• 구강회복응용과학지
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• 제33권1호
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• pp.42-46
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• 2017

부식이란 산성의 화학적 물질에 의한 치아 경조직의 손상으로 정의된다. 이에 대한 원인인 산성 음식, 약물, 작업환경 등의 외부적 원인과 위장관 장애에 의한 위산의 역류나 거식증에 의한 의도적 구토의 내부적 원인에 의해 발생된다. 이는 임상적 증상의 심각도에 따라 레진 충전, 라미네이트 수복 또는 전장관 수복으로 치료한다. 본 증례는 잦은 산성 과일의 섭취로 인한 전치부 순측 부식 및 거식증으로 인한 의도적 구토로 전치부 구개측 부식이 일어난 드문 상황에 대한 치료이다.

• 한국통신학회논문지
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• 제31권7C호
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• pp.743-754
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• 2006

본 논문에서는 두 개의 다른 밀리미터 파장을 적용하는 광전계통의 구조 변경을 시도하고 신호 흡수나 환경적 간섭 왜곡에 취약한 싱글 빔(single beam) 레이저 방식의 단점을 보완한 듀얼 빔(dual beam) 방식의 레이저 레이더 시스템을 제안한다. 본 논문에서 제한 한 듀얼 빔 방식 레이더 시스템은 적은 신호 검파의 신뢰성 측면에서 통계적이며 분석적인 방법으로 제안하여 시스템의 우수성을 입증하고 AWGN 배경 잡음과 흡수 또는 간섭에 의해 레이저 신호의 왜곡이 발생하는 채널환경에서 시뮬레이션을 수행함으로써 신호 검파의 신뢰성 향상이 가능하다는 분석적 결과에 대한 정량적 재검증을 한다.

• Journal of Radiation Protection and Research
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• 제40권3호
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• pp.147-154
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• 2015

The scatter photons and photoneutrons from high energy photon beams (more than 10 MV) will increase the undesired dose to the patient and the staff working in linear accelerator room. This undesired dose which is found at out-of-field area can increase the probability of secondary malignancy. The purpose of this study is to determine the equivalent dose of scatter photons and neutrons generated by 3 different treatment techniques: 3D-conformal, intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT). The measurement was performed using two types of the optically stimulation luminescence detectors (OSL and OSLN) in the Alderson Rando phantom that was irradiated by 3 different treatment techniques following the actual prostate cancer treatment plans. The scatter photon and neutron equivalent dose were compared among the 3 treatments techniques at the surface in the out-of-field area and the critical organs. Maximum equivalent dose of scatter photons and neutrons was found when using the IMRT technique. The scatter neutrons showed average equivalent doses of 0.26, 0.63 and $0.31mSv{\cdot}Gy^{-1}$ at abdominal surface region which was 20 cm from isocenter for 3D, IMRT and VMAT, respectively. The scattered photons equivalent doses were 6.94, 10.17 and $6.56mSv{\cdot}Gy^{-1}$ for 3D, IMRT and VMAT, respectively. For the 5 organ dose measurements, the scattered neutron and photon equivalent doses in out of field from the IMRT plan were highest. The result revealed that the scatter equivalent doses for neutron and photon were higher for IMRT. So the suitable treatment techniques should be selected to benefit the patient and the treatment room staff.

• Safety and Health at Work
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• 제8권2호
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• pp.183-188
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• 2017

