• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 2002년도 Proceedings
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• pp.231-232
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• 2002

We have been developing microvolume LET counter in order to measure the three-dimensional LET distribution of the therapeutic heavy ion radiation volumes in the water phantom. With help of the technique of cathode induced carhge readout, this detector has a rectangular (box-shape) sensitive volume of which size is about 1 mm$^2$ and 2mm (depth).

• 한국의학물리학회지:의학물리
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• 제33권4호
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• pp.80-87
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• 2022

Purpose: Proton therapy has different relative biological effectiveness (RBE) compared with X-ray treatment, which is the standard in radiation therapy, and the fixed RBE value of 1.1 is widely used. However, RBE depends on a charged particle's linear energy transfer (LET); therefore, measuring LET is important. We have developed a LET measurement method using the inefficiency characteristic of an EBT3 film on a proton beam's Bragg peak (BP) region. Methods: A Gafchromic EBT3 film was used to measure the proton beam LET. It measured the dose at a 10-cm pristine BP proton beam in water to determine the quenching factor of the EBT3 film as a reference beam condition. Monte Carlo (MC) calculations of dose-averaged LET (LET_d) were used to determine the quenching factor and validation. The dose-averaged LETs at the 12-, 16-, and 20-cm pristine BP proton beam in water were calculated with the quenching factor. Results: Using the passive scattering proton beam nozzle of the National Cancer Center in Korea, the LET_d was measured for each beam range. The quenching factor was determined to be 26.15 with 0.3% uncertainty under the reference beam condition. The dose-averaged LETs were measured for each test beam condition. Conclusions: We developed a method for measuring the proton beam LET using an EBT3 film. This study showed that the magnitude of the quenching effect can be estimated using only one beam range, and the quenching factor determined under the reference condition can be applied to any therapeutic proton beam range.

• Journal of the Korean Statistical Society
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• 제19권2호
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• pp.105-112
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• 1990

Let (X, Y) be a pair random variables and let f denote the regression function of the response Y on the measurement variable X. Let K(f) denote a derivative of f. The least squares method is used to obtain a tensor spline estimator $\hat{f}$ of f based on a random sample of size n from the distribution of (X, Y). Under some mild conditions, it is shown that $K(\hat{f})$ achieves the optimal rate of convergence for the estimation of K(f) in $L_2$ and $L_{\infty}$ norms.

• Journal of the Korean Statistical Society
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• 제21권2호
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• pp.153-166
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• 1992

Consider an unknown regression function f of the response Y on a d-dimensional measurement variable X. It is assumed that f belongs to a tensor Sobolev space. Let T denote a differential operator. Let $\hat{T}_n$ denote an estimator of T(f) based on a random sample of size n from the distribution of (X, Y), and let $\Vert \hat{T}_n - T(f) \Vert_2$ be the usual $L_2$ norm of the restriction of $\hat{T}_n - T(f)$ to a subset of $R^d$. Under appropriate regularity conditions, the optimal rate of convergence for $\Vert \hat{T}_n - T(f) \Vert_2$ is discussed.

• 센서학회지
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• 제23권3호
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• pp.197-201
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• 2014

TEPC (Tissue Equivalent Proportional Counter) was usually used for high LET radiation dosimetry. We developed a prototype TEPC for micro-dosimetry in the range of $0.2{\sim}300 keV/{\mu}m$. And, the simulated site diameter of the TEPC is $2{\mu}m$, of similar size to a cell nucleus. For purposes of characterization the response for high LET radiation of the TEPC has been investigated under 135MeV/u Carbon ions in HIMAC (Heavy Ion Medical Accelerator). We determined the gas multiplication factor and measured the lineal energy spectrum [yd(y)] of 135 MeV/u Carbon ions. The value of the gas multiplication factor was 315 at 700 V bias voltage. As a result of the experiment, we could more understand the performance of the TEPC for high LET (Linear Energy Transfer) radiation. And the procedure of high LET radiation dosimetry using TEPC is established.

