• Nuclear Engineering and Technology
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• 제41권8호
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• pp.1101-1108
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• 2009

The ocean contains around eighty elements of the periodic table and uranium is also one among them, with a uniform concentration of 3.3 ppb and a relative abundance factor of 23. With a large coastline, India has a large stake in exploiting the 4 billion tonnes of uranium locked in seawater. The development of radiation grafting techniques, which are useful in incorporating the required functional groups, has led to more efficient adsorbent preparations in various geometrical configurations. Separation based on a polymeric adsorbent is becoming an increasingly popular technique for the extraction of trace heavy metals from seawater. Radiation grafting has provided definite advantages over chemical grafting. Studies related to thermally bonded non woven porous polypropylene fiber sheet substrate characterization and parameters to incorporate specific groups such as acrylonitrile (AN) into polymer back bones have been investigated. The grafted polyacrylonitrile chains were chemically modified to convert acrylonitrile group into an amidoxime group, a chelating group responsible for heavy metal uptake from seawater/brine. The present work has been undertaken to concentrate heavy metal ions from lean solutions from constant potential sources only. A scheme was designed and developed for investigation of the recovery of heavy metal ions such as uranium and vanadium from seawater.

• 한국구조물진단유지관리공학회 논문집
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• 제17권6호
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• pp.138-144
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• 2013

비노출형 도막방수재 도포 후 누름콘크리트 타설 시기에 따른 도막방수재의 물리적 특성과 바탕면 조건, 도막두께 및 보강포 사용유무에 따른 내피로성을 검토하였는데, 누름콘크리트 타설 시기가 짧을수록 변색이 심하였고, 도막두께가 두꺼운 반면 인장성능이 낮았다. 내피로 성능은 3 mm의 도막두께에서는 파단되지 않았으나 1, 2 mm는 모두 파단 되었고 부직포로 보강한 경우의 내피로성능이 상대적으로 우수한 것으로 나타났다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.320-320
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• 2011

We describe fabrication of superhydrophobic surface on non-woven fabric (NWF) having nano-hairy structures and a hydrophobic surface coating. Oxygen plasma was irradiated on NWF for nano-texuring and a precursor of HMDSO (Hexamethydisiloxane) was introduced as a surface chemical modification for obtaining superhydrophobicity using 13.56 MHz radio frequency-Plasma Enhanced Chemical Vapor Deposition (rf-PECVD). O2 plasma treatment time was varied from 1 min to 60 min at a bias voltage of 400V, which fabricated pillar-like structures with diameter of 30 nm and height of 150 nm on NWF. Subsequently, hydrophobic coating using hexamethyldisiloxane vapor was deposited with 10 nm thickness on NWF substrate at a bias voltage of 400 V. We evaluate superhydrophobicity of the modified NWF with sessile drop using goniometer and high speed camera, in which aspect ratio of nanohairy structures, contact angle and contact angle hysteresis of the surfaces were measured. With the increase of aspect ratio, the wetting angle increased from $103^{\circ}$ to $163^{\circ}$, and the contact angle hysteresis decreased dramatically below $5^{\circ}$. In addition, we had conducted experiment for nucleation and condensation of water via E-SEM. During increasing vapor pressure inside E-SEM from 3.7 Torr to over 6 Torr which is beyond saturation point at $2^{\circ}C$, we observed condensation of water droplet on the superhydropobic NWF. While the condensation of water on oxygen plasma treated NWF (superhydrophilic) occurred easily and rapidly, superhydrophobic NWF which was fabricated by oxygen and HMDSO was hardly wet even under supersaturation condition. From the result of wetting experiment and water condensation via E-SEM, it is confirmed that superhydrophobic NWF shows the grate water repellent abilities.

• Journal of Electrical Engineering and Technology
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• 제12권1호
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• pp.317-328
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• 2017

This paper presents design and specific absorption rate analysis of a 2.4 GHz wearable patch antenna on a conventional and electromagnetic bandgap (EBG) ground planes, under normal and bent conditions. Wearable materials are used in the design of the antenna and EBG surfaces. A woven fabric (Zelt) is used as a conductive material and a 3 mm thicker Wash Cotton is used as a substrate. The dielectric constant and tangent loss of the substrate are 1.51 and 0.02 respectively. The volume of the proposed antenna is $113{\times}96.4{\times}3mm^3$. The metamaterial surface is used as a high impedance surface which shields the body from the hazards of electromagnetic radiations to reduce the Specific Absorption Rate (SAR). For on-body analysis a three layer model (containing skin, fats and muscles) of human arm is used. Antenna employing the EBG ground plane gives safe value of SAR (i.e. 1.77W/kg<2W/kg), when worn on human arm. This value is obtained using the safe limit of 2 W/kg, averaged over 10g of tissue, specified by the International Commission of Non Ionization Radiation Protection (ICNIRP). The SAR is reduced by 83.82 % as compare to the conventional antenna (8.16 W/kg>2W/kg). The efficiency of the EBG based antenna is improved from 52 to 74 %, relative to the conventional counterpart. The proposed antenna can be used in wearable electronics and smart clothing.

• 한국조경학회지
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• 제40권2호
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• pp.130-137
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• 2012

본 연구는 유기질 비료와 멀칭재에 따른 리아트리스(Liatrisspicata)의 생육을 조사하여 무관수 옥상녹화에서의 효용성을 알아보고자 실시하였다. 4가지의 멀칭처리(무처리, 난석 멀칭, 바크 멀칭, 검은색 부직포 멀칭)와 3가지의 유기질 비료처리($A_1O_0$, $A_4O_1$, $A_1O_1$)로 총 12가지의 처리구를 옥상에 배치하였다. 생육측정은 2010년 4월부터 10월까지 초장, 엽수, 꽃대직경, 소화수, 엽록소 함량, 지상부 생체중 및 건조중 등을, 생존율은 이듬해인 2011년 5월에 조사하였다. 1. 인공배합토 100%($A_1O_0$)처리구의 경우, 검은색 부직포 멀칭에서 리아트리스의 엽수, 소화수, 엽록소 함량 등이 높았고, 특히, 초장, 지상부 생체중, 지상부 건조중 등은 다른 멀칭처리에 비해 확연한 차이를 보였다. 동면 후 생존율은 무처리와 난석 멀칭이 100%, 바크 멀칭에서는 20%,검은색 부직포 멀칭에서는 0%의 생존율을 보였다. 2.인공배합토 80%, 유기질 비료 20%($A_4O_1$)의 경우, 검은색 부직포 멀칭에서 리아트리스의 초장, 엽수, 소화수, 지상부, 생체중, 지상부 건조중 등이 다른 멀칭처리에 비해 높았으나, 초장을 제외하고 뚜렷한 차이를 보이지 않았다. 동면 후 생존율은 $A_1O_0$와 비교해볼 때 약 40~60% 정도 감소하였다. 3. 인공배합토 50%, 유기질 비료 50%($A_1O_1$)의 경우, 검은색 부직포 멀칭이나 바크 멀칭에서 리아트리스의 초장, 꽃대직경, 소화수, 엽수, 엽록소 함량, 지상부 생체중, 지상부 건조중 등이 다른 멀칭처리에 비해 좀 더 높았으나 통계적인 유의성은 없었다. 동면 후 생존율은 모든 멀칭처리에서 0%를 나타냈다. 따라서, 무관수 옥상녹화에서 리아트리스의 생육과 개화는 검은색 부직포 멀칭에서 가장 양호하였다. 반면, 동면 후 생존율은 유기질 비료의 비율이 높을수록 저하되는 경향을 보였다.