하수처리장에서 수력학적 와류형 분리장치를 이용한 침사제거

염철민,신경무,박노연 대한상하수도학회 2004 상하수도학회지 Vol.18 No.2

여성요도구협착의 수술적 교정

오범석,김도완,오철규,노안식,박석산 白中央醫療院 2005 仁濟醫學 Vol.26 No.1

Objective: We describe various clinical presentations of female urethral meatal stricture, which may mimic other pelvic floor disorders and result in diagnostic delay. Diagnosis, management, and outcome results are reported Materials and Methods: We reviewed retrospectively 26 consecutive cases of female urethral meatal stricture. Patient characteristics, history, clinical presentation, symptom score, maximal flow rate, residual urine, diagnosis, management and short-term follow up are reported. Results: Mean patient age plus or minus standard deviation was 54 years. Most 21 (81%) cases were referred as diagnostic dilemmas with symptoms present for 1 month to 30 years. Mean interval between onset of symptoms to diagnosis was 5.8 years. The most common symptoms were residual urine sensation (77% of cases), frequency (54%), pelvic pain (46%), dysuria (46%), weak stream urine (27%), urgency (15%) and 17 patients (65%) have combined symptoms. 16 patients (62%) had been treated with oral and/or vaginal medication and/or psychotherapy. The female urethral meatal stricture was visible on physical examination in 21 patients (81%) and cystoscopy in 5 patients (19%). Of these visible urethral meatal stricture, 11 patients (45%) contained recurrent urinary tract infection, 9 patients (35%) contained urethral mucosal prolapse, 7 patients (27%) contained urethral diverticulum, and 3 patients (12%) contained stress urinary incontinence. 18 patients (69%) who has been treated with oral and/or vaginal medication or psychotherapy was not successfully improved. Treatment consist of urethral meatal excision and/or everted urethral mucosal excision and/or urethral diverticulum excision and/or anti-incontinence surgery when indicated. Subsequently 24 patients (92%) had improved symptom score, but 2 patient was not changed. In 9 patients new symptom developed. Conclusions: Female urethral meatal stricture have several urinary symptoms and may mimic other pelvic floor disorders. This condition should be considered in women with frequency, residual urine sensation, pelvic pain, dysuria and etc. Medical treatment is not sufficient but surgical treatment is usually simple, safe and effective in alleviation associated symptoms.

Improvement of loading/unloading performance using control input position and considering disk vibration characteristics

Park, Kyoung-Su,Chun, Jeong-Il,Lee, Yong-Hyun,Park, No-Cheol,Yang, Hyun-Seok,Park, Young-Pil IEEE 2005 IEEE transactions on magnetics Vol.41 No.2

Loading/unloading (L/UL) dynamic characteristics are affected by various operating parameters, such as L/UL speed, disk speed, disk vibration, and so on. The effects of these parameters on L/UL performance are investigated experimentally using an acoustic emission (AE) sensor, an in-plane laser Doppler vibrometer (LDV), and a vertical LDV. The experimental data shows that during the loading of the slider, the contact probability is lower for low L/UL speeds. The frequencies of slider-disk contact are lower for low disk rpm during the loading process, whereas in the unloading process the contact probability is lower for high disk rpm. The effects of disk vibration on the L/UL process are also studied, and we have found that the relative gap and slider-disk velocity between the disk and ramp affect the contact events in the L/UL process. During 1000 unloading cycles, most noncontact events occurred near the region of the maximum ramp gap during the loading process. During unloading, most of the contacts between the slider and disk occurred at the minimum relative speed. Slider-disk contact rarely occurred at the maximum relative unloading speed. The noncontact region tends to expand with higher disk speeds during the unloading process. This paper proposes a method to control the unloading input position to improve L/UL performance. By controlling the unloading instant based on the disk vibration characteristics, we can significantly reduce the number of slider-disk contacts.

POSITION AND VIBRATION CONTROL OF 2 D.O.F. FLEXIBLE MANIPULATOR WITH ARTIFICIAL PNEUMATIC MUSCLE ACTUATORS

No-Cheol Park,Hyung-Wug Park,Hyun-Seok Yang,Young-Pil Park 한국소음진동공학회 1997 한국소음진동공학회 국제학술대회논문집 Vol.1997 No.1

Repetitive controller design for minimum track misregistration in hard disk drives

Park, Sung-Won,Jeong, Jun,Yang, Hyun Seok,Park, Young-Pil,Park, No-Cheol IEEE 2005 IEEE transactions on magnetics Vol.41 No.9

Repetitive control is a widely used technique for the compensation of repeatable error in systems that contain rotating mechanisms or repeat a trajectory. Generally, it includes delay chains and a low-pass filter in the positive feedback loop, which generate a periodic signal. The controller has typically been implemented in a plug-in fashion and designed heuristically with the simplest form of the filter. However, this design approach is somewhat ambiguous in the selection of controller parameters because of its influence over nonharmonic frequencies. Also, it leaves the possibility for further improvement. This paper presents an improved design method for the repetitive controller that provides minimum track misregistration (TMR) in a hard disk drive (HDD). For TMR prediction, the method identifies disturbances acting on an HDD and estimates servo performance, using the identification result. We have confirmed the identification and estimation procedure through experiments. In our method, first the basic tracking controller is designed and later the repetitive controller is designed in conjunction with a Q filter. A cost function based on Parseval's theorem, reflecting the servo performance as TMR, is defined. Then the servo performance is estimated from the identified disturbance, and the plant and designed controller's frequency response are modified as necessary by changing the parameters of the controller, whose optimization is carried out with a commercial nonlinear optimization tool. The design strategy facilitates the controller design by providing an accurate estimation for the attainable servo performance and design criteria under the optimization framework.

