• Title/Summary/Keyword: 기공소

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Scientific Investigation of the Clothes Collected at Comfort Station in Nara, Japan (일본 나라현 위안소 수습 의복 조사 및 과학적 분석)

  • Choi, Jung Eun;Jeon, Yu Ree;Lee, Yu Jin;Kim, Min Seo;Jin, Chul Min
    • Journal of Conservation Science
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    • v.33 no.5
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    • pp.363-370
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    • 2017
  • The aim of this study was to obtain information about two early-20th Century clothes, for which the "National Memorial Museum of Forced Mobilization under Japanese Occupation" has sought to receive preservation treatment. Optical microscopes and a scanning electron microscope were used to investigate the weaving of the clothes, and Fourier transform infrared spectroscopy(FT-IR) was used to investigate the fibers. Cloth A is believed to be a Japanese half sleeved inner wear(Hanjuban) used by women. Cloth B is believed to be working clothing that was checked by an Osaka plant. This was verified by a book written by the Japanese army. Both of the clothes were made mostly from cotton, although the inner wear also used viscose rayon on the neck collar. The button on the working wear was made of urea formaldehyde resin, an early precursor to plastic.

Evaluation of Fracture Strength of WA-Vitrified and Resinoid Bond Grinding Wheels by Acoustic Emission (AE에 의한 WA계 비트리파이드 및 레지노이드 結合劑硏削숫돌의 破壞强度評價)

  • 강명순;한응교;권동호
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.12 no.2
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    • pp.241-251
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    • 1988
  • The purpose of this paper is to evaluate fracture strength of WA-vitrified and resinoid bond grinding wheels by means of acoustic emission. The paper conducts tension test, compression test, splitting tensile test and bending test with AE measuring system. These tests have been carried out in accordance with the grain sizes and grades of grinding wheels. The fracture strength of grinding wheels is evaluated by the clarification of biaxal fracture criterion of Babel and Sines. It clarifies the influence of factors of grinding wheel upon AE characteristics and evaluates the predictability of life of grinding wheels and the perception of fracture.

Adsorption of VOCs from Dry Cleaning (세탁소 배출 휘발성유기화합물의 흡착 제거 기술)

  • Lee, Seung-Jae;Moon, Seung-Hyun
    • Journal of Korean Society of Environmental Engineers
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    • v.31 no.11
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    • pp.1025-1032
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    • 2009
  • This study investigated a possibility to develop an adsorption process for volatile organic compounds (VOCs) of the solvent emitted during dry cleaning. Pitch activated carbon fiber (ACF) was chosen as an adsorbent of VOCs, and an electric swing adsorption process was utilized for the reproduction of the adsorbent after the completion of VOCs adsorption. Effects of ACF types and several solvents such as trichloroethylene (TCE) and toluene were examined on breakthrough curves and amounts of adsorbed VOCs. ACF was pretreated under various conditions in order to enhance the amounts of the adsorbed VOCs. Temperatures and voltages were measured for the reproduction of the ACF after full adsorption. ACF having micropores exhibited high adsorption of TCE, and high surface area of ACF could increase the adsorption property of toluene. In general, ACF could adsorb 41~54% TCE of the adsorbent weight. The increase of inlet VOCs concentration significantly decreased the breakthrough time and slightly lowered the amounts of adsorbed VOCs. Thus, ACF could effectively adsorb VOCs in low concentration in the feed stream. ACF pretreated by heat under vacuum showed excellent toluene adsorption with controlling oxygen functional groups on the ACF surface, which revealed that vacant carbon site could be the adsorption point of toluene. Most adsorbed toluene was desorbed at $150^{\circ}C$.

REMOVABLE FLEXIBLE DENTURE FOR CHILDREN WITH OLIGODONTIA : A CASE REPORT (탄성의치를 사용한 부분무치증 환아의 보철적 수복)

  • Kim, Jin-Young;Lee, Kwang-Hee;La, Ji-Young;Lee, Dong-Jin;An, So-Youn;Kim, Yun-Hee
    • Journal of the korean academy of Pediatric Dentistry
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    • v.36 no.1
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    • pp.150-156
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    • 2009
  • Objectives : The conventional removable appliance, composed of wires and acrylic resin, had unaesthetic results and poor retention. The flexible denture, as an alternative, presents improved aesthetics with the thin and strong resin retentive area. In addition, it also enhances patients' sensory function as a result of decreased volume of denture base. The flexibility of the flexible denture reduces the possibility of fracture and distributes the masticatory forces transmitted to the abutments and residual bone tissue. This report describes a 10-year-old girl and a 6-year-old boy with oligodontia treated with the flexible dentures as an alternative to conventional removable appliances. Methods : Impression was taken using alginate material and sent to a laboratory with the bite for fabrication of the flexible denture. Prior to try-in, the flexible denture was immersed in water at $90^{\circ}C$ for one minute and cooled. Impinging area of the denture was checked by $Fit-Checker^{(R)}$ and removed and the denture was delivered to the patient. Results : Both patients were satisfied with the flexible dentures, which presented improved retention and aesthetics. Conclusion : For patients with oligodontia, flexible dentures can be considered as a treatment of choice, which may replace the conventional denture.

