 다양한 농도의 Gd-DTPA 용액에 swelling하여 사용하였고, 관류 phantom으로는 Sephadex와 Dialyzer를 사용하였다. Sephadex는 swelling 하였을 때 $T_1$, $T_2$값이 생체 조직의 값과 비슷하고, 물을 관류시킬 수 있어 생체 모형에 적합한 phantom이다. 관류 phantom은 정량 펌프에 연결하여 사용하였다. Sephadex 관류 phantom에서는 분당 약 4$m\ell$ 속도로 관류시키면서 25 mM Gd-DTPA을 0.1$m\ell$ 일시 주입하여 관류 방향에 수직인 coronal 영상을 약 15분 동안 얻었다. 투과도를 구하기 위한 phantom으로는 hollow fiber type Dialyzer를 사용하였고, in vivo에서 1차 관류 이후에 혈관 밖에서의 Gd 농도가 높고 혈관 내부의 농도가 낮은 상태를 만들기 위하여 fiber 바깥쪽으로 500mM Gd-DTPA 2$m\ell$를 미리 넣어두고 fiber 내부로 이보다 낮은 농도의 Gd 용액을 관류시키면서 약 1시간동안 영상을 얻었다. 관류 영상에서 $T_{1}{/}T_{2}^{*}$ 감소 효과를 구분하여 구한 $\Delta{R}_{1}$, $\Delta{R}_{2}^{*}$ 곡선의 적분값으로부터 관류량을 구하고, 2 구획 모델을 적용하여 투과도를 구했다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.227-227
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• 2021

하천수의 효율적인 관리와 균형적인 물배분을 위해 신뢰도 있는 하천수 사용량 계측자료가 필수적이다. 공업·생활용수는 유량계를 설치하여 취수량에 대한 신뢰도 있는 자료를 홍수통제소에 보고하고 있으나, 농업용수는 유량계 설치 지점이 적고, 수문조작 등의 간접적인 계측방법 허용으로 취수량 자료의 신뢰도가 낮은 실정이다. 본 연구에서는 만경강 상류의 취수보를 대상으로 시험 유역 운영 및 검증을 통해 직접 계측방법의 취수량 산정 정확도를 비교하였다. 적용한 직접 계측방법은 초음파법, 전자파법, 수위-유량관계법으로 산정된 취수량 자료간의 절대오차 비교를 통해 정확도를 평가하였다. 점단위 취수량 자료 비교시, 현장측정값 대비 초음파법 5.86%, 전자파법 7.28%, 수위-유량관계법 11.84%의 오차가 발생하는 것으로 산정되어 초음파법이 가장 높은 정확도를 가지는 것으로 나타났고, 일단위, 월단위 자료 비교시 기준값으로 설정하였다. 일단위 취수량 자료 비교시, 초음파법으로 산정한 일평균 취수량 대비 전자파법 6.62%, 수위-유량관계법 8.62%의 오차가 발생하였다. 월단위 취수량 자료 비교시, 초음파법으로 산정한 월평균 취수량 대비 전자파법 5.81%, 수위-유량관계법 11.03%의 오차가 발생하였다. 산정된 취수량의 정확도는 초음파법, 전자파법, 수위-유량관계법 순이다. 고가의 첨단 계측장비를 적용하여 연속적인 유속 계측을 통해 산정한 취수량이 신뢰도가 높은 것으로 나타났다. 농업용수는 사용시설별 취수량 규모 편차가 크기 때문에, 추후 중요도가 높은 사용시설과 비교적 낮은 시설간의 구분을 통한 직접 계측방법의 최적 선정 후속연구가 필요하다.

• Radiation Oncology Journal
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• v.24 no.3
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• pp.185-191
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• 2006

[ $\underline{Purpose}$ ]: Standardization quality assurance (QA) program of CyberKnife for suitable circumstances in Korea has not been established. In this research, we investigated the development of QA program for CyberKnife and evaluation of the feasibility under applications. $\underline{Materials\;and\;Methods}$: Considering the feature of constitution for systems and the therapeutic methodology of CyberKnife, the list of quality control (QC) was established and divided dependent on the each period of operations. And then all these developed QC lists were categorized into three groups such as basic QC, delivery specific QC, and patient specific QC based on the each purpose of QA. In order to verify the validity of the established QA program, this QC lists was applied to two CyberKnife centers. The acceptable tolerance was based on the undertaking inspection list from the CyberKnife manufacturer and the QC results during last three years of two CyberKnife centers in Korea. The acquired measurement results were evaluated for the analysis of the current QA status and the verification of the propriety for the developed QA program. $\underline{Results}$: The current QA status of two CyberKnife centers was evaluated from the accuracy of all measurements in relation with application of the established QA program. Each measurement result was verified having a good agreement within the acceptable tolerance limit of the developed QA program. $\underline{Conclusion}$: It is considered that the developed QA program in this research could be established the standardization of QC methods for CyberKnife and confirmed the accuracy and stability for the image-guided stereotactic radiotherapy.

