• Journal of Electrochemical Science and Technology
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• 제13권1호
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• pp.63-70
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• 2022

Compared with hydrogen, ammonia has the advantages of high gravimetric hydrogen densities (17.8 wt.%), ease of storage and transportation as a chemical hydrogen storage medium, while its application in small-scale on-site hydrogen production scenarios is limited by the need for complex separation equipment during high purity hydrogen production. Therefore, the study of PEMFC, which can directly utilize ammonia decomposition gas, can greatly expand the application of fuel cells. In this paper, the output characteristics, fuel efficiency and the variation trend of hydrogen concentration and local current density in the anode channel of fuel cell with the output voltage of PEMFC fueled by ammonia decomposition gas were studied by experiment and simulation. The results indicate that the maximum output power of the hybrid fuel decreases by 9.6% compared with that of the pure hydrogen fuel at the same inlet hydrogen equivalent. When the molar concentration of hydrogen in the anode channel is less than 0.12, the output characteristics of PEMFC will be seriously affected. Employing ammonia decomposition gas as fuel, the efficiency corresponding to the maximum output power of PEMFC is approximately 47%, which is 10% lower than the maximum efficiency of pure hydrogen.

• 한국응용과학기술학회지
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• 제28권1호
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• pp.85-94
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• 2011

Expanded graphites were used as anode materials of high power Li-ion secondary battery. The expanded graphite was prepared by mixing the graphite with $HClO_4$ as a intercalation agents and $KMnO_4$ as a oxidizing agents. The physical and electrochemical properties of prepared expanded graphites through the variation of process variables such as contents of intercalation agent and oxidizing agent, and heat treatment temperature were analyzed for determination of optimal conditions as the anode of high power Li-ion secondary battery. After examing the electrochemical properties of expanded graphites at the different preparing conditions, the optimal conditions of expanded graphite were selected as 8 wt.% of oxidizing agent, 400 g of intercalation agent for 20 g of natural graphite, and heat treatment at $1000^{\circ}C$. The sample showed the improved charge/discharge characteristics such as 432 mAh/g of initial reversible capacity, 88% of discharge rate capability at 10 C-rate, and 24 mAh/g of charge capacity at 10 C-rate. However, the expanded graphite had the problems of potential plateaus like natural graphite and lower initial efficiency than the natural graphite.

• 대한환경공학회지
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• 제39권8호
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• pp.489-493
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• 2017

미생물연료전지는 하폐수에 존재하는 다양한 유기성물질을 전기에너지로 변환시킬 수 있는 생물전기화학적공정이다. 본 연구에서는 전산모사를 통하여 산화전극의 크기, 전극간 거리, 전체 산화전극면적이 기질분해에 미치는 영향을 알아보고자 하였다. 생활하수를 처리하는 다중산화전극 및 SPA (Spaced electrode assembly)형 연속식 미생물연료전지공정을 모사하였으며, 전산모사결과에 따르면 단일전극의 크기에 의한 영향보다는 전극간 거리가 짧을수록 기질분해속도가 빠른 것으로 나타났다. 특히 전체 산화전극의 면적이 큰 경우가 기질분해가 가장 빠른 것으로 나타났다. 본 연구를 통하여 미생물연료전지공정의 설계에 있어서 율속단계로 알려진 환원전극의 크기 외에도 산화전극의 크기 및 전극간 거리 또한 기질분해 속도에 영향을 미칠 수 있는 중요한 인자임을 알 수 있었다.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2396-2400
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• 2007

Transparent In-doped (1 at.%) zinc oxide (IZO) thin films are deposited by pulsed DC magnetron sputtering with H2 mixed Ar atmosphere on glass substrate without any heating process. Even at room temperature, highly c-axis oriented IZO thin films were grown in perpendicular to the substrate. The hydrogenated IZO (IZO:H) film isolated in H2 atmosphere for 30 min exhibited an average optical transmittance higher than 85% and low electrical resistivity of less than 2.7 × 10?3 Ω·cm. These values are comparable with those of commercially available ITO. Each of the IZO films was used as an anode contact to fabricate organic light-emitting diodes (OLEDs) and the device performances studied. At the current density of 1 × 103 A/m2, the OLEDs with IZO:H (H2) anode show excellent efficiency (11 V drive voltage) and a good brightness (8000 cd/m2) of the light emitted from the devices, which are as good as the control device built on a commercial ITO anode.

• 전기화학회지
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• 제11권4호
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• pp.262-267
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• 2008

직접개미산 연료전지의 전극 촉매로 사용되는 귀금속 백금-루테늄 촉매를 정전분무법을 이용하여 효율적으로 분산하여 보았다. 전극에 도포된 촉매 양은 분사 시간에 따라 증가하였으나, 분사시간이 80분을 넘는 경우 촉매 응집으로 인하여 연료전지 성능은 감소하는 경향을 보였다. 상용 핸드스프레이로 전극 촉매를 $3.0\;mg/cm^2$ 분산한 경우 얻은 최대 출력밀도 $74\;mW/cm^2$와 비교하여 정전분무법은 적은 양인 $1.85\;mg/cm^2$의 촉매를 분산하고도 $72\;mW/cm^2$의 최대 출력밀도를 얻을 수 있었다.