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Effect of $N_2$-back-flushing Time and TMP in Lake Water Treatment Using Multichannel Ceramic Microfiltration Membranes (다채널 세라믹 정밀여과막으로 호소수 처리시 질소 역세척 시간 및 막간 압력차의 영향)

  • Park, Jin-Yong;Park, Bo-Reum
    • Membrane Journal
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    • v.17 no.2
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    • pp.124-133
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    • 2007
  • In this study, we treated lake water by 2 kinds of multichannel ceramic micro filtration membranes. We could investigate effects of $N_2-back-flushing$ time (BT) and transmembrane pressure (TMP), and find optimal operating conditions. The BT were changed in $10{\sim}60$ sec, TMP in $0.6{\sim}2.0$ bar at fixed filtration time (FT) 8 min, flow rate 2.0 L/min and back-flushing pressure 2.0 bar. Also, the optimal conditions were discussed in the viewpoints of resistance of membrane fouling $(R_f)$, dimensionless permeate flux $(J/J_o)$, permeate flux (J) and total permeate volume $(V_T)$. As result, optimal back-flushing conditions for HC04 ($0.4{\mu}m$ pore size) and HC10 membrane $(1.0{\mu}m)$ were BT=10 sec and BT=20 sec, respectively. Then, higher TMP should increase the driving force, and could produce more VT. Average rejection rates of pollutants were higher than 95.4% for turbidity, $12.7{\sim}20.1%\;for\;COD_{Mn},\;0.0{\sim}6.4%\;for\;NH_3-N,\;1.9{\sim}4.6%$ for T-N and $34.9{\sim}88.4%$ for T-P.

