• Bulletin of the Korean Chemical Society
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• v.31 no.12
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• pp.3593-3599
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• 2010

In an original effort, this lab attempted to employ polystyrene nanoparticles as a template for the synthesis of ordered and highly porous macroporous $SiO_2$ thin films, utilizing their high combustion temperature and narrow size distribution. However, polystyrene nanoparticle thin films were not obtained due to the low interaction between individual particles and between the particle and silicon substrate. However, polystyrene-polyacrylic acid (PS-AA) colloidal particles of a core-shell structure were synthesized by a one-pot miniemulsion polymerization approach, with hydrophilic polyacrylic acid tails on the particle surface that improved interaction between individual particles and between the particle and silicon substrate. The PS-AA thin films were spin-coated in the thickness ranges from monolayer to approximately $1.0\;{\mu}m$. Using the PS-AA thin films as sacrificial templates, macroporous $SiO_2$ thin films were successfully synthesized by vapor deposition or conventional solution sol-gel infiltration methods. Inspection with field emission scanning electron microscopy (FE-SEM) showed that the macroporous $SiO_2$ thin films consist of interconnected air balls (~100 nm). Typical macroporous $SiO_2$ thin films showed ultralow refractive indices ranging from 1.098 to 1.138 at 633 nm, according to the infiltration conditions, which were confirmed by spectroscopy ellipsometry (SE) measurements. This research shows how the synthetic control of the macromolecule such as hydrophilic polystyrene nanopaticles and silicate sol precursors innovates the optical properties and processabilities for actual applications.

• Child Health Nursing Research
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• v.5 no.3
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• pp.241-249
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• 1999

Diaper dermatitis, or commonly called 'diaper rash', is among the most prevalent cutaneous disorders of infancy and early childhood and important issue in nursing. The term itself is not diagnostic since it encompasses a variety of acute inflammatory reactions which are best regarded as a family of disorders arising from a combination of factors specifically attributable to the use of diapers Intensive study of the rash Process has shown that skin wetness and fecal enzyme activity are damaging to skin and lead to the development of diaper rash. This suggests that it is important to keep urine away from babies' skin, so that the skin remains as dry as Possible and maintains its barrier function abilities. Controlling the urine will also minimize the mixing of urine and feces within the diaper. which helps prevent the increased activity of enzymes that attack the skin and cause irritation. Therefore, a diaper that keeps the skin drier and limits the mixing of urine and feces will help Prevent the conditions that lead to diaper rash. Since their introduction about 35 years ago, disposable baby diapers have undergone many design and performance changes. In Particular. the Performance of diapers was advanced by the introduction of absorbent gel materials (AGMs) to Provide advantages in skin care. dryness, and leakage Protection Especially, important was the introduction of AGM which increased the absorbent capacity of the diaper several fold and Yielded marked reductions in the degree of skin hydration occurring under the diaper Studies show not only drier skin but more stable skin pH and less dermatitis with AGM diapers than with home-laundered cloth diapers or single-use diapers without AGM Minimizing diaper area skin wetness is important for managing and Preventing diaper rash. To minimize wetness, parents should use super absorbent diapers.

• Bulletin of the Korean Chemical Society
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• v.25 no.1
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• pp.97-100
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• 2004

Tetragonal $K_2NiF_4$-type $La_{2-2x}Sr_{2x}Cu_{1-x}Fe_xO_{4-y}$ solid-solution have been synthesized by citrate based sol-gel method. The valence state of iron was determined by Mossbauer spectroscopy and subsequent iodometric titration clearly showed that the copper ions in this solid-solution are in the mixed valence state Cu(II/III). When x ${\geq}$ 0.3, Fe(III) is competing with the mixture of Cu(II) and Cu(III) and $La_{2-2x}Sr_{2x}Cu_{1-x}Fe_xO_{4-y}$ exhibits a metallic character. No evidence for Cu(II)-O-Fe(IV) ${\leftrightarrow}$ Cu(III)-O-Fe(III) valence degeneracy was observed. In contrast, a small amount of Fe(IV) is observed with increasing x (x = 0.4 and 0.5), revealing a semiconducting behavior. These results suggest that the electronic interaction of Cu(III)-O-Fe(III) contributes greatly to the metallic character, while the electronic interaction of Cu(II)-O-Fe(IV) deteriorates the metallic character of $La_{2-2x}Sr_{2x}Cu_{1-x}Fe_xO_{4-y}$.

• Journal of the Korean Vacuum Society
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• v.19 no.2
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• pp.96-104
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• 2010

We suggest here a cost-effective replica fabrication method for transparent and hard molds for imprinting lithography such as NIL and S-FIL. The process starts with the use of a replica hard mold from a master, using a polymer copy as a carrier. The polymer copy as a carrier was treated by soluble process for forming anti-adhesion layer. Duplicated hard molds can eliminate direct contact between a hard master and a patterned polymer on a substrate and the generated contamination of a master during the imprinting process. The replica hard mold exhibits the glass-like properties introduced here, such as transparency and hardness, make it appropriate for nanoimprint lithography and step-and-flash imprint lithography.

