• Aerospace Engineering and Technology
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• v.10 no.1
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• pp.30-38
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• 2011

Structural effects of several geometric parameters such as shroud thickness, edge roundness and fillet radius of turbopump turbine blade were investigated throughout transient finite element analyses. Usually shroud is inserted to increase aerodynamic efficiency, but blocks deformation of blades. Therefore it can increase stress level in a structural point of view. Likewise, edge roundness and fillet between blades are also parameters where aerodynamics and structural mechanics should compromise. In this study, overall stress levels according to the geometric parameters were thoroughly investigated and the results could be utilized to determine optimal geometries.

• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.289-293
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• 2001

A metal capillary splice fiber-optic sensor was fabricated for use as an intensity-based macro-bending sensor. As the radius of curvature due to the macro-bending decreases, the angular misalignment of the fiber ends inside the metal capillary increases, i.e., the coupling efficiency of the fiber splice is reduced. Thus, macro-bending can be detected by the measurement of the reduction of transmitted power. The detectable range of macro-bending. was measured approximately from 20 mm to 85 mm. The center wavelengths of the fiber Bragg gratings are 1543.3 nm and 1549.5 nm, respectively. The maximum bending loss of this sensor was measured about -11.92 dB. Using this metal capillary spliced fiber sensor and fiber Bragg gratings, macro-bending detection has been demonstrated, and it is shown to have potential for multi-point macro-bending sensors. nsors.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.5 no.1
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• pp.143-154
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• 1998

Background : There have been very few studies conducted on the number and type of microorganisms that remain on the ring finger after handwashing. This study was performed to investigate whether there were changes and differences in the type and number of microorganisms on the ring finger before and after handwashing. Method : The subjects of the study were 15 MICU and SICU staff nurses who were wearing rings. I swabbed two different fingers of the same hand with cotton balls. One finger which had a ring and the other with no ring. I swabbed the fingers of each subject three times(before handwashing, after handwashing with soap, and after handwashing with bethadine solution). After storing them for 48 hours in an incubator, I sent them to the laboratory and recorded the culture results. Results : There was no difference in the type of microorganism, but a major difference in the number of the microorganisms that existed on the finger ring. The results showed that there were much more microorganisms on the ring fingers than on the fingers that did not have rings both before and after handwashing. This tendency was consistent regardless of the handwashing agent. I therefore recommend that all nursing staff who work in general nursing units, as well as nurses who work in the ICU, remove their rings when taking care of the patients.

• Journal of Korean Society of Forest Science
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• v.96 no.4
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• pp.448-454
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• 2007

Mathematical models for predicting the ground and semi-ground skidding force have been developed. The skidding force is expressed as a function of log geometry, total weight and coefficient of skidding. The coefficient of skidding was determined under field tests. The validity of the model developed was examined by comparing the predicted and measured skidding forces. Calculated ground skidding force, using the model developed can be predicted well with that measured experimentally. The semi-ground skidding force calculated from the model, however, does not predict well due to its confined conditions experimentally.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.179-179
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• 2000

음극의 크기에 따라 발생된 전자빔 전류가 도파관 영역에서 공간 전하 한계 전류를 초과할 경우 형성되는 가상 음극 (Virtual Cathode)을 이용한 축 방향으로의 고출력 마이크로파 발생 및 진단에 관한 연구를 수행하였다. 먼저 실험에 앞서 전산모사를 통해 결과를 예측하고 실험을 통해 확인하는 순으로 하였다. 전산 모사는 2-1/2차원 Partical-In-Cell(PIC) 코드인 "MAGIC"을 사용하여 축 방향으로 진행하는 새로운 개념의 가상 음극발진기를 모사하고, 정확한 경과를 얻기 위해 강렬한 상대론적 전자빔 발생 장치인 "천둥"( 최대 전압 600kV, 최대 전류 70KA, 60ns)을 사용하여 전산 모사에 넣어줄 전류값을 얻었다. 음극의 반지름이 2.5cm 일 때 전파되는 최대 출력이 약 800MW인 마이크로파가 발생되었고, 이때 출력변환 효율이 약 30%임을 전산모사를 통하여 알 수 있었다. 또한 전파하는 전기장의 축방향 성분(Ez)의 반지름 방향에 대한 분포 특성을 통하여 주된 전파 모드가 TM01와 그 상위모드의 조합으로 이루어졌음을 알았고 이때 기대되는 동작 진동수는 5~7 GHz임을 전산 모사 결과로부터 알 수 있었다. 실험을 통해서도 음극의 크기가 2.5cm 때, 최대 출력이 약 520MW인 마이크로파를 발생하였고, 이 때 출력 변환 효율은 약 8%이고, 방전 사진을 통해서 주된 동작 모드가 TM01와 그 상위모드의 조합으로 이루어졌음을 알았고, 이때 주된 출력 진동수는 5~6 GHz임을 알 수 있었다.는 5~6 GHz임을 알 수 있었다.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.2
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• pp.83-90
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• 2018

This study was conducted to investigate the living environment of semi-basement housing units in multi-household houses. It analyzed measurements of temperature and humidity obtained from the housing units. For this study, temperature and humidity sensors were installed in 10 semi-basement housing units to measure interior temperature and humidity for 13 months. A survey was conducted to get information about the occurrence of dew condensation and mildew and to investigate residents' satisfaction level with the residential environment. According to the result, all the housing units under study had dew condensation and mildew. The average summer temperature of the 10 housing units was $27.84^{\circ}C$, and average humidity was 64.91%RH, while the average winter temperature was $20.6^{\circ}C$, and the average humidity was 40.12%RH. Depending on the condition of each housing unit, deviation was big. Residents' average level of satisfaction with the living condition was 2.03 which shows a low satisfaction (on a scale of 1-5 with 5 being completely satisfied.).

