High-harmonic generation by resonant plasmon field enhancement

Kim, Seungchul,Jin, Jonghan,Kim, Young-Jin,Park, In-Yong,Kim, Yunseok,Kim, Seung-Woo Nature Publishing Group 2008 Nature Vol.453 No.7196

High-harmonic generation by focusing a femtosecond laser onto a gas is a well-known method of producing coherent extreme-ultraviolet (EUV) light. This nonlinear conversion process requires high pulse intensities, greater than 10<SUP>13</SUP> W cm<SUP>-2</SUP>, which are not directly attainable using only the output power of a femtosecond oscillator. Chirped-pulse amplification enables the pulse intensity to exceed this threshold by incorporating several regenerative and/or multi-pass amplifier cavities in tandem. Intracavity pulse amplification (designed not to reduce the pulse repetition rate) also requires a long cavity. Here we demonstrate a method of high-harmonic generation that requires no extra cavities. This is achieved by exploiting the local field enhancement induced by resonant plasmons within a metallic nanostructure consisting of bow-tie-shaped gold elements on a sapphire substrate. In our experiment, the output beam emitted from a modest femtosecond oscillator (100-kW peak power, 1.3-nJ pulse energy and 10-fs pulse duration) is directly focused onto the nanostructure with a pulse intensity of only 10<SUP>11</SUP> W cm<SUP>-2</SUP>. The enhancement factor exceeds 20 dB, which is sufficient to produce EUV wavelengths down to 47 nm by injection with an argon gas jet. The method could form the basis for constructing laptop-sized EUV light sources for advanced lithography and high-resolution imaging applications.

특허 받은 소변컵을 이용하여 채집한 첫 소변과 중간소변 시료의 비교 평가

김승철(SeungChul Kim),김호성(HoSung Kim),김창욱(ChangUook Kim),표상신(SangShin Pyo) 한국콘텐츠학회 2022 한국콘텐츠학회논문지 Vol.22 No.6

일반적으로 의료기관에서 요로감염을 확인하기 위한 방법으로 요검사(urinalysis)와 항균제 감수성 검사가 포함된 소변배양(urine culture)을 시행한다. 소변 검체는 채집하기 전에 요도 및 회음부 주변을 소독하는 것이 중요하며, 첫 소변이 아닌 중간소변으로 채집하는 것이 중요하다. 첫 소변과 중간소변을 자동으로 쉽게 분리할 수 있는 특허컵(특허 제10-1732843호)을 발명하였고 이를 이용하여 특허컵과 일반컵을 비교 평가하였다. 특허컵으로 분리한 첫 소변(N=24), 중간소변(N=24)의 nitrite (P <0.001), WBC (P =0.005), 세균 colony수 (P =0.001), colony 양성률 (P =0.004) 으로 유의한 높은 수치를 얻었다. 이는 특허컵을 이용하여 분리한 첫 소변과 중간소변이 잘 분리되었음을 알 수 있다. 또한 특허컵을 이용하여 분리한 중간소변(N=24)이 일반컵을 이용하여 채집한 중간소변(N=24) 보다 세균 colony 수가 통계적으로 유의하게 많았다(평균 7.9개 vs 평균 4.0개, P =0.002). 이는 특허컵을 이용하여 분리한 중간소변이 일반컵을 이용하여 채집한 중간소변 보다 요로감염검사에 대해 민감도(sensitivity)가 높다는 것을 의미한다. In general, as a method to confirm a urinary tract infection (UTI) in a medical institutions, urine culture including a urinalysis and an antimicrobial susceptibility test is performed. It is important to disinfect the area around the urethra and perineum before collecting urine samples, and it is important to collect it intermediate urine, not the first-void urine. We invented a patent urine cup (Patent No. 10-1732843) that can automatically and easily separate first-void urine and midstream urine and using this, the patent cup and the general cup were compared and evaluated using this. Nitrite (P <0.001), WBC (P =0.005), Bacterial colony count (P =0.001), colony positivity rate (P =0.004) in first-void urine (N=24), midstream urine (N=24) separated by patent cup to obtain a significantly higher value. This can be seen from the fact that the first-void urine and midstream urine separated using the patent cup were well separated. Also, the number of Bacterial colonies was statistically significantly higher in the midstream urine isolated using a patent cup (N=24) than in the midstream urine collected using a general cup (N=24) (average 7.9 vs. 4.0 on average, P = 0.002). Which means that the midstream urine separated using the patent cup is more sensitive to the UTI test than the midstream urine collected using a general cup.

