• Journal of Korea Water Resources Association
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• v.48 no.5
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• pp.367-377
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• 2015

ADCPs have been highlighted so far for measuring steramflow discharge in terms of their high-order of accuracy, relatively low cost and less field operators driven by their easy in-situ operation. While ADCPs become increasingly dominant in hydrometric area, their actual measurement accuracy for velocity and bathymetry measurement has not been sufficiently validated due to the lack of reliable bench-mark data, and subsequently there are still many uncertain aspects for using ADCPs in the field. This research aimed at analyzing inter-comparison results between ADCP measurements with respect to the detailed ADV measurement in a specified field environment. Overall, 184 ADV points were collected for densely designed grids for the given cross-section that has 6 m of width, 1 m of depth, and 0.7 m/s of averaged mean flow velocity. Concurrently, ADCP fixed-points measurements were conducted for each 0.2m and 0.02m of horizontal and vertical spacing respectively. The inter-comparison results indicated that ADCP matched ADV velocity very accurately for 0.4~0.8 of relative depth (y/h), but noticeable deviation occurred between them in near surface and bottom region. For evaluating the capacity of measuring bathymetry of ADCPs, bottom tracking bathymetry based on oblique beams showed better performance than vertical beam approach, and similar results were shown for fixed and moving-boat method as well. Error analysis for velocity and bathymetry measurements of ADCP can be potentially able to be utilized for the more detailed uncertainty analysis of the ADCP discharge measurement.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.917-925
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• 2005

In this paper, the quad-band antenna for mobile handsets is proposed and developed. The operating frequency bands include GSM(880 MHz${\~}$960 MHz), GPS(1,575 MHz$\pm$10 MHz), DCS(1,710 MHz${\~}$l,880MHz), and PCS(1,850 MHz${\~}$l,990 MHz). The proposed antenna consists of a feed line, a shorting post, and a radiating element of the feed loop. The multi-band operation is achieved by using the fundamental and higher resonant modes of the radiating element. Based on analysis of the current distribution on the radiator, the resonant frequency of each mode can be adjusted by adding the different sizes of slots on the radiator. The radiator of the feed loop is designed to be symmetrical so that the energy is symmetrically distributed on the radiator, which results in omni-directional radiation pattern. The ground plane under the radiator is removed in order to improve the bandwidth. The measured impedance bandwidths are $10.1\%$ in GSM band(VSWR<2.5), $26.8\%$ in GPS band, and DCS/US-PCS bands(VSWR<2.5), respectively. The maximum gains on the H-plane of the fabricated antenna are measured about -0.37 dBi${\~}$2.55 dBi for all operating frequency bands.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.879-884
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• 2005

The setting time is a very important factor affecting the quality of tunnel lining and reinforcement of inclined slope etc. Currently, however, the quality criteria of accelerating admixture to improve it is not established well. In this study, evaluation on setting time measuring methods of cement mixed a accelerating admixture (AA) was performed using Gillmore and Vicat needle test methods. For both test methods, the setting time for addition at a time was better than post addition regardless of initial setting and final setting. For Gillmore needle test method, two types of measuring methods were selected and it is noted that setting time with cement type under the same accelerating admixture can be different. Accordingly, manufacturing company shall develop a less sensitive accelerating admixture to cement type. For Vicat needle test method, six types of measuring methods were used and a proper measuring method of the admixture were proposed as follows: (1) the temperature of materials used shall be controlled exactly and (2) to evaluate its properties, an admixture usage of $5\%$ (ratio of cement weight) is recommended.

• Radiation Oncology Journal
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• v.20 no.4
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• pp.396-404
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• 2002