• Progress in Medical Physics
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• v.16 no.4
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• pp.166-175
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• 2005

The purpose of this study is to develop the optimization method for adjusting the film isocenter shift and to suggest the quantitative acceptable criteria for film dosimetry after optimization In the dynamic conformal arc radiation therapy (DCAR). The DCAR planning was peformed In 7 patients with brain metastasis. Both absolute dosimetry with ion chamber and relative film dosimetry were peformed throughout the DCAR using BrainLab's micro-multileaf collimator. An optimization method for obtaining the global minimum was used to adjust for the error in the film isocenter shift, which is the largest pan of systemic errors. The mean of point dose difference between measured value using ion chamber and calculated value acquired from planning system was $0.51{\pm}0.43\%$ and maximum was $1.14\%$ with absolute dosimetry These results were within the AAPM criteria of below $5\%$. The translation values of film isocenter shift with optimization were within ${\pm}$1 mm in all patients. The mean of average dose difference before and after optimization was $1.70{\pm}0.35\%$ and $1.34{\pm}0.20\%$, respectively, and the mean ratios over $5\%$ dose difference was $4.54{\pm}3.94\%$ and $0.11{\pm}0.12\%$, respectively. After optimization, the dose differences decreased dramatically and a ratio over $5\%$ dose difference and average dose difference was less than $2\%$. This optimization method is effective in adjusting the error of the film isocenter shift, which Is the largest part of systemic errors, and the results of this research suggested the quantitative acceptable criteria could be accurate and useful in clinical application of dosimetric verification using film dosimetry as follows; film isocenter shift with optimization should be within ${\pm}$1 mm, and a ratio over $5\%$ dose difference and average dose difference were less than $2\%$.

• Journal of Biomedical Engineering Research
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• v.19 no.6
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• pp.595-602
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• 1998

Among the apex locators, the frequency dependent type is more accurate and convenient to use than others, But the accuracy of the apex locator is still influenced by the presence of various electrolytes used in root canal treatments. In this study, we have developed a frequency dependent electronic apex locator minimizing the influence of the electrolytes on the measurement of root canal lengths. It was also confirmed that two frequencies of 500Hz and 100kHz are optimal for the measuring impedance compare with commercial product used(400Hz and 8kHz)a and there were no differences in accuracy among the three different types of the waveforms; sinusoidal, triangular, and rectangular waves(p>0.05). Impedance ratio of the two different frequencies represents the position of the file in root canal, and the voltage difference of two signals represents the status of the fluid in the root canal. As a result of compensation using the voltage differences, the errors were decreased on the average from +0.54mm to +0.18mm in $H_2O_2$ solution (p<0.01), and from -0.33mm to -0.01mm in NaOCl solution(p<0.01). The accuracies based on ${\pm}$0.5mm, in $H_2O_2$ and NaOCl solutions were improved with the automatic compensation from 71.1% and 91.1% to 82.2% and 100% respectively.

• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.5
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• pp.552-560
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• 2013

In this paper, an optimization algorithm for the block assembly accuracy control assessment is proposed with consideration for the current block assembly process and accuracy control procedure used in the shipbuilding site. The objective function of the proposed algorithm consists of root mean square error of the distances between design and measured data of the other control points with respect to a specific point of the whole control points. The control points are divided into two groups: points on the control line and the other points. The grouped data are used as criteria for determining the combination of 6 degrees of freedom in the registration process when constituting constraints and calculating objective function. The optimization algorithm is developed by using combination of the sampling method and the point to point relation based modified ICP algorithm which has an allowable error check procedure that makes sure that error between design and measured point is under allowable error. According to the results from the application of the proposed algorithm with the design and measured data of two blocks data which are verified and validated by an expert in the shipbuilding site, it implies that the choice of whole control points as target points for the accuracy calculation shows better results than that of the control points on the control line as target points for the accuracy of the calculation and the best optimized result can be acquired from the accuracy calculation with a fixed point on the control line as the reference point of the registration.

