• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2004년도 추계학술대회논문집
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• pp.294-297
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• 2004

RTP(Rapid Thermal Pressing) is to fabricate desired pattern on polymer substrate by pressing patterned mold against the substrate heated around glass transition temperature. For a successful RTP process, the whole process including heating, molding, cooling and demolding should be conducted 'rapidly' as possible. As the RTP process is effective in replicating patterns on flat large surface without causing shape distortion after cooling, it is being widely used for fabricating various micro/bio application components, especially with channel-type microstructures on surface. This investigation finally aims to develop a RTP process machine for mass-producing micro/bio application components. As a first step for that purpose, we intended to examine the technological difficulties for realizing mass production by RTP process. Therefore, in the current paper, 4 kinds of RTP machines were examined and then the RTP process was conducted experimentally for PMMA film by using one of the machines, HEX 03. The micro-patterned molds used for RTP experiment was fabricated from silicon wafer by semi-conduct process. The replicated micro patterns on PMMA films were examined using SEM and the causes of defect observed in the replicated patterns were discussed.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제42회 동계 정기 학술대회 초록집
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• pp.557-557
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• 2012

Silicatein-${\alpha}$, the enzyme extracted from silica spicules in glass sponges, has been studied extensively in the way of chemistry from 1999, in which the pioneering work by Morse, D. E. - the discovery of the enzymatic hydrolysis in Silicatein-${\alpha}$ - was published. Since its reaction conditions are physiologically favored, synthesis of various materials, such as gallium oxide, zirconium oxide, and silicon oxide, was achieved without any hazardous wastes. Although some groups synthesized oxide films and particles, they have not achieved yet controlled morphogenesis in the reaction conditions mentioned above. With the knowledge of catalytic triad involved in hydrolysis of silicone alkoxide and oligomerization of silicic acid, we designed the novel peptide amphiphiles to not only form self-assembled structure, but also display similar activities to silicatein-${\alpha}$. Designed templates were able to self-assemble into left-handed helices for the peptide amphiphiles with L-form amino acid, catalyzing polycondensation of silicic acids onto the surface of them. It led to the formation of silica helices with 30-50 nm diameters. These results were characterized by various techniques, including SEM, TEM, and STEM. Given the situation that nano-bio-technology, the bio-applicable technology in nanometer scale, has been attracting considerable attention; this result could be applied to the latest applications in biotechnology, such as biosensors, lab-on-a-chip, biocompatible nanodevices.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.422.1-422.1
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• 2016

Graphene quantum dots (GQDs), a new kind of carbon-based photo luminescent nanomaterial from chemically modified graphene oxide (CMGO) or chemically modified graphene (CMG), has attracted extensive research attention in the last few years due to its outstanding chemical, optical and electrical properties. To further extended its potential applications as optoelectronic devices, solar cells, bio and bio-sensors and so on, intensive research efforts have been devoted to the CMG. However, the CMG, a suspension of aqueous, have problematic since they are prone to agglomeration after drying a solvent. In this study, we synthesized the GQDs from graphite and deposited on silicon substrate by kinetic spray. The photo luminescent properties of deposited GQD films were analyzed and compared with initial GQDs suspension. In addition, its carbon properties were investigated with GQDs solution properties. The properties of deposited GQD films by kinetic spray were similar to that of the GQDs suspension in water. We could provide a pathway for silicon-based silicon based device applications. Finally, the well-adjusted GQD films with photo luminescence effects will show Energy-Down-Shift layer effects on silicon solar cells. The GQD layers deposited at nozzle scan speeds of 40, 30, 20, and 10 mm/s were evaluated after they were used to fabricate crystalline-silicon solar cells; the results indicate that GQDs play an important role in increasing the optical absorptivity of the cells. The short-circuit current density (Jsc) was enhanced by about 2.94 % (0.9 mA/cm2) at 30 mm/s. Compared to a reference device without a GQD energy-down-shift layer, the PCE of p-type silicon solar cells was improved by 2.7% (0.4 percentage points).

• 생물환경조절학회지
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• 제17권1호
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• pp.32-37
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• 2008

참외 재배시설에서 시설 내부 필름 표면에 결로현상으로 부착된 수적량과 시설 외부 필름 표면에 부착된 분진 부착량이 적었던 PO-2에서 투광률이 71.2%로 가장 높았다. 겨울철 시설 터널에서 온도가 가장 낮은 새벽 시간의 기온은 노지보다 $11.8{\sim}14.5^{\circ}C$ 정도 높게 나타났으며, 피복자재에 따라서는 최고 $2.7^{\circ}C$차이가 났는데 PO-2에서 가장 높았다. 지온은 터널이 노지보다 $13.0{\sim}15.3^{\circ}C$ 정도 높았으며, PO-2에서 가장 높아 PE보다 $2.3^{\circ}C$ 높았다. 참외 과실 전체에서 엽산을 분석한 결과 엽산함량은 품종에 따라 $68.9{\sim}113.4{\mu}g/100g$ 정도로 나타났다. 저온기에 참외 과육에서 $45{\sim}53{\mu}g/100g$ 정도로 나타났으며, 보온성과 광환경이 우수한 PO-2에서 PE보다 17% 정도 높은 수준을 보였다. 그러나 외기 온도가 $15^{\circ}C$ 이상 확보된 시기에는 $55.2{\sim}75.2{\mu}g/100g$ 정도로 나타났으며, PO-2에서 PE보다 과육에서 36% 높은 수준을 보였다.