Purpose : Many papers support a correlation between rectal complications and rectal doses in uterine cervical cancer patients treated with radical radiotherapy. In vivo dosimetry in the rectum following the ICRU report 38 contributes to the quality assurance in HDR brachytherapy, especially in minimizing side effects. This study compares the rectal doses calculated in the radiation treatment planning system to that measured with a silicon diode the in vivo dosimetry system. Methods : Nine patients, with a uterine cervical carcinoma, treated with Iridium-192 high dose rate brachytherapy between June 2001 and Feb. 2002, were retrospectively analysed. Six to eight-fractions of high dose rate (HDR)-intracavitary radiotherapy (ICR) were delivered two times per week, with a total dose of $28\~32\;Gy$ to point A. In 44 applications, to the 9 patients, the measured rectal doses were analyzed and compared with the calculated rectal doses using the radiation treatment planning system. Using graphic approximation methods, in conjunction with localization radiographs, the expected dose values at the detector points of an intrarectal semiconductor dosimeter, were calculated. Results : There were significant differences between the calculated rectal doses, based on the simulation radiographs, and the calculated rectal doses, based on the radiographs in each fraction of the HDR ICR. Also, there were significant differences between the calculated and measured rectal doses based on the in-vivo diode dosimetry system. The rectal reference point on the anteroposterior line drawn through the lower end of the uterine sources, according to ICRU 38 report, received the maximum rectal doses in only 2 out of the nine patients $(22.2\%)$. Conclusion : In HDR ICR planning for conical cancer, optimization of the dose to the rectum by the computer-assisted planning system, using radiographs in simulation, is improper. This study showed that in vivo rectal dosimetry, using a diode detector during the HDR ICR, could have a useful role in quality control for HDR brachytherapy in cervical carcinomas. The importance of individual dosimeters for each HDR ICR is clear. In some departments that do not have the in vivo dosimetry system, the radiation oncologist has to find, from lateral fluoroscopic findings, the location of the rectal marker before each fractionated HDR brachytherapy, which is a necessary and important step of HDR brachytherapy for cervical cancer.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4595-4600
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• 2014

A geoid has great meaning as a vertical reference plane, and at this point when GPS measurement is vitalized, it is an important factor that makes level measurements with GPS possible. This study carried out GPS and leveling of newly created complex control points targeting Daejeon. The geoid for the precise area was built by calculating the plane location, elevation and the geoid of each reference point using GPS/Leveling. In addition, this study evaluated the potential of GPS leveling throughout the site calibration. The geoid for the precise area intervals of approximately 1.5km throughout the study was determined. The results highlight the possibility of leveling by estimating direct leveling performance and mean altitude deviation by less than 2cm. Based on the results, if a geoid model for the precise and wide area can be developed throughout ongoing research, survey tasks that require elevation can be streamlined and the efficiency maximized.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.11
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• pp.1130-1137
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• 2009

This paper proposes a new clock routing design for suppressing clock harmonic effects in a Printed Circuit Board (PCB) for a terrestrial Digital Multimedia Broadcasting(DMB) system. Typical crystal reference frequencies that are widely used in DMB tuners are 16.384 MHz, 19.2 MHz, 24.576 MHz. When the high-order harmonic components of these reference frequencies fall near the RF channel frequencies, receiver sensitivity of the tuners is seriously degraded. In this work, we propose a new clock routing design in order to address the clock harmonic coupling issue. The proposed design incorporates two inductors for isolating the clock ground from the main ground, and adopts a new strip line-style routing instead of the conventional microstrip line style routing to minimize the overlap area with the main ground. As a result, the RF sensitivity of the T-DMB tuner is improved by 2 dB.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.409-409
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• 2022

환경부 홍수통제소의 경우는 전국단위의 강수량(지상, 레이더), 하천수위, 유사량 관측과 국부적으로 증발산량과 토양수분 관측이 이루어지고 있는 상황이며, 기상청 및 다른 공공기관도 각 목적에 맞게 수문기상관측이 이루어지나 유역(또는 지역) 단위의 물순환 과정(강우량, 유출량, 증발산량, 지하수함양량, 토양수분량 등 포함)을 규명하는 조사·연구는 매우 미비한 실정이다. 개별적인 물순환 성분별 수문조사에서 벗어난 전체적인 관점을 고려한 유역단위의 물순환 과정을 규명하는 것은 매우 중요하다. 즉 물순환 성분별 명확한 수문량 산정 결과는 수자원 개발과 물환경 보전에 중요한 정보를 제공할 수 있다. 따라서 물순환 성분별 명확한 분석을 위해서는 중·소규모 유역 단위를 대상으로 지속적이고 신뢰성 있는 자료의 획득과 축적이 중요하므로 중·소규모 유역 단위의 대표성 있는 시험유역의 운영은 매우 의미가 있다고 볼 수 있다. 본 논문에서는 한국건설기술연구원에서 운영하는 설마천 유역(전적비교 수위관측소 기준, 유역 면적 8.48km², 유로연장 5.59km, 유로경사 2.15%, 경기도 파주시 적성면 소재)의 2021년 수문관측자료를 이용하여 지표수 물순환 성분인 강우량, 하천유출량, 증발산량을 산정하였다. 기본 관측자료인 강우량은 각 지점강우량의 관측자료의 비교·검토 등 품질관리를 통해 자료를 확정하고 유역평균강우량을 산정하였다. 하천수위는 기준수위표와의 검토를 통해 자료를 확정하였으며, 하천유출량은 기존의 유량측정성과와 단면검토를 통해 수위-유량관계곡선식을 개발하고, 확정된 수위자료를 적용하여 산정하였다. 그리고 증발산량은 유역인근 2개 관측소(동두천 파주)의 기상관측자료를 이용하여 잠재증발산량을 산정하여 추정한 값이며, 그 외 지하수 함양량은 관측 지하수위자료의 결측으로 산정에서 제외하였다. 각 물순환 성분별로 생성된 2021년의 설마천 유역(전적비교 수위관측소 기준)의 총강우량은 1,103.6mm이며, 하천유출량은 620.1mm(총강우량 대비 56.2%), 실제증발산량(잠재증발산량 추정값)은 443.0mm(40.1%)이며, 그 외는 유역 손실량이다. 이와 같이 산정된 물순환 성분별 자료는 유역의 물순환 과정 규명을 위한 기초자료로 매우 유용하게 활용될 수 있으며, 유역 물관리를 위한 의사결정 과정에 중요한 역할을 할 수 있을 것으로 기대된다.