Background: Recommendations have been proposed for minimum aerobic fitness among firefighters but it is unclear if those criteria relate to performance on the fireground. Less fit individuals fatigue more quickly than fit individuals when working at comparable intensity and may have gait changes, increasing risk of falls. We evaluated the effect of fatigue during a live burn evolution on gait parameters and functional balance comparing them to aerobic fitness levels. Methods: A total of 24 firefighters had gait and balance tested before and after a live burn evolution. Data were stratified by aerobic fitness of greater/less than 14 metabolic equivalents (METs). Results: Analysis of gait cycles measurements before and after the live burn evolution revealed that single leg stance, cycle, and swing time decreased (p < 0.05) but there were no differences in the other measures. There were no differences in time to complete the functional balance test, or errors committed before or after a live burn evolution. When firefighters were sorted by fitness level of 14 METs, there were no differences for errors or time before or after the live burn evolution. Balance data were analyzed using a linear regression. Individuals with lower fitness levels required more time to complete the test. Conclusion: A 14-MET criterion failed to distinguish gait or balance characteristics in this group. However, less fit firefighters did require more time to complete the balance test (p = 0.003). Aerobic fitness alone does not predict gait changes among firefighters following a live burn evolution but does appear to influence functional balance.

• 한국물환경학회지
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• 제21권1호
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• pp.29-33
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• 2005

In order to recycle the waste material and to develop the thickening unit of waste activated sludge from wastewater treatment facilities, the filtration bio-reactor equipped with a shadow mask filter module was employed for this work from which the operating properties and parameters were drawn. The sludge thickening and filtration unit is made of cylindrical acryl tank(12cm i.d. ${\times}$ 58cm height: working volume of 6L), where the flat-sheet type of shadow mask filter module(pore size: 220~250um, opening area: 34.8~39.6%) was installed and the effluent was withdrawn from the effluent port at the lowest point of the reactor, and the filtration was performed only by the hydraulic pressure. For evaluating the operating performance of this reactor, some parameters such as the solid-liquid separation of different biomass concentrations, the water quality of filtrate, the aeration cleaning time and the cleaning effect were investigated. Depending on the MLSS concentrations, the different time to withdraw 3L of filtrate was required in which the longer filtration time was necessary for the higher MLSS concentrations caused by the thicker formation of cake layer: 40 minutes for 5,000 mg/L, 70 minutes for 10,000 mg/L and 100 minutes for 15,000 mg/L, where the concentrations of SS were 8.9, 6.7 and 6.5 mg/L, respectively. Under the same operating conditions (the intensity of aeration cleaning: 80 L/min, MLSS: 10,000 mg/L), the proper aeration cleaning time was revealed 30 seconds, and the stable formation of cake layer was in the range of 10 to 15 minutes. Therefore, the shadow mask considered as a waste material can be of use as a filter material for the sludge thickening system.

• 대한기계학회논문집A
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• 제35권4호
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• pp.401-407
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• 2011

본 연구에서는 AZ31B 마그네슘 합금 평판 연마에 제 2세대 자기연마공정을 적용하고 실험계획법을 통해 공정인자들의 특성을 평가하였으며, 2차 반응표면모델을 이용한 표면거칠기 예측모델을 개발하였다. 비자성체 재료의 기존 자기연마 공정에서는 재료의 표면에서 자기력이 낮아 표면거칠기의 향상에 효율이 낮은 단점을 가진다. 이를 보완하기 위하여 전자석 배열을 이용한 자기력 테이블을 자기연마 공정에 적용하여 비자성체 표면의 자기력을 향상시킬 수 있었다. 이러한 시스템을 제 2세대 자기연마라 일컫고, 실험계획법에 따른 공정 인자 평가 결과, 자기력 테이블의 전자석 세기가 AZ31B 평판의 표면 거칠기 향상에 가장 큰 영향을 가지고 있음을 확인했다. 또한 자기력 테이블과 공구의 회전속도에 따른 반응표면모델을 개발함으로써 마그네슘 자기연마 공정의 효율성을 높일 수 있었다.