• Journal of the Korean GEO-environmental Society
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• v.19 no.11
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• pp.5-14
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• 2018

Worldwide, soil compaction work is one of the most important activities that are carried out on civil engineering works sites. Compaction work, particularly in the area of road construction, is considered to be important, as poor compaction work is closely related with poor construction even after a construction is complete. Currently, the plate bearing test or the sand cone method relative to the unit weight of soil test are commonly used to measure the degree of compaction, but as these require a great deal of time, equipment and manpower, it is difficult to secure economic efficiency. The method that is used to measure the degree of compaction according to the penetration depth achieved by free fall objects through gravity is the Free-Fall Penetration Test (FFPT), which uses a so-called "portable compaction measuring meter (PCMM)." In this study, the degree of compaction was measured and a penetration depth graph was developed after the field test using the portable compaction measuring meter. The coefficient of determination was 0.963 at a drop height of 10 cm, showing the highest level of accuracy. Both horizontal axis and longitudinal axis were developed in a decimal form of graph, and the range of allowable error was ${\pm}1.28mm$ based on the penetration depth. The portable compaction measuring meter makes it possible to measure the degree of compaction simply, quickly and accurately in the field, which will ensure economic efficiency and facilitate the process management.

• Journal of radiological science and technology
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• v.32 no.4
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• pp.361-370
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• 2009

The image quality management of bone mineral density is the responsibility and duty of radiologists who carry out examinations. However, inaccurate conclusions due to lack of understanding and ignorance regarding the methodology of image quality management can be a fatal error to the patient. Therefore, objective of this paper is to understand proper image quality management and enumerate methods for examiners and patients, thereby ensuring the reliability of bone mineral density exams. The accuracy and precision of bone mineral density measurements must be at the highest level so that actual biological changes can be detected with even slight changes in bone mineral density. Accuracy and precision should be continuously preserved for image quality of machines. Those factors will contribute to ensure the reliability in bone mineral density exams. Proper equipment management or control methods are set with correcting equipment each morning and after image quality management, a phantom, recommended from the manufacturer, is used for ten to twenty-five measurements in search of a mean value with a permissible range of ${\pm}1.5%$ set as standard. There needs to be daily measurement inspections on the phantom or at least inspections three times a week in order to confirm the existence or nonexistence of changes in values in actual bone mineral density. in addition, bone mineral density measurements were evaluated and recorded following the rules of Shewhart control chart. This type of management has to be conducted for the installation and movement of equipment. For the management methods of inspectors, evaluation of the measurement precision was conducted by testing the reproducibility of the exact same figures without any real biological changes occurring during reinspection. Bone mineral density inspection was applied as the measurement method for patients either taking two measurements thirty times or three measurements fifteen times. An important point when taking measurements was after a measurement whether it was the second or third examination, it was required to descend from the table and then reascend. With a 95% confidence level, the precision error produced from the measurement bone mineral figures came to 2.77 times the minimum of the biological bone mineral density change. The value produced can be stated as the least significant change (LSC) and in the case the value is greater, it can be stated as a section of genuine biological change. From the initial inspection to equipment moving and shifter, management must be carried out and continued in order to achieve the effects. The enforcement of proper quality control of radiologists performing bone mineral density inspections which brings about the durability extensions of equipment and accurate results of calculations will help the assurance of reliable inspections.

• Korean Journal of Environmental Agriculture
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• v.32 no.1
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• pp.70-77
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• 2013

BACKGROUND: Nitroxoline is an antibiotic agent. It is used for the treatment of the second bacterial infection by the colibacillosis, salmonellosis and viral disease of the poultry. When the nitroxoline is indiscreetly used, the problem about the abuse of the antibiotics can occur. Therefore, this study presented the residue analytical method of nitroxoline in food for the safety management of animal farming products. METHODS AND RESULTS: A simple, sensitive and specific method for nitroxoline in chicken muscle by high performance liquid chromatograph with PDA was developed. Sample extraction with acetonitrile, purification with SPE cartridge (MCX) were applied, then quantitation by HPLC with C18 column under the gradient condition with 0.1 % tetrabutylammonium hydroxide-phosphoric acid and methanol was performed. Standard calibration curve presented linearity with the correlation coefficient ($r^2$) > 0.999, analysed from 0.02 to 0.5 mg/L concentration. Limit of quantitation in chicken muscle showed 0.02 mg/kg, and average recoveries ranged from 72.9 to 88.1 % in chicken muscle. The repeatability of measurements expressed as coefficient of variation (CV %) was less than 12 % in 0.02 and 0.04 mg/kg. CONCLUSION(S): Newly developed method for nitroxoline in chicken muscle was applicable to food inspection with the acceptable level of sensitivity, repeatability and reproducibility.