10 kWh급 초전도 베어링 회전자의 기계적 특성 평가

박병준,정세용,김철희,한상철,박병철,한상진,두승규,한영희,Park, B.J.,Jung, S.Y.,Kim, C.H.,Han, S.C.,Park, B.C.,Han, S.J.,Doo, S.G.,Han, Y.H. 한국초전도학회 2011 Progress in superconductivity Vol.13 No.1

Recently, superconductor flywheel energy storage systems (SFESs) have been developed for application to a regenerative power of train, a power quality improvement, the storage of distributed power sources such as solar and wind power, and a load leveling. As the high temperature superconductor (HTS) bearings offer dynamic stability without the use of active control, accurate analysis of the HTS bearing is very important for application to SFESs. Mechanical property of a HTS bearing is the main index for evaluating the capacity of an HTS bearing and is determined by the interaction between the HTS bulks and the permanent magnet (PM) rotor. HTS bearing rotor consists of PM and iron collector and the proper dimension design of them is very important to determine a supporting characteristics. In this study, we have optimized a rotor magnet array, which depends on the limited bulk size and performed various dimension layouts for thickness of the pole pitch and iron collector. HTS bearing rotor was installed into a single axis universal test machine for a stiffness test. A hydraulic pump was used to control the amplitude and frequency of the rotor vibration. As a result, the stiffness result showed a large difference more than 30 % according to the thickness of permanent magnet and iron collector. This is closely related to the bulk stiffness controlled by flux pining area, which is limited by the total bulk dimension. Finally, the optimized HTS bearing rotor was installed into a flywheel system for a dynamic stability test. We discussed the dynamic properties of the superconductor bearing rotor and these results can be used for the optimal design of HTS bearings of the 10kWh SFESs.

심장이식 수혜자의 사회적지지, 우울 및 건강상태

박병준,신나미,Park, Byung-Jun,Shin, Nah-Mee 한국중환자간호학회 2014 중환자간호학회지 Vol.7 No.1

Purpose: As the number of cases of heart transplantation (HT) and the survival rate have increased, concerns regarding post-HT life have grown. This study was conducted to explore the relationships of perceived social support to the depression and health status of HT recipients. Methods: This descriptive study targeted all recipients who had undergone HT at S University Hospital since 1994, and 32 recipients were recruited. Results: 90.6% of the recipients were men, and the average age at the time of surgery was $47.4{\pm}13.4$ years. The ejection fraction was increased from $18.47{\pm}5.63%$ to $63.25{\pm}7.57%$, and 31 cases of New York Heart Association (NYHA) class III and IV improved to class I or II after HT. The patients reported mild depression even with high perceived social support and improved health status after HT. Among those resource persons who offered support, they reported their spouse, doctors, and nurses as most meaningful to them. Conclusion: This study confirmed the positive effects of HT on the recipients' physical improvement. It also added the discovery that the importance of recipients' subjective perception of social support might be critical for their more successful recovery and adjustment to post-HT life. Focusing on a different approach to social support and types of social resources in the recovery phase is suggested for future studies on quality of life after HT.

고전압 대전류 송전에 적합한 절연관 부스바 소개

박병준,Park, Byeong-Jun 한국열병합발전협회 2011 열병합발전 Vol.80 No.-

고전압, 대전류의 송전을 위한 기존의 케이블 포설법과 부스덕트 시공법상 발생하기 쉬운 여러 문제점에 대한 보완 개선되어 새롭게 개발된 HiViPS (High Voltage/Current Insulation Pipe Bus-bar System)라는 복합 차폐 절연관 부스바(Complex Insulation Pipe Tubular Bus-bar)를 소개한다.

에너지 저장장치용 슈퍼커패시터 이온 도핑 제어를 통한 에너지 밀도 향상 연구

박병준,유선미,양성은,한상철,노태무,이영희,한영희,Park, Byung-jun,Yoo, SeonMi,Yang, SeongEun,Han, SangChul,No, TaeMoo,Lee, Young Hee,Han, YoungHee 한국전력공사 2019 KEPCO Journal on electric power and energy Vol.5 No.3