밸브안착속도가 LPG엔진 밸브계 거동에 미치는 영향에 관한 연구

김승철(SeungChul Kim),김청균(ChungKyun Kim),이경식(KyoungSik Lee),이한열(HanYeol Lee),김상구(SangGoo Kim) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

Due to better emission for CO2 and fine dust (PM10) than diesel and gasoline vehicles, LPG engine that is called low pollutant one is recently adopted for passenger car as well as commercial one and its demand gets growing year by year. The main part that should be replaced in the existing gasoline engine because of the lack of durability is intake and exhaust valves and their seats. This is because LPG has lower lubrication capability than gasoline and also supplying combustion chamber with gas state makes the durability of valve system weaker. Furthermore higher thermal load on exhaust valve system and the lack of combustion products are very tough conditions for adhesive wear. In this point, the effect on adhesive wear through the measurement of behavior change of valves according to seating has been evaluated and the solution to decrease it has been searched. So this study searched the behavior change of valve seating velocity through the redesign of cam profile ramp and confirmed the change of valve seating velocity contributed to decreasing engine wear and its noise.

Experimental Study on the Characteristics of Sprinkler Discharge Obstructions in Upper Logistic Rails

Hyounsu Kim(Hyounsu Kim),Jihyun Kwark(Jihyun Kwark),Seungchul Lee(Seungchul Lee) 한국화재소방학회 2023 International Journal of Fire Science and Engineer Vol.37 No.2

In the early stage of a fire, sprinklers system of water-based fire-extinguishing systems, which are harmless to the human body, are the most widely used for fire control and suppression in manufacturing factories. The logistic carrier transport in modern manufacturing companies has been almost fully automated and sprinklers are installed around them all over the world. In the presence of an obstruction, a base plate around the upper logistic rail secures the separation distance from the obstacle of more than three times the width of the obstacle, as required by fire regulations (National Fire Technical Code 103 and National Fire Protection Association 13). However, if this cannot be achieved, the fire sprinkler should be more than 600 mm from the base plate, and the opening ratio of the base plate should be less than 70% in an upper logistic rail. This requires sprinklers to be positioned away from obstructions at a minimum of three times the maximum dimension of the obstruction. This study analyzed the sprinkler discharge obstruction from the base plate around the upper logistic rail using the UL standard for sprinkler water spray for the logistic rail area of manufacturing factories. The results can contribute to mitigating fire risks and safety problems.

강원도 논콩 재배단지의 토양화학성

윤병성(Byeongsung Yoon),최승출(Seungchul Choi),김세원(Sewon Kim),서영호(Youngho Seo),김인종(Injong Kim),김경희(Kyunghi Kim),김재록(Jaerok Kim),조병곤(Byunggon Jo),김병진(Byoungjin Kim) 한국토양비료학회 2013 한국토양비료학회 학술발표회 초록집 Vol.2013 No.5

디젤 엔진에서 밸브 스템계의 표면 조도에 따른 오일 누설 특성에 관한 실험적 연구

이일권(Ilkwon Lee),김시영(Siyoung Kim),국창호(Changho Kook),김청균(Chungkyun Kim),김도현(Dohyun Kim),김승철(Seungchul Kim),김한구(Hangoo Kim),문학훈(Hakhoon Moon) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

This paper is for study on the leakage including with surface roughness in the valve stem system of diesel engine. This paper is for study on the oil leakage including with surface roughness in the valve stem system of diesel engine. In the leakage 1, the surface roughness was very dense, but leakage quantity of oil showed growing a trend. In the leakage 1 and 2, when the surface roughness was more scabrous, the control of oil leakage verified that fact is more advantageous. In the leakage 3, the sample verified more favorable for control of oil leakage that the surface roughness of valve stem was not soft. The experimental result of leakage 4 verified that lost a pocket effect that is a role for oil storage existing in the range of surface roughness in leakage 3. As a result, the oil leakage quantity knew increasing a tendency. In the showing from this experimental results, the condition of surface roughness being the most suitable for oil leakage control can conclude with 0.26~0.48㎛.