• 한국의학물리학회:학술대회논문집
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• 한국의학물리학회 1999년도 Japanese Journal of Medical Physics
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• pp.387-389
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• 1999

• 한국전자거래학회지
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• 제18권1호
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• pp.1-12
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• 2013

온라인 환경에서 개인정보의 사용 빈도가 많아짐과 동시에 제 3자에 의한 개인정보 수집 및 저장의 가능성도 높아지고 있다. 인터넷 서비스 제공에 사용되는 개인정보는 본인이 원하지 않는 용도로 사용되나 타인에게 유출되는 경우 뜻하지 않는 추가피해를 불러올 수 있다. 비록 개인정보 관리 제도의 개선이 이루어지고 있으나 여전히 개인정보의 유출 사례를 주변에서 손쉽게 찾아볼 수 있다. 개인정보보호에 관한 보다 합당한 투자 근거를 제시하기 위해서는 개인정보 유출로 인해 발생될 수 있는 피해의 측정이 선행되어야 한다. 본 논문은 해당 측정 방법의 하나인 개인정보 유출을 겪은 기업의 주가 변화를 측정하여 개인정보보호법 시행 이전보다 개인정보 보안과 관련한 인식이 개선되었는지 검증한다. 실증분석의 결과는 제도적 개선이 이루어지고 있음에도 불구하고 자본시장에서의 개인정보 유출로 인한 피해 인식은 크게 변화되지 않고 있음을 확인해 주고 있다. 여전히 주기적으로 발생하는 정보 보안 사건의 적극적 예방을 위해서는 그 피해액의 산정에 있어 개인의 추가 피해 가능성을 광범위하게 인정하는 전향적인 태도와 함께 피해 배상에 대한 의무를 명확히 인식할 수 있도록 추가적인 개선이 선행되어야 할 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.479-484
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• 1996

This paper describes a method of measuring tilt motion. This method measures the tilt motion of drilling machines using a laser interferometer, a simple sliding linear bearing, measurement of the probe and the LSC(least square center) method. The next order of business is discussing the procedure of measurement. First, The measured position is considered to be the point of contact between the drill shank and the probe. The revolution of the drill axis delivers the point of contact to the probe. Second, because the laser interferometer is attached on the sliding linear bearing, any movement of probe influences laser reflector. Thus, the laser program displays the moving factor of laser reflector. Namely, this is tilt factor. Third. the points of measurement are a full circle which has 8 points (each are 45$^{\circ}$), After it is finished measuring the 8 points, let the spindle of the drilling machine move down about 5 cm. Repeating this procedure three times, we can get tilt motion's values which are calculated by LSC method. Many error factors affect the accurate measurement of tilt motion. However in this paper we ignore some error factors because they are less significant than tilt motion.

• 대한인간공학회:학술대회논문집
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• 대한인간공학회 1996년도 춘계학술대회논문집
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• pp.291-300
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• 1996

This study is to determine the biomechanical characteristics of Korean. Male 58 and Female 54 were participated for the measurement which was performed by immersion method and reaction board method. Body parts were head with neck, trunk, upper arm, forearm, hand, thigh, leg, and foot. Their volumes were measures by immersion method. Their weight were determined by using Dempster(1995), Drills and Contini(1969) density data. Each center of body part weight were determined by specific posture on the reaction board. The postures were asked to the subject forearm- lifted posture, total let- lifted posture, foot-lifted posture. According to each posture, the center of each part were calculated.

• Journal of Advanced Marine Engineering and Technology
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• 제26권4호
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• pp.439-449
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• 2002

Experimental investigations of the flow structure and heat transfer enhancement in a channel with a built-in circular cylinder and a wing-let type vortex generator are presented. Without any vortex generators, relatively low heat transfer takes place in the downstream of the circular cylinder where is a recirculation region with low velocity fluid is formed. However with a wing-let type longitudinal vortex generator in the wake region behind the cylinder, heat transfer in the region can be enhanced. In order to control the strength of longitudinal vortices, the angle of attack of the vortex generators is varied from $20^{circ} to 45^{\circ}$, but spacings between the vortex generations are fixed to be 5 mm. The 3-dimensional mean velocity field downstream of the vortex generator is measured by a five-hole pressure probe, and the hue-capturing method using thermochromatic liquid crystals has been used to provide the local distribution of the heat transfer coefficient. The vorticity field and streamwise velocity contour are obtained from the velocity field. Streamwise distributions of averaged Stanton number on the measurement planes show very similar trends for all the experimental cases($\beta=20^{circ}, 30^{circ} and 45^{\circ}$). Circulation strength and heat transfer coefficient have the maximum values when the angle of attack($\beta$) is $30^{\circ}$.