• 상하수도학회지
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• 제25권4호
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• pp.591-596
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• 2011

Surface floating air cathode microbial fuel cell (MFC) having horizontal flow was developed for the application of MFC technology. RVC (Reticulated vitreous carbon) coated with anyline was used as anode electrode and carbon cloth coated with Pt (5.0 g Pt/$m^2$, GDE LT250EW, E-TEK) was used as cathode electrode. As results of continuous operation with changing the flow rate from 4.3 mL/min to 9.5 mL/min, maximum power density of 4.5 W/$m^3$ was acquired at 5.4 mL/min, which was at 0.35 m/hr of flow velocity under anode electrode. When the ratio of cathode surface area to anode surface area($A_c/A_a$) was changed to 1.0, 0.5, and 0.25, the maximum power density of 2.7 W/$m^3$ was shown at the ratio of 1.0. As the ratio decreased from 1.0 to 0.25, the power density also decreased, which is caused by increasing the internal resistance resulted from reducing the surface area to contact with oxygen. Actually, internal resistances of the ratio of 1.0, 0.5, and 0.25 were 63.75${\Omega}$, 142.18${\Omega}$, and 206.12${\Omega}$, respectively.

• 한국진공학회지
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• 제17권3호
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• pp.247-252
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• 2008

휴대용 XRF(X-Ray Fluorescence) 장치에 적용하기 위하여 개발한 투과 양극형 x-ray tube를 이용하여 XRF 실험을 하고, x-ray tube가 XRF data에 미치는 영향을 조사하였다. W-target tube와 Rh-target tube를 이용하여 측정한 XRF data는 알려진 결과와 잘 일치하였다. 35 kV와 관전압과 $40{\mu}A$의 관전류에서 W-target tube로 측정한 Fe $K_{\alpha}$-line의 FWHM은 약 180 eV로써, 이 값은 물질의 성분분석을 하기에 충분한 것으로 확인하였다. XRF data와 x-ray tube의 적분강도 곡선을 비교 분석해 본 결과, 휴대용 XRF 장치에는 W-Target tube보다는 Rh-Target tube를 사용하는 것이 더 유리함을 밝혀내었다.

• 공업화학
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• 제35권1호
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• pp.37-41
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• 2024

열대성 과일로 널리 재배되고 있는 코코넛(coconut)의 독특한 껍질(shell)은 과육 섭취 후 얻어지는 부산물로 활용 가치가 클 것으로 기대된다. 이 코코넛 껍질을 전도성 고분자와 혼합하여 복합소재를 간단한 방식으로 제조하고 섭씨 600도 정도의 상대적 저온에서 탄화하여 수득되는 소재의 전기화학적 특성 및 활용 가능성을 고찰하였다. 먼저, 외형적 요소를 주사전자현미경(scanning electron microscope, SEM)으로 관찰하였다. 탄소의 미세구조를 라만(Raman) 분광 분석을 통하여 추론하였다. 전기전도 가능성을 간단한 옴의 관계(Ohmic relation)를 통하여 확인하였다. 나아가, 탄화된 재료가 리튬 이차 전지의 음극(anode) 소재로 활용될 수 있는지 여부를 반쪽 전지(half-cell) 충방전(charge/discharge) 테스트를 통해 살펴보았으며, 최대 충전 용량은 약 750 mAh로 높게 나타났으나, 충전이 진행됨에 따라 빠른 감소를 보였다. 본 연구는 향후 목질계 폐기물의 활용에 대한 중요한 정보를 제공할 것이다.

• 치과방사선
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• 제3권1호
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• pp.19-28
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• 1973

The author has studied maxillo-facial anatomical landmarks using Status X with two methods. The one has performed by application of contrast media on the human dry skull, the other has performed on living human skull as control group. Comparing the panagraphs taken by two methods, the author has drawn following results: 1. The panagraphs revealed the undistorted, highly sharp panoramic shadows of each jaw on a film. 2. Diminishing the inserted anode tube overlapping-free representation of the anterior teeth was taken. 3. Alternating the head position of the objects, direction of anode tube and film placing, the shadows of temporo-mandibular joint and zygomatic arch were taken without overlapping the other bone tissues. 4. In the panagraphs applied various shaped contrast media to each anatomical landmark, a radio-anatomical atlas which is necessary to interpret various bone tissues was taken. 5. In order to interpret panagraphic shadows easily, the author has tried this study by comparing the films of the living human skull with the films of the human dry skull applied contrast media.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.31-34
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• 2004

Feasibility of electrokinetic(EK)-Fenton process and Ozone chemical oxidation were investigated for tile removal of organic contaminants and heavy metals from the contaminated soil. In EK-Fenton process, accumulated electroosmotic flow(EOF) was 80 L for 26 days. Removal efficiency of TPH, As, and Ni were 61%, 36%, and 47%, respectively. The concentration of As was high near the anode due to the transport of anionic As toward the anode, while the concentration of Ni was high near the cathode by the movement of cationic Ni to the cathode. Field scale application of in-situ ozonation was carried out for removal of TPH in 3-D test cell (3 m$\times$2 m$\times$2 m). After 25 days of ozone injection, more than 80% of removal rate was observed through the test cell.