• 생물환경조절학회지
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• 제16권3호
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• pp.167-173
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• 2007

참외 재배시설의 광 환경 개선을 위하여 필름두께, 자외선 차단율, 적외선 흡수율이 다른 PO계 필름 3종(J-1, J-2, J-3), PE 필름(K-1, K-2, K-3)을 비교하여 참외를 재배한 결과는 다음과 같다. 재배지역과 품종에 따라 다소의 차이는 있으나 오복꿀참외의 경우, K-3의 당도는 $14.3^{\circ}Brix$이고 J-3, J-2에서는 이보다 각각 $1.3^{\circ}Brix,\;0.8^{\circ}Brix$ 정도 높은 경향이었다. 과피의 색도(a 값)는 K-3의 0.5에 비하여 J-3, J-1, J-2에서 각각 3.3, 2.3, 1.9 정도 더 높았다. 또한 J-1, J-2, J-3 처리구에서 발효과율 및 기형과율이 감소하였고 상품과 율은 증가하였다. 10a당 상품수량은 K-3의 1,622 kg에 비하여 J-1, J-3, J-2에서 각각 31.2%, 23.8%, 18.5%증가하였다. 이상의 결과로 볼 때 J-1, J-2, J-3등의 polyolefin계 필름은 필름두께가 두껍고 적외선 흡수율이 높아 보온효과가 우수하였으며 이로 인하여 과실의 당도가 증가하고 색도가 우수한 것으로 생각된다. 또한 발효과 발생이 감소하고 상품과율이 증가하는 등 품질이 향상되었고 수량도 증가되었다.

• 마이크로전자및패키징학회지
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• 제22권4호
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• pp.83-89
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• 2015

본 논문에서는 졸-침투와 직접-패턴 공정을 이용하여 향상된 압전 후막의 전기적 특성과 우수한 패터닝 특성을 동시에 만족할 수 있는 제작 방법을 제시한다. 저온(< $850^{\circ}C$) 공정 후 후막의 고밀도 및 직접-패턴의 목적을 달성하기 위해서, 감광성 티탄산 지르콘산 연 ($Pb(Zr,Ti)O_3$, PZT) 졸을 스크린인쇄된 PZT 후막 내부로 침투시켰다. 직접-패턴된 PZT막은 포토크롬마스크와 UV 조사에 의해서 일정한 간격으로 인쇄된 후막 위에 성공적으로 형성되었다. 스크린인쇄된 후막은 분말형태의 기공성 구조를 갖고 있어 조사된 UV빛이 산란되기 때문에, 감광성 졸-침투 공정을 할 때 PZT 후막의 특성을 증가시키기 위한 공정의 최적화가 필요하다. 침투된 감광성 PZT 졸의 농도, 조사된 UV 시간 및 용매 현상 시간을 최적화한 결과, 0.35 M의 PZT 농도, 4 분의 UV 조사시간과 15 초의 용매 현상시간으로 졸-침투된 PZT 후막은 $800^{\circ}C$ 소결 온도에서 입자들의 성장에 의해 치밀화 정도가 증가되었다. 또한 PZT후막의 강유전 특성(잔류분극 및 항복 전압)도 향상되었다. 특히 잔류분극값은 스크린인쇄된 후막보다 약 4배정도 증가되었다. 이렇게 제작된 후막은 어레이타입의 압전형 마이크로미터크기의 센서 및 액츄에이터 등에 응용 가능성을 제시할 수 있었다.