Position and Vibration Control of 2 D. O. F Flexible Manipulator with Artficial Pneumatic Muscle Actuators

No Cheol Park,Hyung Wug Park,Hyun Seok Yang,Young Pil Park 대한기계학회 1997 Asia-Pacific Vibration Conference Vol.1 No.1

MODAL CHARACTERISTIC ANALYSIS OF THE APR1400 NUCLEAR REACTOR INTERNALS FOR SEISMIC ANALYSIS

Park, Jong-Beom,Choi, Youngin,Lee, Sang-Jeong,Park, No-Cheol,Park, Kyoung-Su,Park, Young-Pil,Park, Chan-Il Korean Nuclear Society 2014 Nuclear Engineering and Technology Vol.46 No.5

Reactor internals are sensitive to dynamic loads such as earthquakes and flow induced vibration. Thus, it is essential to identify the dynamic characteristics to evaluate the seismic integrity of the structures. However, a full-sized system is too large to perform modal experiments, making it difficult to extract data on its modal characteristics. In this research, we constructed a finite element model of the APR1400 reactor internals to identify their modal characteristics. The commercial reactor was selected to reflect the actual boundary conditions. Our FE model was constructed based on scale-similarity analysis and fluid-structure interaction investigations using a fabricated scaled-down model.

Micro Holographic Recording Characteristic With Defocused Micrograting

Cheol-Ki Min,Do-Hyung Kim,Nakyoung Kim,No-Cheol Park,Kyoung-Su Park,Hyunseok Yang,Young-Pil Park IEEE 2011 IEEE transactions on magnetics Vol.47 No.3

<P>The recording of micro holographic storage is performed by the superposition of two tightly focused counter-propagating beams. The micrograting is affected by misalignment in the z -direction during the recording and read-out processes. Thus, the diffraction efficiency (DE) can be reduced by the defocusing of the micrograting. In this paper, we investigate the recording characteristics of a defocused micrograting. An optical system with a numerical aperture (NA) of 0.60 and a wavelength of 532 nm was designed for micro holographic recording. The recording tolerance was formulated by using vector diffraction theory. The recording tolerance was determined by using the Mahajan's Strehl ratio (SR) of the DE. The DE was dramatically reduced at the ±0.4λ defocusing position and we determined that the ±0.4λ was the recording tolerance in the defocusing direction. In addition, we propose a precise detection method to obtain a focus error signal (FES) within the recording tolerance range. Finally, the numerical results of a defocused micrograting were experimentally verified.</P>

Seismic analysis of the APR1400 nuclear reactor system using a verified beam element model

Park, Jong-beom,Park, No-Cheol,Lee, Sang-Jeong,Park, Young-Pil,Choi, Youngin Elsevier 2017 Nuclear engineering and design Vol.313 No.-

<P><B>Abstract</B></P> <P>Structural integrity is the first priority in the design of nuclear reactor internal structures. In particular, nuclear reactor internals should be designed to endure external forces, such as those due to earthquakes. Many researchers have performed finite element analyses to meet these design requirements. Generally, a seismic analysis model should reflect the dynamic characteristics of the target system. However, seismic analysis based on the finite element method requires long computation times as well as huge storage space. In this research, a beam element model was developed and confirmed based on the real dynamic characteristics of an advanced pressurized water nuclear reactor 1400 (APR1400) system. That verification process enhances the accuracy of the finite element analysis using the beam elements, remarkably. Also, the beam element model reduces seismic analysis costs. Therefore, the beam element model was used to perform the seismic analysis. Then, the safety of the APR1400 was assessed based on a seismic analysis of the time history responses of its structures. Thus, efficient, accurate seismic analysis was demonstrated using the proposed beam element model.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A simplified beam element model is constructed based on the real dynamic characteristics of the APR1400. </LI> <LI> Time history analysis is performed to calculate the seismic responses of the structures. </LI> <LI> Large deformations can be observed at the in-phase mode of reactor vessel and core support barrel. </LI> </UL> </P>

Applications of Next Generation Optical Data Storage Technologies

No-Cheol Park,Young-Pil Park,Kyoung-Su Park,Hyunseok Yang IEEE 2011 IEEE transactions on magnetics Vol.47 No.3

<P>In recent years, there have been many research studies focusing on next generation optical data storage technologies, such as near-field recording and holographic data storage systems. Many studies from several disciplines have been perfoed and merged to realize of the next generation optical data storage. The technologies that have been developed for optical data storage are also essential for the other research areas. These technologies can be widely applied to various fields, such as near-field optics-based microscopy, small-sized imaging systems, plasmonic nanolithography using a solid immersion lens (SIL) and a nanoscale aperture, and bio-applications. In this paper, the applications and concepts of the next generation of optical storage technologies are discussed.</P>