재료 동적영향을 고려한 주냉각재 배관 LBB 적용시 Dynamic Strain Aging의 영향 분석

  • 양준석;박치용;정우태;유기완;김진원
    • Proceedings of the Korean Nuclear Society Conference
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    • 1998.05b
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    • pp.305-311
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    • 1998
  • 최근들어 고려된 LBB(Leak Before Break) 적용요건중 동적파괴시힘 절차에는 울진 3&4호기 이후 파단전누설개념이 적용되는 배관이 탄소강으로 제작될 경우. 이 배관이 Dynamic Strain Aging (DSA)에 의해 파괴저항치가 감소되지 않는다는 것이 정량적으로 입증되지 않는 한, 동 배관의 파괴 물성치 결정시 DSA의 영향이 고려되어야 하며, DSA 영향을 평가하기 위해서는 동적과괴시험이 수행되어야 함을 요건화 하고 있다. 본 연구에서는 DSA 효과에 의한 파괴저항(J-R) 특성의 저하가차세대원전 원자로냉각재배관 파단전누설개넘(LBB) 적용시 설계 안전여유도에 영향을 미치지 않는 정도임을 평가하는데 있다. 따라서 ASME Section III에서 탄소강으로 분류하고 있는 강종별 파괴인성 변화를 고찰하고, 차세대원전 주냉각재배관 재료인 SA508 Class la의 최대 파괴인성 감소치를 예측하여, 울진 3&4호기에서 측정된 엘보우용 SA516-Gr.70 강의 DSA 영향 평가 결과와 비교 분석하여 차세대원전 주냉각재배관의 DSA영향을 평가하였다. 도출된 결론으로는 DSA 영향을 고려한 SA508 Class la의 J 및 dJ/dA 값은 극히 보수적으로 추정할 때 50% 이상 감소하는 것으로 예측된다. 이러한 DSA 영향을 고려하였을 경우 배관재 모재의 파괴인성치는 Weld-SAW의 J/T 값 수준으로 감소하였다. 그러나 현 LRB 해석이 가장 낮은 J/T값을 갖는 Weld-SAW Auto의 균열길이 2a인 J/T선도에 의거하여 수행되고 있다는 점을 고려한다면 비록 DSA가 배관재에 영향을 주는 가장 보수적인 값(J 및 dJ/dA값을 50% 이상)을 사용한다고 하더라도 차세대원전 LBB 적용에 문제가 되지 않음을 알 수 있다. 즉 차세대원자로 주냉각재배관에 LBB를 적용하는데는 DSA 영향은 상대적으로 중요하지 않다는 결론을 얻었다. 표면에 수소화물이 농축되어 있는 hydride layer가 형성됨을 관찰하였으며 ~5,000ppm 이상의 경우에는 수소화물의 방향성이 random하였으며 특히, ZIRLO$^{TM}$ 시편의 경우에서는 원주방향으로 길게 이어진 수소화물과 기계적 성질에 치명적인 반경방향의 수소화물이 평행하게 배열된 것을 관찰하였다.하였을 때는 Li$_2$O의 첨가에 의해 치밀화가 주로 일어났고, 반면에 $N_2$-7vol.%H$_2$ 분위기에서 소결하면 Li$_2$O의 첨가에 의해 작은 기공은 소멸되고 큰 기공이 생성되었다.지나치게 모국어의 영향만 강조하고 다른 요인들에 대해서는 다분히 추상적인 언급으로 끝났지만 이 분석을 통 해서 배경어, 목표어, 특히 중간규칙의 역할이 괄목할 만한 것임을 가시적으로 관찰할 수 있 다. 이와 같은 오류분석 방법은 학습자의 모국어 및 관련 외국어의 음운규칙만 알면 어느 학습대상 외국어에라도 적용할 수 있는 보편성을 지니는 것으로 사료된다.없다. 그렇다면 겹의문사를 [-wh]의리를 지 닌 의문사의 병렬로 분석할 수 없다. 예를 들어 누구누구를 [주구-이-ν가] [누구누구-이- ν가]로부터 생성되었다고 볼 수 없다. 그러므로 [-wh] 겹의문사는 복수 의미를 지닐 수 없 다. 그러면 단수 의미는 어떻게 생성되는가\ulcorner 본 논문에서는 표면적 형태에도 불구하고 [-wh]의미의 겹의문사는 병렬적 관계의 합성어가 아니라 내부구조를 지니지 않은 단순한 단어(minimal $X^{0}$ elements)로 가정한다. 즉, [+wh] 의미의 겹의문사는 동일한 구성요 소를 지닌 병렬적 합성어([$[W1]_{XO-}$ $[W1]_{XO}$ ]$_{XO}$)로

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Biocompatibility of porous hydroxyapatite ceramics prepared from bovine bones (소 뼈로부터 제조한 다공형 하이드록시아파타이트 세라믹스의 생체친화 특성)

  • Lee, Jong-Kook;Ko, Young-Hwa;Lee, Nan-Hee
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.22 no.3
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    • pp.139-146
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    • 2012
  • Natural hydroxyapatite powder was obtained from the calcination of bovine bones and its porous compacts were fabricated by pressureless sintering at 1100 and $1200^{\circ}C$ for 1h. To evaluate and compare their biocompatibility with porosity, we investigated the support of osteoblast cells growth and cytotoxicity using the MG-63 cell line model in vitro. Sintered hydroxyapatite ceramics have a porous microstructure with a relative density of 65 % at $1100^{\circ}C$ and 82 % at $1200^{\circ}C$. Cells adherence to the surface of hydroxyapatite ceramics was observed in a day after the cell culture, and the spreading of cytoplasm around the nucleus was shown after 3 day cell culture. Most of cells were extended to the surface of hydroxyapatite through the wide area. Cell viability was nearly the same till 3 days culturing. But the rate of cell growth is higher in the specimen sintered at $1100^{\circ}C$ than that of $1200^{\circ}C$. It indicates that the porosity is an important factor to enhance the cell viability in the porous hydroxyapatite ceramics derived from bovine bones.

Preparation of Coffee Grounds Activated Carbon-based Supercapacitors with Enhanced Properties by Oil Extraction and Their Electrochemical Properties (오일 추출에 의해 물성이 향상된 커피 찌꺼기 활성탄소기반 슈퍼커패시터 제조 및 그 전기화학적 특성)