Dissimilar anisotropy of electron versus hole bulk transport in anatase TiO2 : Implications for photocatalysis

Kim, Donghun,Yeo, Byung Chul,Shin, Dongbin,Choi, Heechae,Kim, Seungchul,Park, Noejung,Han, Sang Soo American Physical Society 2017 Physical Review B Vol.95 No.4

<P>Recent studies on crystal facet manipulation of anatase TiO2 in photocatalysis have revealed that reduction and oxidation reactions preferably occur on (100)/(101) and (001) facets, respectively; however, a fundamental understanding of their origin is lacking. Here, as a result of first-principles calculations, we suggest that a dissimilar trend in the anisotropy of electron vs hole bulk transport in anatase TiO2 can be a dominant underlying mechanism for the difference in photochemical activity. Photoexcited electrons and holes are driven to different facets, i.e., electrons on (100)/(101) and holes on (001), leading to the observed preference for either reduction or oxidation. This trend of electrons vs holes found in pure TiO2 applies even for cases where a variety of dopants or defects is introduced.</P>

Measuring elastic modulus of bacterial biofilms in a liquid phase using atomic force microscopy

Kim, Yong-Min,Kwon, Tae-Hyuk,Kim, Seungchul Techno-Press 2017 Geomechanics & engineering Vol.12 No.5

With the increasing interest in using bacterial biofilms in geo-engineering practices, such as soil improvement, sealing leakage in earth structures, and hydraulic barrier installation, understanding of the contribution of bacterial biofilm formation to mechanical and hydraulic behavior of soils is important. While mechanical properties of soft gel-like biofilms need to be identified for appropriate modeling and prediction of behaviors of biofilm-associated soils, elastic properties of biofilms remain poorly understood. Therefore, this study investigated the microscale Young's modulus of biofilms produced by Shewanella oneidensis MR-1 in a liquid phase. The indentation test was performed on a biofilm sample using the atomic force microscopy (AFM) with a spherical indentor, and the force-indentation responses were obtained during approach and retraction traces. Young's modulus of biofilms was estimated to be ~33-38 kPa from these force-indentation curves and Hertzian contact theory. It appears that the AFM indentation result captures the microscale local characteristics of biofilms and its stiffness is relatively large compared to the other methods, including rheometer and hydrodynamic shear tests, which reflect the average macro-scale behaviors. While modeling of mechanical behaviors of biofilm-associated soils requires the properties of each component, the obtained results provide information on the mechanical properties of biofilms that can be considered as cementing, gluing, or filling materials in soils.

Performance Measurement of a Photodiode Sensor Coupled with a Scintillator

Kim, Bobae,Kang, Kookhyun,Kim, Taehun,Kim, Hongjoo,Park, Hwanbae,Lee, Seungchul,Jeon, Hyebin Korean Physical Society 2016 New Physics: Sae Mulli Vol.66 No.3

A systems approach for identifying resistance factors to Rice stripe virus.

Kim, Kangmin,Choi, Daeseok,Kim, Sang-Min,Kwak, Do-Yeon,Choi, Jaemyung,Lee, Seungchul,Lee, Bong-Choon,Hwang, Daehee,Hwang, Ildoo APS Press 2012 Molecular plant-microbe interactions Vol.25 No.4

<P>Rice stripe virus (RSV) causes disease that can severely affect the productivity of rice (Oryza sativa). Several RSV-resistant cultivars have been developed. However, host factors conferring RSV resistance in these cultivars are still elusive. Here, we present a systems approach for identifying potential rice resistance factors. We developed two near-isogenic lines (NIL), RSV-resistant NIL22 and RSV-susceptible NIL37, and performed gene expression profiling of the two lines in RSV-infected and RSV-uninfected conditions. We identified 237 differentially expressed genes (DEG) between NIL22 and NIL37. By integrating with known quantitative trait loci (QTL), we selected 11 DEG located within the RSV resistance QTL as RSV resistance factor candidates. Furthermore, we identified 417 DEG between RSV-infected and RSV-uninfected conditions. Using an interaction network-based method, we selected 20 DEG highly interacting with the two sets of DEG as RSV resistance factor candidates. Among the 31 candidates, we selected the final set of 21 potential RSV resistance factors whose differential expression was confirmed in the independent samples using real-time reverse-transcription polymerase chain reaction. Finally, we reconstructed a network model delineating potential association of the 21 selected factors with resistance-related processes. In summary, our approach, based on gene expression profiling, revealed potential host resistance factors and a network model describing their relationships with resistance-related processes, which can be further validated in detailed experiments.</P>