• Korean Journal of Optics and Photonics
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• v.34 no.3
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• pp.117-123
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• 2023

The size of an optical surface can significantly affect the performance of an optical system, and high spatial frequency errors have a greater impact. Therefore, it is crucial to measure the surface figure error with high frequency. To address this, a new method called rotational prism stitching interferometer (RPSI) is proposed in this study. The RPSI is a type of stitching interferometer that enhances spatial resolution, but it differs from conventional stitching interferometers in that it does not require the movement of either the mirror tested or the interferometer itself to obtain sub-aperture interferograms. Instead, the RPSI uses a beam expander and a rotating Dove prism to select particular sub-apertures from the entire aperture. These sub-apertures are then stitched together to obtain a full-aperture result proportional to the square of the beam expander's magnification. The RPSI's effectiveness was demonstrated by measuring a 40 mm diameter spherical mirror using a three-magnification beam expander and comparing the results with those obtained from a commercial interferometer. The RPSI achieved surface testing results with nine times higher sampling density than the interferometer alone, with a small difference of approximately 1 nm RMS.

• Journal of agricultural medicine and community health
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• v.47 no.3
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• pp.166-180
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• 2022

Objective: This study evaluated the effects of a non-face-to-face obesity management program, implemented during the pandemic. Methods: The non-face-to-face obesity management program used the Intervention mapping protocol (IMP). The program was put into effect over the course of eight weeks, from September 14 to November 13, 2020 in 48 overweight and obese adults, who applied to participate through the Daegu Citizen Health Support Center. Results: IMP was first a needs assessment was conducted; second, goal setting for behavior change was established; third, evidence-based selection of arbitration method and performance strategy was performed; fourth, program design and validation; fifth, the program was run; and sixth, the results were evaluated. The average weight after participation in the program was reduced by 1.2kg, average WC decreased by 3cm, and average BMI decreased by 0.8kg/m² (p<0.05). The results of the health behavior survey showed a positive improvement in lifestyle factors, including average daily intake calories, fruit intake, and time spent in walking exercise before and after participation in the program. A statistically significant difference was seen (p<0.05). The satisfaction level for program process evaluation was high, at 4.57±0.63 point. Conclusion: The non-face-to-face obesity management program was useful for obesity management for adults in communities, as it enables individual counseling by experts and active participation through self-body measurement and recording without restriction by time and place. However, the program had some restrictions on participation that may relate to the age of the subject, such as skill and comfort in using a mobile app.

• Conservation Science in Museum
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• v.25
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• pp.1-8
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• 2021

This study investigated White Porcelain Water Dropper with Openwork Lotus Scroll Design and Eight Trigram Design in Cobalt-blue Underglaze (hereinafter, the "water dropper") in the collection of the National Museum of Korea using computed tomography (CT). A replica was produced to examine both the structure and its original production method. The CT scanning identified no joint lines or pores in the clay, which suggests that the body (the lower part of the water dropper) was shaped in a single piece using a mold and was then matched with a mold-formed lid (the upper part of the water dropper). The inner container of the body portion was roughly trimmed with a bamboo knife so that its upper surface could be securely attached to the bottom of the lid and prevent any leakage in the joined surface. It appears that the inner container for storing water was made first in a cylindrical shape that met the unit of quantity used at the time and could be easily formed by molding. It was transformed into a trapezoid shape during the process of combining it with the lid. A cylindrical inner container was reproduced using silicon 3D printing to compare its capacity with that of the original inner container. The comparison revealed that the reproduced container had a capacity of 152.5㎖, whereas the original container holds approximately 168.6㎖, a figure similar to three hop (around 174㎖) in Joseon-period units of quantity. Since the capacity of the cylindrical inner container corresponds to a known measure from the late Joseon dynasty, it is likely that the water dropper was originally produced to contain a cylindrical inner container.