  • Kyung Soo Kim;Chung Gi Min;Young-Seak Lee
    • Applied Chemistry for Engineering
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    • v.34 no.4
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    • pp.426-433
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    • 2023
  • Capacitor performance was considered using coffee grounds-based activated carbon produced through oil extraction and KOH activation to increase the utilization of boiwaste. Oil extraction from coffee grounds was performed by solvent extraction using n-Hexane and isopropyl alcohol solvents. The AC_CG-Hexane/IPA produced by KOH activation after oil extraction increased the specific surface area by up to 16% and the average pore size by up to 2.54 nm compared to AC_CG produced only by KOH activation without oil extraction. In addition, the pyrrolic/pyridinic N functional group of the prepared activated carbon increased with the extraction of oil from coffee grounds. In the cyclic voltage-current method measurement experiment, the specific capacitance of AC_CG-Hexane/IPA at a voltage scanning speed of 10 mV/s is 133 F/g, which is 33% improved compared to the amorphous capacity of AC_CG (100 F/g). The results show improved electrochemical properties by improving the size and specific surface area of the mesopores of activated carbon by removing components from coffee grounds oil and synergistic effects by increasing electrical conductivity with pyrrolic/pyridinic N functional groups. In this study, the recycling method and application of coffee grounds, a bio-waste, is presented, and it is considered to be one of the efficient methods that can be utilized as an electrode material for high-performance supercapacitors.

A Study on Satisfactory degree of Dental Laboratory Heads about Dental Technician Who Graduated from Junior College in Pusan (부산지역(釜山地域) 치과기공소운영자(齒科技工所運營子)의 전문대학(專門大學) 치과기공과출신(齒科技工科出身) 치과기공사(齒科技工士)에 관(關)한 만족도(滿足度) 조사(調査))

  • Lee, Myung-Kon
    • Journal of Technologic Dentistry
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    • v.10 no.1
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    • pp.55-66
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    • 1988
  • The great sudden change of circle of dental laboratory technology brought many discord between the new growing environmental group and the old group. In order to know the satisfactory degree of Dental Laboratory Heads about all and woman dental technicians who graduated from junior college, this study was conducted for 41 dental laboratory heads in Pusan area during Aug. to Sep. 1986 by means of a questionaire. The results are obtained as follows : 1. By born place, the dental laboratory heads’ satisfactory degree mean of items about all dental technician who graduated from junior college were Pusan group 3.55, Kyungnam group 2.94. The difference among the groups was significant enough(P<0.05). The satisfactory degree about woman dental technician graduated from junior college were Pusan group 3.45, Kyungnam group 2.72. 2. By age, The degree of satisfaction of items about all graduate dental technician were 30$\sim$34 age group 3.13, 40$\sim$44 age group 2.71. The degree of satisfaction about woman graduate dental technician were 30$\sim$34 age group 3.13, 40$\sim$44 age group 2.71. The degree of satisfaction about woman graduate dental technician were as follow : 35$\sim$39 age group 3.50, 45$\sim$49 age group 3.16, 30$\sim$34 age group 2.86, 40$\sim$44 age group 2.43. 3. By job career, the highest degree item out of satisfaction about all graduate dental technician was 6$\sim$10 years group 3.58, the other items were 1$\sim$15 years group 2.90, 16$\sim$20 years group 2.71. The satisfactory degree item about woman graduate dental technician was 6$\sim$10 years group 3.43, 16$\sim$20 years group 3.15, 11$\sim$15 years group 2.82 respectively. 4. By managing term of respondents’ dental laboratory, the satisfactory degree of items about all graduate dental technician were below 2 years group 3.25, 3$\sim$6 years group 3.14, 7$\sim$10 years group 2.93 in order. The satisfactory degree items about woman graduate dental technician were 11$\sim$14 years group 3.25, 3$\sim$6 years group 3.14 7$\sim$10 years group 2.80 in order. 5. By acquired qualification of licence test, the satisfactory degree of dental laboratory heads about all graduate dental technician were job career group 3.07, graduated from Dept. of Dental Technology group 3.00. The satisfactory degree about woman graduate dental technician were job career group 3.03 and graduated from Dept. of Dental Technology group 2.57. 6. By dental technician numbers of respondents’ dental laboratory. the satisfactory degree of items was as follow: 10$\sim$13 persons group is 2.86, 6$\sim$9 persons group 3.25, below 5 persons group 3.11. There was significant enough.(P<0.01). The satisfactory degree items about woman graduate dental technician were below 5 persons group is 3.00, 10$\sim$13 persons group 2.79, 6$\sim$9 persons group 2.67. 7. by the outlook of occupation, the satisfactory degree of dental laboratory heads about all dental technicians who graduated from junior college were neither good norbad group 3.20 bad group 2.59, good group 3.13. The difference among the groups was significant enough(P<0.01). The satisfactory degree about woman dental technicains graduated from junior college were good group 3.25, neither good nor bad group 2.80, bad group 2.75. The difference among the groups was significant enough.(P<0.01) 8. By occupational satisfaction, The satisfactory degree of items about all graduate dental technician were neither satisfied nor dissatisfied group 3.08, satisfied group 3.17, dissatisfied group 2.89. The satisfactional degree of items about woman graduate dental technician were satisfied group and neither satisfied mor dissatisfied group each 3.00 9. By the outlook of employment, the satisfactory degree of items about all graduate dental techician were bad group and neither good nor bad group 3.00. There was significant enough.(p<0.02) About woman graduate dental technician were good group 3.80, neither good nor bad group 3.00, bad group 2.84. The difference among the groups was significant enough.(P<0.01) 10. By cognition of the number of graduate dental technician, the satisfactory degree of dental laboratory heads about all graduate dantal technician were too many group 2.86, many group 3.32. There was significant enough.(P<0.05) About woman graduate dental techician were too many group 2.60, many group 3.20 The difference among the groups was significant enough.(P<0.01) 11. As compared with the items ut of satisfaction and improvement about all dental technician who graduated from junior college, the rate of satisfaction item was for as follow : dental technological theory is 5.21%, ability of adaptation and sincerity each 17.1%. The rate of improvement items was as follow : sincerity is 39%, ability of work and ability of basical work each 24.4%. 12. As compared with the items out of satisfaction and improvement about woman dental laboratory technician who graduated from junior college, the rate of satisfaction item was as follow : atmosphere of the office is 56.1%, sincerity 22%. The rate of improvement items was as follow : ability of adaptation is 36.6%, ability of work 31.7%.