• 한국표면공학회지
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• 제48권2호
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• pp.43-49
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• 2015

This study reports a fabrication of $TiO_2$ on the surface of dental implants by pulsed d.c. magnetron sputtering from a Ti target. A systematic investigation on the microstructure and mechanical properties of $TiO_2$ films was carried out with the variation of $O_2$ contents and substrate temperatures. The effects of deposition parameters on the fabricated structures were investigated by X-ray diffraction (XRD) technique and field emission scanning electron microscope (FE-SEM). Hydrophilic properties were evaluated by measuring water contact angles on the film surface. With increasing $O_2$ contents up to 40%, surface roughness of $TiO_2$ film increased while relatively smooth surface was obtained with 50% $O_2$ contents. Surface roughness and adhesion strength both increased as substrate temperature increased up to $200^{\circ}C$. From these results, hydrophilic and adhesive properties of the present $TiO_2$ films synthesized with 40% $O_2$ at $200^{\circ}C$ are regarded to be suitable for bio-compatible applications.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.505-505
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• 2011

The control of wettability of thin films is of great importance and its success surely brings us huge applications such as self-cleaning, antifogging and bio-passive treatments. Usually, the control is accomplished by modifying either surface energy or surface topography of films. In general, hydrophobic surface can be produced by coating low surface energy materials such as fluoropolymer or by increasing surface roughness. In contrast, to enhance the hydrophillicity of solid surfaces, high surface energy and smoothness are required. Silica (SiO2) is environmentally safe, harmless to human body and excellently inert to most chemicals. Also its chemical composition is made up of the most abundant elements on the earth's crest, which means that SiO2 is inherently economical in synthesis. Moreover, modification in chemistry of SiO2 into various inorganic-organic hybrid materials and synthesis of films are easily undertaken with the sol-gel process. The contact angle of water on a flat silica surface on which the Young's equation operates shows ~50o. This is a slightly hydrophilic surface. Many attempts have been made to enhance hydrophilicity of silica surfaces. In recent years, superhydrophilic and antireflective coatings of silica were fabricated from silica nanoparticles and polyelectrolytes via a layer-by-layer assembly and postcalcination treatment. This coating layer has a high transmittance value of 97.1% and a short water spread time to flat of <0.5 s, indicating that both antireflective and superhydrophilic functions were realized on the silica surfaces. In this study, we assessed hydrophillicity and hydrophobicity of silica coating layers that were synthesized using the sol-gel process. Systematic changes of processing parameters greatly influence their surface properties.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.105-106
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• 2013

Surface plasmon resonance (SPR) is classified into the propagating surface plasmon (PSP) excited on flat metal surfaces and the local surface plasmon (LSP) excited by metalnanoparticles. It is known that fluorescence signals are enhanced by these two SPR-fields.On the other hand, fluorescence is quenched by the energy transfer to metal (FRET). Bothphenomena are controlled by the distance between dyes and metals, and the degree offluorescence enhancement is determined by the correlation. In this study, we determined thecondition to achieve the maximum fluorescence enhancement by adjusting the distance of ametal nanoparticle 2D sheet and a quantum dots 2D sheet by the use of $SiO_2$ spacer layers. The 2D sheets consisting of myristate-capped Ag nanoparticles (AgMy nanosheets) wereprepared at the air-water interface and transferred onto hydrophobized gold thin films basedon the Langmuir-Schaefer (LS) method [1]. The $SiO_2$ sputtered films with different thickness (0~100 nm) were deposited on the AgMy nanosheet as an insulator. TOPO-cappedCdSe/CdZnS/ZnS quantum dots (QDs, ${\lambda}Ex=638nm$) [2] were also transferred onto the $SiO_2$ films by the LS method. The layered structure is schematically shown in Fig. 1. The result of fluorescence measurement is shown in Fig. 2. Without the $SiO_2$ layer, the fluorescence intensity of the layered QD film was lower than that of the original QDs layer, i.e., the quenching by FRET was predominant. When the $SiO_2$ thickness was increased, the fluorescence intensity of the layered QD film was higher than that of the original QDs layer, i.e., the SPR enhancement was predominant. The fluorescence intensity was maximal at the $SiO_2$ thickness of 20 nm, particularly when the LSPR absorption wavelength (${\lambda}=480nm$) was utilized for the excitation. This plasmonic nanosheet can be integrated intogreen or bio-devices as the creation point ofenhanced LSPR field.

• 한국식품저장유통학회지
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• 제15권3호
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• pp.347-351
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• 2008

미세천공 포장재가 신선절단 사과의 품질유지에 미치는 영향을 확인하기 위하여, 원형사과(Malus domestica Borkh. cv. Red Delicious)를 제심, 절단한 후 레이저로 미세공을 하나 천공한 것과 천공하지 않은 polyolefin 필름으로 밀봉 포장하고 $4^{\circ}C$에서 3주간 저장하면서 이화학적 품질 특성들의 변화를 조사하였다. 절단사과의 과육경도는 저장 1주 후부터 천공포장구에서 유의적으로 높은 값은 보였고, 가용성 고형분 함량은 저장 3주 후에 천공포장구에서 유의적으로 높은 값을 보였다. 절단사과의 절단면 갈변도, 적정산도, pH, 아세트알데하이드 및 에탄올 함량은 두 종류의 포장구간에 유의적인 차이를 보이지 않은 것으로 나타났다. 이로써 미세천공 포장재는 신선절단 사과의 과육경도 유지에 효과적인 방법인 것으로 판단된다.