열전지용 황철석(FeS₂) 입자크기 변화에 따른 전기화학반응 메커니즘

박병준,Park, Byeong June 한국전기전자재료학회 2017 전기전자재료학회논문지 Vol.30 No.4

Pulverized $FeS_2$ (pyrite) gives different discharge test results with as-received $FeS_2$ electrodes. The as-received $FeS_2$ electrode shows three voltage plateaus during the discharge test. However, the ball-milled $FeS_2$ electrode shows two voltage plateaus. To interpret this result, the effect of $FeS_2$ particle size on electrochemical reactions is investigated by unit cell discharge tests, SEM and XRD. As a result, it is found that the transition reaction product ($Li_2+xFe+xS_2$) of $FeS_2$ explains the difference. The as-received $FeS_2$ reacts according to three reaction steps ($FeS_2{\rightarrow}Li_3Fe_2S_4{\rightarrow}Li_2+xFe_1+xS_2{\rightarrow}LiFe_2S_4$). However, ball-milled $FeS_2$ reacts without the $Li_2+xFe_1+xS_2$ stage. In this study, this result is explained by the difference in electrochemical reaction mechanism. The as-received $FeS_2$ has a larger radius than the ball-milled $FeS_2$. Therefore, the lithium ion has to diffuse into the $FeS_2$ unreacted core, and $Li_2+xFe_1+xS_2$, the transition reaction product of as-received $FeS_2$, is formed during this stage.

당뇨환자에서 당뇨망막병증과 베바시주맙 안내주입술이 맥락막 두께에 미치는 영향

박병준,정혜원,김형찬.Byeong Jun Park. MD. Hye Won Chung. MD. PhD. Hyung Chan Kim. MD. PhD 대한안과학회 2013 대한안과학회지 Vol.54 No.10

Purpose: To evaluate the effect of diabetic retinopathy on choroidal thickness and the changes of choroidal thickness after intravitreal bevacizumab injection (IVB) in diabetic patients. Methods: The present study included 105 patients (105 eyes). Patients were classified into 6 groups: control group (A); no change (B), mild (C), moderate (D), and severe (E) non proliferative diabetic retinopathy (NPDR); and proliferative diabetic retinopathy (PDR) (F), with 15 diabetic patients in each group. All patients underwent enhanced depth imaging spectraldomain optical coherence tomography (EDI OCT) to evaluate choroidal thickness. An additional 15 patients (15 eyes) with diabetic retinopathy treated with IVB were also included. These patients underwent EDI OCT before and 1 month after IVB. Results: Mean choroidal thickness was significantly thinner in the moderate and severe NPDR, and PDR groups compared with the control group. Moreover, when comparing sequential stages of diabetic retinopathy progression, the choroidal thickness in the moderate NPDR stage and PDR stage was found to be significantly thinner than in the mild and severe NPDR, respectively. Additionally, choroidal thickness was 187.3 μm before IVB and significantly decreased to 168.9 μm 1 month after IVB (p < 0.05). Conclusions: Choroidal thickness is related to the severity of diabetic retinopathy and is significantly decreased after IVB. J Korean Ophthalmol Soc 2013;54(10):1520-1525

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.

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.

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.

킬라우에아 현무암의 미량원소에 대한 지구화학적 연구

박병준,장윤득,권석범,김정진,Park, Byeong-Jun,Jang, Yun-Deuk,Kwon, Suk-Bom,Kim, Jeong-Jin 대한자원환경지질학회 2007 자원환경지질 Vol.40 No.5

킬라우에아 화산 정상 분화구는 16세기 이래로 계속적이고도 간헐적인 분출활동을 통하여 형성되어진 화산으로서 1790년부터 1982년 9월까지 분출된 현무암의 체계적인 연도별 시료채취를 바탕으로 미량원소와 희토류원소의 특징을 고찰하였다. 주요 정출광물로는 감람석, 단사휘석, 사장석이 있으며 소량의 불투명광물인 크롬스피넬, 티탄철석이 관찰된다. Zr, V, Y, Ti 등과 같은 미량원소들은 MgO로 나타나는 감람석에 대해서 불호정성을 나타내며 Ni, Cr, Co 는 감람석에 대해서 매우 강한 호정성을 나타낸다. Ba, Rb, Th, Sr, Nd 원소들은 불호정성을 나타내어 $K_2O$와 정(+)의 관계를 뚜렷이 나타낸다. 희토류원소를 콘드라이트에 표준화시킨 REE도표에서 LREE가 HREE보다 더 부화된 패턴을 보이는 전형적인 화산호현무암(OIB)을 지시한다. Si에서 약간의 변곡 현상으로부터 소량의 사장석 분별결정작용에 Sr이 관여한 것을 확인할 수 있었다. Y/Ho, Zr/Hf 비로부터 마그마로 유입되는 외부적인 유체(해수 혹은 지하수)의 영향을 고려해 보았을 때 유체의 영향은 거의 나타나지 않았으며 Zr/Hf에서 푸오오(PuuOo)분출암과 킬라우에아(Kilauea)정상 분화구 분출 현무암과의 뚜렷한 차이를 발견하였다. 분출 시대별 미량원소의 함량변화를 관찰하였으며 특히 1921년에서 1954년 사이 동안에 마그마 성분의 급작스런 변화에 의해 그 이전의 대체로 증가하던 미량원소의 함량이 감소하는 경향으로 바뀌게 되었다. 이러한 경향은 킬라우에아 정상 분화구의 분출이 끝나고 계속된 푸오오 분출 현무암의 미량원소의 거동 또한 감소하는 경향을 따르고 있다. 1924년 할레마우마우 분화구가 함락 붕괴되어 지각성분의 마그마 저장소로의 유입과 마그마 저장소 아래에서 공급되는 모마그마의 성분변화에 의해서 미량원소 함량이 급격하게 변한 것으로 해석된다. Kilauea volcano's summit area was formed by continuous ind/or sporadic eruption activities for several hundreds years. In this study, we mainly focused on the trace elements characteristics through systematic sample rocks erupted from 1790 to September of 1982. Under the microscope it can be observed some main minerals such as olivine, clinopyroxene. and plagioclase with minor opaque minerals including Cr-spinel and ilmenite. Zr, V, Y, Ti elements show incompatible activities with MgO while Ni, Cr, Co elements show highly compatible properties. Elements like as Ba, Rb, Th, Sr, Nd are highly incompatible to show positive trends with $K_2O$. In the REE diagram LREE is more enriched than HREE suggesting typical Oceanic Island Basalt(OIB) type. It can be suggested that Sr have an effect on the fractionation of plagioclase from the kink in the $K_2O$ variation diagram. Y/Ho ratio diagram shows there was no fluids effect in the historical Kilauea volcano but Zr/Hf ratio diagram shows a significant difference between Kilauea lavas and PuuOo lavas. There are distinctive changes of trace element contents showing in particular abrupt changes of temporal variations between 1924 and 1954. Moreover, PuuOo lavas which had been erupted since 1983 follow these decreasing trends of trace element variation. Therefore, it is strongly suggested that these abrupt changes of trace elements trends result from the huge collapse geological event which formed Halemaumau crater in 1924 causing contamination effects of crustal contents into magma chamber and from the changes of parental magma composition injected into Kilauea volcano's summit magma reservoir.

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.

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.

오픈소스 CFD 코드 $OpenFOAM^{(R)}$에 대한 소개와 사용법 상(上)

박병준,Park, Byeong-Jun 한국수자원학회 2011 물과 미래(한국수자원학회지) Vol.44 No.11

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.