최근 전력 계통에 사용되는 주파수 조정용(F/R) 에너지 저장장치에 대하여 높은 에너지 밀도와 장수명의 안정성에 대한 요구가 증대되고 있다. 이와 관련하여 슈퍼커패시터는 장수명과 급속 충방전 특성이 우수하므로 이러한 F/R 적용을 위한 에너지 저장장치로 적합하게 여겨지고 있다. 슈퍼커패시터는 단주기 F/R 영역의 보완 운전을 담당하고 전력계통에 설치된 ESS의 장주기 운영 수명을 연장함으로써 기존 용량을 담당하는 리튬 배터리의 설치 규모와 양을 획기적으로 줄일 수 있다. 하지만 낮은 에너지 밀도는 전력 계통과 같은 큰 시스템에서 적용에 한계가 있으며 여전히 배터리를 대체할 수 있는 높은 에너지 밀도 요구에 어려움을 겪고 있다. 그러나 최근에는 리튬이온 커패시터(Lithium ion capacitor; LIC) 구조가 3.8 V 이상의 전압 구간을 구현할 수 있기 때문에 전기이중층 커패시터(Electric double layer capacitor; EDLC) 구조보다 고에너지 밀도 구현을 위한 구조로 각광을 받고 있지만 여전히 상용화를 위해서는 여러가지 전기화학적 성능에 대한 구체적인 검증 및 개발이 필요한 실정이다. 본 연구에서는 LIC의 에너지 밀도와 관계되는 용량을 증대하기 위하여 새로운 전극사전-도핑 방법을 설계하였다. 양극 활물질은 0.1% 이하의 상대습도 분위기 드라이룸에서 기계적 강도와 음극 도핑을 안정되게 수행될 수 있도록 $100{\mu}m$의 두께로 제작되었다. 또한 접촉 저항을 최소화하기 위하여 제조된 전극은 상온에서 $65^{\circ}C$까지 열 압축공정을 실시하였다. 최종적으로 LIC 구조에 대한 다양한 사전-도핑법을 설계하고 그 메커니즘을 분석하여 용량과 전기화학적 안정성이 향상된 새로운 LIC 사전-도핑 방법을 제안하였다. Recently, demand for high energy density and long cycling stability of energy storage system has increased for application using with frequency regulation (F/R) in power grid. Supercapacitor have long lifetime and high charge and discharge rate, it is very adaptable to apply a frequency regulation in power grid. Supercapacitor can complement batteries to reduce the size and installation of batteries. Because their utilization in a system can potentially eliminate the need for short-term frequent replacement as required by batteries, hence, saving the resources invested in the upkeep of the whole system or extension of lifecycle of batteries in the long run of power grid. However, low energy density in supercapacitor is critical weakness to utilization for huge energy storage system of power grid. So, it is still far from being able to replace batteries and struggle in meeting the demand for a high energy density. But, today, LIC (Lithium Ion Capacitor) considered as an attractive structure to improve energy density much more than EDLC (Electric double layer capacitor) because LIC has high voltage range up to 3.8 V. But, many aspects of the electrochemical performance of LIC still need to be examined closely in order to apply for commercial use. In this study, in order to improve the capacitance of LIC related with energy density, we designed new method of pre-doping in anode electrode. The electrode in cathode were fabricated in dry room which has a relative humidity under 0.1% and constant electrode thickness over $100{\mu}m$ was manufactured for stable mechanical strength and anode doping. To minimize of contact resistance, fabricated electrode was conducted hot compression process from room temperature to $65^{\circ}C$. We designed various pre-doping method for LIC structure and analyzing the doping mechanism issues. Finally, we suggest new pre-doping method to improve the capacitance and electrochemical stability for LIC.

외상성 저안압황반병증 환자에서 유리체강내 공기주입술로 치료한 1예

박병준,신현진,김형찬,Byeong Jun Park,Hyun Jin Shin,Hyung Chan Kim 대한안과학회 2013 대한안과학회지 Vol.54 No.12

Purpose: To report a case of traumatic hypotony maculopathy treated by intravitreal air injection.<br /> Case summary: A 20-year-old female presented with decreased visual acuity in the left eye 2 days after trauma. Best corrected visual acuity (BCVA) was 0.5 and the intraocular pressure (IOP) was 5 mm Hg. Indirect ophthalmoscopy revealed chorioretinal folds in the macular area. Gonioscopy showed angle recession from 4 to 7 o’clock. Initially, pressure patching and conservative management were performed on the left eye 10 days after examination. However, deterioration of the chorioretinal fold was observed without any change in IOP. Finally, intravitreal air injection (0.5 cc) was performed 10 days after the start of conservative treatments. Following air injection, the normalization of IOP and gradual reduction of chorioretinal fold was observed. BCVA improved to 1.0 and IOP was maintained between 12 and 14 mm Hg for 24 months after the air injection.<br /> Conclusions: Intravitreal air injection may safely and effectively treat traumatic hypotony maculopathy.<br /> J Korean Ophthalmol Soc 2013;54(12):1935-1938