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Development of the impregnated dispenser cathode for thermionic emission electron gun

  • Hong, Yong-Jun;Lee, Seong;Sin, Jin-U
    • Proceedings of the Korean Vacuum Society Conference
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    • 2016.02a
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    • pp.182.1-182.1
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    • 2016
  • 전자빔의 운동에너지를 변화시켜 전자기장을 발생시키는 진공튜브 장치는 기본적으로 전자빔 발생부인 전자총을 핵심 구성부로 사용한다. 이러한 전자총을 이용하는 진공튜브로는 핵융합을 위해 플라즈마 가열용의 RF를 발생시키는 자이로트론 튜브와 방사광 가속기에서 전자를 가속시키는데 이용되는 클라이스트론 튜브 등이 있으며, 군사적으로는 레이더를 비롯하여 유도미상일에 들어가는 탐색기, 전투기에서 사용되는 송수신용 마이크로파 발생장치 등의 핵심부품인 진행파관 진공튜브 등이 있다. 이러한 응용분야에서는 기본적으로 고출력의 전자파를 필요로 하기 때문에 반도체를 이용한 장치로는 그 성능을 구현할 수 없다. 따라서 열음극을 사용하는 전자총을 기반으로 한 다양한 형태의 진공튜브 장치가 주로 이용되고 있다. 현재 고출력 마이크로파 진공튜브용 열음극 전자총은 대부분 외국에서 수입하고 있는데 그 이유는 전자총의 핵심 부품인 열음극 캐소드를 국내에서 개발하지 못하였기 때문이다. 하지만 본 연구에서는 텅스텐 기반의 함침형 열음극 캐소드를 국내에서 자체 개발하는데 성공하였다. 전통적으로 미국에서 개발해온 함침형 열음극 캐소드는 텅스텐 소결체에 기공을 학보하고 여기에 Ba을 중심으로 한 알칼리성 물질들을 일정비율로 혼합하여 함침한 것으로 일함수 2.1~2.3 eV 수준의 물성을 갖는다. 이에 따라 방출할 수 있는 전류의 양은 운용 온도 $1000^{\circ}C$ 정도에서 전류밀도로 대략 수 $A/cm^2$ 수준이다. 본 연구에서 개발한 캐소드는 S-type으로 알려진 것으로 BaO : CaO : $Al_2O_3$ = 4 : 1 : 1 비율로 함침되었다. 고진공장치에서 전류측정 결과 $1040^{\circ}C$에서 $10.6A/cm^2$의 전류밀도를 기록하였으며 이에 대하여 Richardson-Dushman equation으로 계산하였을 때, 약 1.9 eV의 일함수를 갖는 것을 알 수 있었다. 이는 현재 많은 응용분야에서 사용하고 있으며 함침형 캐소드에 Os이나 Ir 등의 물질을 코팅하여 일함수를 낮추고 전류밀도를 향상시킨 M-type 캐소드의 결과와 유사한 수준이다.

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