• 한국전산구조공학회논문집
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• 제28권6호
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• pp.659-666
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• 2015

본 논문에서는 콘크리트 구조물의 층상박리균열 위에서의 손상탐지에 효율적인 충격반향기법에 대해 영향을 끼치는 다양한 영향요소들에 대한 분석을 수행하였다. 충격반향기법에서의 균열 가시화를 위해 층상박리균열위의 동적거동 및 두께를 나타내는 휨 모드 및 충격반향모드(두께 모드)에 영향을 끼치는 균열의 폭/두께(a/h) 비, 균열위의 상대적 가진 점, 측정 점의 위치 등의 시험설정 변수 등을 매개변수적 유한요소해석을 통하여 조사하였다. a/h비는 2보다 클 경우 휨 모드가 지배적이었으며 작을 경우 두께 모드가 지배적이었다. 또한 가진 점, 측정 점 중 어느 하나만 균열 위에 존재할 때도 휨 모드가 지배적이었으며 균열 밖의 범위의 건전한 영역에는 가진 점, 측정 점이 모두 위치하여야 두께 모드가 지배적이었다.

• 한국철도학회논문집
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• 제20권5호
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• pp.683-691
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• 2017

유라시아 지역으로 화물을 효과적으로 운송하기 위한 방안을 마련하기 위하여 TCR, TSR 등 국제철도와 해운을 이용한 운송현황을 서로 비교할 필요가 있다. 본 연구에서는 유라시아 국제운송로의 이용현황을 살펴보고 주 운송수단으로 이용되는 철도와 해상 간의 운송수단선택 실태를 분석하고자 하였다. 분석 자료는 유라시아 지역 운송을 담당하는 국제물류업체를 대상으로 수행된 SP조사 자료를 활용하였다. 유라시아 운송수단 선택특성을 분석한 결과, 유라시아 지역으로 화물 운송시 운송시간과 운송비용에 따라서 철도와 해운 간의 경쟁관계가 있음을 알 수 있었다. 또한 지역별로 해상과 철도로의 접근용이성에 따라 수단선택특성이 상이한 것을 알 수 있었다. 향후 유라시아 지역의 다양한 국제운송로를 효과적으로 이용하기 위한 방안을 모색하는데 본 연구결과가 활용될 수 있을 것으로 판단된다.

• Current Optics and Photonics
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• 제6권2호
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• pp.143-150
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• 2022

Anti-resonant hollow-core photonic crystal fiber (AR-HCF) has unique advantages, such as low nonlinearity and high damage threshold, which make it a promising candidate for high-power laser delivery at distances of tens of meters. However, due to the special structure, optical properties such as mode-field profile and bending loss of hollow-core fibers are different from those of solid-core fibers. These differences have limited the widespread use of AR-HCF in practice. In this paper we conduct numerical analysis of AR-HCFs with different structural parameters, to analyze their influences on an AR-HCF's optical properties. The simulation results show that with a 23-㎛ air-core diameter, the fundamental mode profile of an AR-HCF can well match that of the widely used Nufern's 20/400 fiber, for nearly-single-mode power delivery applications. Moreover, with the ratio of cladding capillary diameter to air-core diameter ranging from 0.6 to 0.7, the AR-HCF shows excellent optical characteristics, including low bending sensitivity while maintaining single-mode transmission at the same time. We believe these results lay the foundation for the application of AR-HCFs in the power delivery of high power fiber laser systems.

• 제어로봇시스템학회논문지
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• 제18권7호
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• pp.650-657
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• 2012

An effective dual-mode camera system(a passive wide-angle camera and a pan-tilt-zoom camera) is proposed in order to improve the performance of visual surveillance. The fixed wide-angle camera is used to monitor large open areas, but the moving objects on the images are too small to view in detail. And, the PTZ camera is capable of increasing the monitoring area and enhancing the image quality by tracking and zooming in on a specific moving target. However, its FOV (Field of View) is limited when zooming in on a specific target. Therefore, the cooperation of wide-angle and PTZ cameras is complementary. In this paper, we propose an automatic initial set-up algorithm and coordinate transform method from the wide-angle camera coordinate to the PTZ one, which are necessary to achieve the cooperation. The automatic initial set-up algorithm is able to synchronize the views of two cameras. When a moving object appears on the image plane of a wide-angle camera after the initial set-up positioning, the obtained values of the wide-angle camera should be transformed to the PTZ values based on the coordinate transform method. We also develope the PTZ control method. Various in-door and out-door experiments show that the proposed dual-camera system is feasible for the effective visual surveillance.

• 대한물리치료과학회지
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• 제18권3호
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• pp.87-92
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• 2011

Purpose : The purpose of this study is to have examined the influence on the blood circulation by comparing the differences between stimulating the sympathetic ganglion and the muscle group among the stimulation variables in interferential current stimulation and to have found out the most effective stimulating mode for the improvement the peripheral blood circulation in the interferential current stimulation. Method : The subjects of the study is the men and women in the twenties, who are in great condition and have no pathological report for the blood circulation influence. The intensity of the inferential current stimulation is the medium degree, 100 bps constant current, which is the comfort and overt degree to confirm the muscle contraction. The areas stimulated by the interferential current stimulation are the stellate ganglion area in the seventh cervical vertebrae and the forearm muscle area. The stimulating time is twenty minutes long. After stimulating the two areas, the change of the blood circulation has been measured. Results : Both stimulating the sympathetic ganglion and stimulating the muscle, before and after interferential current stimulation, we have seen that the amount of blood circulation was increased significantly and statistically in both two groups(p<.01) and that the amount of blood circulation was increased significantly and statistically in the case of stimulating the sympathetic ganglion(p<.01). Conclusion : The conclusion we received that inferential current stimulation had the clear influence on increasing the peripheral blood circulation. And stimulating the sympathetic ganglion area is more effective than stimulating muscle area directly.