4D Lookup Table Interpolating을 이용한 단위 전지 방전 시험 기반 열전지 성능 예측

박병준,김지연,하상현,조장현,Park, Byeong June,Kim, Ji Youn,Ha, Sang Hyeon,Cho, Jang Hyeon 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.6

For comparison to the Li-ion battery, evaluating a thermal battery must consider additional variables. The first one is the temperature difference between the battery and its unit cell. Thermal batteries and their unit cells have a temperature difference that is caused by the thermal battery activation mechanism and its shape. The second variable is the electrochemical reaction steps. Most Li-ion batteries have a constant electrochemical reaction at the electrode, and battery voltage is affected when the concentration of Li ions is changed. However, a thermal battery has several steps in its electrochemical reaction, and each step has a different potential. In this study, we used unit cell discharge tests based on interpolating a 4D lookup table to estimate the performance of a thermal battery. From the test results, we derived an estimation algorithm by interpolating the table, which is queried from specified profile groups. As a result, we found less than a 5 percent difference between estimation and experiment at the 1.3 V cut-off time.

디지털 PCR을 응용한 특정 amoA유전자를 가진 질산화 Archaea 동정

박병준,박수제,이성근,Park, Byoung-Jun,Park, Soo-Je,Rhee, Sung-Keun 한국미생물학회 2007 미생물학회지 Vol.43 No.3

Mesophilic Crenarchaeota have been known to be predominant among ammonia-oxidizing microorganisms in terrestrial and marine environments. In this study, we determined the archaeal phylotypes carrying specific amoA by combining digital PCR and multiplex-nested PCR. Analysis of samples in which amoA and 16S rRNA gene were amplified showed that amoA gene diversity was relatively higher than that of 16S rRNA gene. Nitrifying archaeal group I.1a was dominant over I.1b group of crenarchaota and euryarchaeota. This approach could be applied for interrelating a functional gene to a specific phylotype in natural environments. 해양 및 토양에서의 암모니아 산화는 세균에 비해 Crenarchaeota 그룹의 archaea에 의해 우세하게 일어나고 있음이 알려졌다. 서해 갯벌에서, 배양에 의존하지 알고, 특정 암모니아 산화유전자(amoA)를 가진 archaea을 동정하고자 디지털 PCR법을 응용한 nested PCR법을 개발하였다. amoA와 16S rRNA유전자가 동시에 증폭된 샘플의 분석결과, 16S rRNA유전자에 비해 amoA 유전자의 다양성 이 높았으며, I.1a 그룹의 crenarchaea가 I.1b 그룹의 crenarchaea보다 갯벌지역에서 암모니아 산화에 우점적으로 기여하고 있음을 알 수 있었다. 본 연구에서 시도된, 디지털 PCR과 multiplex-nested PCR을 접목한 접근법을 이용하면 특정 기능유전자를 가진 미생물을 환경에서 검증하는데 응용할 수 있을 것이다.

10 kWh급 초전도 플라이휠 베어링의 강성 평가

박병준,정세용,이정필,박병철,김철희,한상철,두승규,성태현,한영희,Park, B.J.,Jung, S.Y.,Lee, J.P.,Park, B.C.,Kim, C.H.,Han, S.C.,Du, S.G.,Sung, T.H.,Han, Y.H. 한국초전도학회 2009 Progress in superconductivity Vol.11 No.1

A superconductor flywheel energy storage(SFES) system is mainly act an electro-mechanical battery which transfers mechanical energy into electrical form and vice versa. SFES system consists of a pair of non-contacting High Temperature Superconductor (HTS) bearings with a very low frictional loss. But it is essential to design an efficient HTS bearing considering with rotor dynamic properties through correct calculation of stiffness in order to support a huge composite flywheel rotor with high energy storage density. Static properties of HTS bearings provide data to solve problems which may occur easily in a running system. Since stiffness to counter vibration is the main parameter in designing an HTS bearing system, we investigate HTS bearing magnetic force through static properties between the Permanent Magnet(PM) and HTS. We measured axial / radial stiffness and found bearing stiffness can be easily changed by activated vibration direction between PM and HTS bulk. These results are used to determine the optimal design for a 10 kWh SFES.