• 대한기계학회논문집B
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• 제37권9호
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• pp.799-805
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• 2013

본 논문에서는 나노유체를 사용한 평판형 집열기의 효율을 예측하기 위한 이론적인 연구를 수행하였다. 평판형 태양열 집열기 내부의 온도분포에 관한 해석적 해를 구하기 위해 무차원화된 2 차원 열 확산방정식을 풀었으며, 이 과정에서 흡광계수와 복사강도는 파장에 독립적이라고 가정하였다. 이렇게 주어진 식을 바탕으로, 물-기반 단일벽 탄소나노혼 나노유체를 작동유체로 사용할 경우 나노입자의 부피비, 열손실의 크기, 집열기의 높이에 따른 무차원 온도분포를 파악해 보았다. 마지막으로 나노유체 기반 평판형 집열기의 효율을 예측해 본 결과 일정 형상조건 이내에서 나노유체 태양열 집열기가 기존 집열기 보다 높은 효율을 가질 수 있음을 파악하였다.

• Journal of Biosystems Engineering
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• 제30권4호
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• pp.210-219
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• 2005

This study was conducted to solve the problem of crawled spinach harvesting that had been mainly done by manpower on the outdoor fields during the winter season. Moreover, there are not enough workers available for farming at most of rural areas in Korea because farming is getting hard and the number of old-aged workers is increasing. In order to find appropriate methods of digging, picking and collecting of spinach, the tests were examined outdoors. A prototype was designed based on the results of the tests and then fabricated for digging, picking-up and then collecting in continuous operation for harvesting spinach planted in the outdoor fields. In the field test with the prototype, the vibration intensity transmitted to the driver by vibrating blade was low while the vibrating blade reduced digging power by $46\%$ compared to that of the fixed blade. The spinach loss was found to be as low as $0.7\%$ in the condition of digging depth of 40 mm, cam rotational velocity of 748 rpm, and blade amplitude of 16.5 m. The working performance of the prototype spinach harvester was found to be 3.8 hour/10a resulting in $96\%$ of labor saving and $85\%$ of operating cost compared to the conventional manual harvesting.

• 터널과지하공간
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• 제18권5호
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• pp.375-385
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• 2008

광미적치장 수문 분석은 강우에 의한 유출량 합과 배수처리량을 단순 비교하는 댐과 달리 지하 배수시설 뿐만 아니라 지상배수시설과 비상배수시설 등 여러 종류의 배수처리 시설이 복합적으로 운영되기 때문에 유출량과 배수량을 시공간적으로 비교하여야 한다. 본 연구에서는 이와 같이 다단계 배수시설로 구성된 구 상동광산의 신광미적치장의 배수처리 능력을 GIS 기법을 이용하여 분석하였다. 분석 결과, 배수시설이 정상 작동할 경우 100년 빈도 시간 확률강우량인 80.31 mm/hr의 강우강도로 1시간 동안 비가 내리더라도 범람의 위험성은 없는 것으로 예측되었다. 그러나 모든 배수시설이 작동하지 않는다면 총 강우량이 251.1 mm에 도달할 때 광미댐은 범람의 위험성이 있는 것으로 예측되었다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.220-220
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• 2011

The Ne-Xe plasmas in dense plasma-focus device with coaxial electrodes were generated for extreme ultraviolet (EUV) lithography. The influence of gas mixture ratio, Ne-Xe (1, 10, 15, 20, 25, 30, 50%) mixture gas, on EUV emission measurement, EUV intensity and electron temperature in the coaxially focused plasma were investigated. An input voltage of 4.5 kV was applied to the capacitor bank of 1.53mF and the diode chamber was filled with Ne-Xe mixture gas at a prescribed pressure. The inner surface of the cylindrical cathode was lined by an acetal insulator. The anode was made of tin metal. The EUV emission signal of the wavelength in the range of 6~16 nm has been detected by a photo-detector (AXUV-100 Zr/C, IRD). The visible emission line was also detected by the composite-grating spectrometer of the working wavelength range of 200~1100 nm (HR 4000CG). The electron temperature is obtained by the optical emission spectroscopy (OES) and measured by the Boltzmann plot with the assumption of local thermodynamic equilibrium (LTE).