• 멤브레인
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• 제25권1호
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• pp.7-14
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• 2015

본 연구에서는 MBR 내에 침지된 분리막 오염을 평가하기 위하여 운전시간에 따른 막간차압(TMP)을 측정하였다. 유효 막면적이 $0.02m^2$이고 공칭 세공크기가 $0.15{\mu}m$인 정밀여과용 평막 모듈을 MLSS 5,000 mg/L인 활성슬러지 용액에 침지시켰다. 운전/휴직(R/S) 및 사인파형 투과유속 연속운전(SFCO) 방식에 따른 TMP를 비교하기 위하여 동시에 투과 실험을 수행하였다. SFCO 운전방법에 따른 TMP는 R/S에 비하여 최대 93% 낮게 유지되었으며 투과유속이 증가함에 따라서 TMP 감소 효과는 줄어들었다. 또한 응집제인 $FeCl_3$를 활성슬러지 용액에 500 mg/L 농도로 주입시키면 SCFO 운전방식의 경우, 투과 운전시간을 5배 이상 증가시켜도 한계 운전 TMP인 55 kPa의 40% 미만으로 유지됨을 확인할 수 있었다.

• 한국음향학회지
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• 제41권6호
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• pp.691-697
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• 2022

직류 계전기는 전기자동차의 하나의 부품으로 간헐적으로 고주파수 소음이 710 Hz ~ 730 Hz의 주파수 범위에서 전기적 부하에 의해 발생한다. 고정접점과 가동접점 사이에서 발생하는 전자 반발력이 가동접점과 접압 스프링을 진동시키고, 그 진동으로 가동접점과 접압 스프링에 공진이 발생하여 고주파수 소음이 발생한다. 본 논문에서는 수치해석 및 실험을 통하여 고주파수 소음의 원인을 규명하고, 소음을 제거하는 방안을 제시하였다. 710 Hz ~ 730 Hz의 주파수 범위에서 가동접점은 고정접점과의 2개의 접촉점을 기준으로 회전하는 공진모드가 발생한다. 따라서 해당 여기서 제안한 방법은 공진모드를 제거하기 위해 가동접점의 구조를 2점 접촉구조 방식에서 3점 접촉구조 방식으로 변경하는 것이다. 3점 접촉구조를 적용함에 따라 공진모드가 제거되는 것을 수치해석으로 확인하였고, 실험적으로도 고주파수 소음이 발생하지 않는 것을 확인하였다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제8권3호
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• pp.262-276
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• 2016

Generally, the Safety Integrity Level (SIL) of a subsea Blowout Preventer (BOP) is evaluated by determining the Probability of Failure on Demand (PFD), a low demand mode evaluation indicator. However, some SIL results are above the PFD's effective area despite the subsea BOP's demand rate being within the PFD's effective range. Determining a Hazardous Event Frequency (HEF) that can cover all demand rates could be useful when establishing the effective BOP SIL. This study focused on subsea BOP functions that follow guideline 070 of the Norwegian Oil and Gas. Events that control subsea well kicks are defined. The HEF of each BOP function is analyzed and compared with the PFD by investigating the frequency for each event and the demand rate for the components. In addition, risk control options related to PFD and HEF improvements are compared, and the effectiveness of HEF as a SIL verification for subsea BOP is assessed.

• Advances in pediatric surgery
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• 제5권1호
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• pp.69-74
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• 1999

Condyloma acuminata, an uncommon disease m the pediatric patients, is being reported with increasing frequency in both adults and children. During the last 10 years, we managed 11 children with condyloma acuminata of the anogenital area. The patients' age at presentation varied from 9 months to 11 years, and boys outnumbered girls by a ratio of 2 : 1. The lesions were found in the perianal area in 9 patients and the genital area in 2. No history of sexual contact or abuse could be elicited. Although the exact mode of transmission of human papillomavirus(HPV) couldn't be defined, maternal-infant transmission at birth and close nonsexual family contact were the main possible causes of HPV infection in our patients. Our experience suggest that fulguration of the warts and concomitant excision with scissors of the larger lesions are the most satisfactory method of treatment in children. However, condyloma acuminata have high recurrence rate despite these treatments. Viral typing and careful epidemiological investigation on a larger series of patients may clarify the causative factors and effective modalities of treatment in childhood anogenital condyloma acuminata.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권4호
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• pp.614-624
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• 2013

The resonance power buoy is a convincing tool that can increase the extraction efficiency of wave energy. The buoy needs a corresponding draft, to move in resonance with waves within the peak frequency band where wave energy is concentrated. However, it must still be clarified if the buoy acts as an effective displacement amplifier, when there is insufficient water depth. In this study, the vertical displacement of a circular cylinder-type buoy was calculated, with the spectrum data observed in a real shallow sea as the external wave force, and with the corresponding draft, according to the mode frequency of normal waves. Such numerical investigation result, without considering Power Take-Off (PTO) damping, confirmed that the area of the heave responses spectrum can be amplified by up to about tenfold, compared with the wave energy spectrum, if the draft corresponds to the peak frequency, even with insufficient water depth. Moreover, the amplification factor of the buoy varied, according to the seasonal changes in the wave spectra.