순환상관(Cyclic Correlation)을 이용한 OFDM 시스템에서의 블라인드 동기 알고리즘

박병준,고은석,강창언,홍대식,Park Byungjoon,Ko Eunseok,Kang Changeon,Hong Daesik 한국통신학회 2005 韓國通信學會論文誌 Vol.30 No.1C

본 논문에서는 OFDM 시스템의 시간 오차와 주파수 오차를 추정하는 방안을 제시하고 있다. 제안한 동기 알고리즘은 수신 신호의 순환상괸(cyclic correlation)을 이용하며, 이 순환상관에는 시간과 주파수 오차 정보가 모두 나타나게 된다. 따라서 제안하는 추정 알고리즘은 여분의 학습심볼(training symbol)를 필요로 하지 않으며, 채널의 정보를 사용하지 않는다. 제안한 추정 방법은 평균자승오차(mean square error) 성능에서 잡음이나 채널의 특성에 상관없이 거의 일정한 성능을 가지며, 실험 결과는 이러한 특징을 뒷받침 해주고 있다. 좀 더 정확한 추정을 위해서, 순환 상관을 평균을 취하는 방법이 적용되었다. 이 경우, 평균을 취하는 방법은 평균을 취하지 않는 방법보다 훨씬 더 정확한 추정을 가능하게 한다. In this paper, blind synchronization algorithm is developed for estimating jointly timing and frequency offset of OFDM system. The proposed estimator exploits the second-order cyclostationarity of received signals, and then uses the information of symbol timing and carrier frequency offset appeared in the cyclic correlation. As a bling estimator, the information of impulse response of channel and training symbols are not required. The performance of the proposed method is consistent in spite of channel conditions in mean squre error sense, and simulation results prove it. For more accurate estimaion, the method that averages cyclic correlation is applied. In this case, the performance of averaging method is better.

준설토 배송관로 내에서의 개질재 혼합효율에 대한 CFD 해석

박병준,강병윤,정민철,신재렬,Park, Byongjun,Kang, Byungyoon,Chung, Minchul,Shin, Jaeryul 대한토목학회 2015 대한토목학회논문집 Vol.35 No.5

본 연구는 준설매립과정에서의 관중혼합 거동을 3차원 전산유체역학(CFD, Computational Fluid Dynamics)을 통해 분석한 연구로 준설토 배송관과 개질재 주입관이 합류하며 발생되는 이상(2-phase)유체의 혼합효율을 사전 평가함으로써 관중혼합 양상을 고찰하는 물리실험의 시행착오를 줄여 경제성을 증진시키는데 연구목적을 두고 있다. 수치해석에 이용된 CFD 코드는 OpenFOAM$^{(R)}$이고, 몇 가지의 기본가정 하에 배송관-주입관의 관경과 합류각을 변화시켜 총 18가지 경우에 대한 삼상(3-phase)유체 거동을 모의하였다. 그 결과 혼합효율에 대한 우열은 있었으나 그 차이는 미미하였고, 모든 경우에서 각 재료 사이의 경계층이 뚜렷하게 형성되었다. 이러한 현상을 극복하기 위한 보완 실험을 통해 경계층 파쇄(破碎)를 위한 관 내 부속 구조물이 고안되었으며, 본 연구에서 제시된 구조물은 단거리 배송관로 내 준설토와 개질재의 혼합효율을 크게 향상시킬 수 있음을 확인할 수 있었다. This study utilised Computational Fluid Dynamics(CFD) for preliminary assessment of mixing efficiencies of 2-phase fluids in a pipe at which a slurry flow and an injected solidifier join, for the purposes of reducing trial-and-error-based instances of physical experiments and conducting the overall research in an economical way. Using OpenFOAM$^{(R)}$, we simulated behavior of 3-phase fluids under 18 different settings generated by changing diameters of a dredged soil transportation pipe, a quality improving material injection pipe and the confluence angle. While difference in mixing efficiencies amongst the instances was insignificant, discernible boundary layers amongst the materials were observed in all of the instances. In order to break the boundary layers, we designed a substructure inside a pipe and found out that it could remarkably improve mixing efficiencies particularly for short distance applications.