• The Journal of Korean Society for Radiation Therapy
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• v.32
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• pp.53-59
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• 2020

Purpose: The purpose of this study is to compare and analyze the difference between the MLC log file-based software (Mobius) and the conventional phantom-ionization chamber (ArcCheck) dose verification method according to the change of target volume. Material and method: Radius 0.25cm, 0.5cm, 1cm, 2cm, 3cm, 4cm, 5cm, 6cm, 7cm, 8cm, 9cm, 10cm with a Sphere-shaped target Twelve plans were created and dose verification using Mobius and ArcCheck was conducted three times each. The irradiated data were compared and analyzed using the point dose error value and the gamma passing rate (3%/3mm) as evaluation indicators. Result: Mobius point dose error values were -9.87% at a radius of 0.25cm and -4.39% at 0.5cm, and the error value was within 3% at the remaining target volume. The gamma passing rate was 95% at a radius of 9cm and 93.9% at 10cm, and a passing rate of more than 95% was shown in the remaining target volume. In ArcCheck, the average error value of the point dose was about 2% in all target volumes. The gamma passing rate also showed a pass rate of 98% or more in all target volumes. Conclusion: For small targets with a radius of 0.5cm or less or a large target with a radius of 9cm or more, considering the uncertainty of DQA based on MLC log files, phantom-ionized DQA is used in complementary ways to include point dose, gamma index, DVH, and target coverage. It is believed that it is desirable to verify the dose delivery through a comprehensive analysis.

• Journal of The Korean Society of Grassland and Forage Science
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• v.6 no.2
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• pp.97-102
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• 1986

This investigation was carried out to find out the succession of Carex ferruginea community by PK-fertilization and sheep grazing. The area covered with Caricetum ferrugineae and located at the Bavarian Alps in the southern part of Germany. 1. By the experimental conditions was changed the plant community of Caricetum ferrugineae, however, the influence of PK-fertilization was much more effective than that of sheep grazing. 2. As the species of Carex ferruginea, Melica nutans, Brachypodium sylvaticum, Calamagrostis varia were weak the absorptive ability of nutritive subatance, they almost disappeared due to PK-fertilization. On the other hand, grasses and legumes (Festuca rubra, Agrostis tenuis, Poa trivialis, Trifolium repens) increased by PK-fertilization distinctly. 3. The life forms of plant community at the experimental area covered with Hemicrytophytes of 55% and Geophytes of 40%. But by the PK-fertilization with sheep grazing increased their life forms Hemicryptophytes by 19% and Geophytes decreased by 31%, but in case the sheep grazing without fertilization increased Geophytes by 11% and Hemicryptophytes decreased by 12%. 4. The plant community of Caricetum ferrugineae before the experiment was successived into Festuco-Cynosuretum by PK-fertilization with sheep grazing.

• The Journal of the Korea institute of electronic communication sciences
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• v.8 no.12
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• pp.1883-1890
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• 2013

Location detection technology (LDT) is one of the core techniques for location based service (LBS) in wireless communication for improving resource management and quality of services. The location of a mobile station (MS) is estimated using the time of arrival (TOA) technique based on three circles with centers corresponding to coordinates of three base stations (BSs) and radius corresponding to distances between MS and BSs. For accurately estimating the location of MS, three circles should meet at a point for the trilateration method, but they generally do not meet a point because the radius is increased depending on the number of time delay for estimating the distance between MS and BS and the carrier frequency. The increased three circles intersect at six points and the three intersection points among them should be generally placed close to coordinate of the location for the specific MS. In this paper, we propose the shortest distance algorithm for TOA trilateration method, to select three interior intersection points from entire six points. The proposed approach selects three intersection points with the shortest distances between coordinates of MS and intersection points and determines the averaged coordinate of the selected three points, as the location of the specific MS. We demonstrate the performance of the proposed algorithm using a typical computer simulation example.

• Journal of the Korean Geophysical Society
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• v.3 no.1
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• pp.67-74
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• 2000

Subsurface structure of the Bomun basin was studied along three survey tracks of Line-1, Line-2, and Line-3 using geomagnetic, radioactive, and seismic refraction methods. Abrupt changes found at 2.55 km west and 1.6 km east in the profile of magnetic anomaly along Line-1 are correlated with geologic boundary of the basin. Profiles of radioactive intensity also represent abrupt changes at 2.55 km west of Line-1 and at 1.9 km of Line-2. Cretaceous basement rock has relatively high magnetic anomaly of $200\;{\sim}\;500\;nT$ while sedimentary rocks of the Bomun basin have relatively low magnetic anomaly of $-100\;{\sim}\;+100\;nT$. Radioactive intensity also represents charateristic differences between Cretaceous basement and sedimentary rocks of the Bomun basin. Rocks of Cretaceous basement have lower radioactive intensity than the rocks of the Bomun basin. Magnetic anomaly of of the Bomun basin represents lowest anomaly in western part and increases gradullay toward east. This phenomenon is interpreted as a half graben structure dipping westward. Black shale known by previous studies near the western boundary has high magnetic anomalies and low radioactive intensity. This phenomenon provide a possibility of volcanic rock rather than black shale near the western boundary of the basin along Line-1. Sedimentary layers having velocities of 455 m/s, 1904 m/s, and 2662 m/s are developed to have westward dipping of $2.3^{\circ}$ in the central area of the Bomun basin. The result is consistent with a half-graben model dipping westward which were derieved from magnetic anomaly data.