• The Journal of Natural Sciences
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• v.6 no.1
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• pp.103-108
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• 1993

Zeolites were discovered as a natural mineral more than two hundred ago. In the beginning, the mineral was used as ion-exchange material and adsorbent. After the end of World War II , however, a variety of zeolites have become available in large amounts because of the establishment of low temperature synthesis and the discobery of natural zeolite deposits of sedimentary origin. Various uses of xeolite were developed utilizing the unique crystal strucrure and function of these minerals. In connection with this development remakable progress has also been made in basic stuides on the related geology and mineralogy, crystallization from sols and gels, structure, ion exchange, adsorption and cataiysis. As a result, zeolites, which had been known only as mineral specimens displayed in museums. established a firm position among the high-technology masterials with excellent functional capabilities.

• Restorative Dentistry and Endodontics
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• v.45 no.2
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• pp.20.1-20.14
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• 2020

Objectives: To minimize the tooth sensitivity caused by in-office bleaching, many dentists use non-steroidal anti-inflammatory drugs and topical desensitizing gels containing potassium nitrate and sodium fluoride. This study aimed to evaluate the influence of these substances on inflammation and the expression of substance P and calcitonin gene-related peptide in pulp nerve fibers. Materials and Methods: Seventy-two rats were divided into 6 groups as follows: GI, control; GII, only dental bleaching; GIII, only ibuprofen; GIV, ibuprofen administered 30 minutes before and after the bleaching treatment and every 12 hours until the analysis; GV, only topical application of a desensitizing agent; and GVI, topical application of a desensitizing agent before dental bleaching. Placebo gel was applied to the upper left jaw and the bleaching agent was applied to the upper right jaw in all groups. Subsequently, the groups were divided into 3 subgroups based on the time of analysis: 0, 24, and 48 hours after bleaching (n = 8). The rats were euthanized and the maxillae were processed and evaluated by histopathological and immunohistochemical analyses. The data were analyzed using the Kruskal-Wallis test, followed by the Dunn test (p < 0.05). Results: In the bleaching groups, the inflammatory process and expression of neuropeptides decreased over time. The animals in which a desensitizing agent was applied showed better results within 24 hours. Conclusions: The use of a desensitizing agent had positive effects on inflammation and pain-related neuropeptide expression, minimizing the painful effects of dental bleaching treatment.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.104-107
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• 2001

The fabricated La-modified lead titanate (PLT) thin flirt without poling treatment was investigated for modulation frequency dependence of pyroelectric properties by the dynamic method. $Pb_{1-x}La_{x}Ti_{1-x/4}O_3$PLT (x=0.1) thin film having 10 mol% La content was deposited on a Pt/$TiO_{x}$/$SiO_2$/Si substrate by sol-gel method. The PLT(10) thin film exhibits a relatively excellent dielectric property. The pyroelectric coefficient (p) of the PLT(10) thin film is 6.6 x $10^{-9}$C/$\textrm{cm}^2$.K without frequency dependence. The figure of merits for the voltage responsivity and specific detectivity are 1.03${\times}$$10^{-11}$/C.cm/J and 1.46 x $10^{-9}$C.cm/J, respectively. The PLT(10) thin film has voltage responsivity ($R_{V}$) of 5.15 V/W at 8 Hz. Noise equivalent power (NEP) and specific detectivity (D＊) of the PLT(10) thin film are 9.93 x $10^{-8}$W/Hz$^{1/2}$ and 1.81 x $10^{6}$ cmHz$^{1/2}$/W at the same frequency of 100 Hz, respectively. The results means that PLT thin film having 10 mol % La content is suitable for the sensing materials of pyroelectric IR sensors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.116-119
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• 2003

Self-patterning of thin films using photosensitive sol solution has advantages such as simple manufacturing process compared to photoresist/dry etching process. In this study, ferroelectric $Sr_{0.9}Bi_{2.1}Ta_2O_9$(SBT) and $La_{0.5}Sr_{0.5}CoO_3$(LSCO)thin films have been prepared by spin coating method using photosensitive sol solution. $Sr(OC_2H5)_2$, $Bi(TMHD)_3$ and $Ta(OC_2H)_5)_5$ were used as starting materials for SBT solution and $La(OCH_2CH_2OCH_3)_3$, $Sr(OC_2H_5)_2$, $CO(OCH_2CH_2OCH_3)_2$ were used for LSCO solution. Solubility difference by UV irradiation on LSCO thin film allows to obtain a fine patterning due to M-O-M bond formation. The lowest resistivity($4{\times}10^{-3}{\Omega}cm$) of LSCO thin films was obtained by annealing at $740^{\circ}C$.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1637-1638
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• 2006

HVAC 시스템은 쾌적하고 깨끗한 운전환경을 만들어 줌으로써 운전자에게 향상된 안락성과 안전성을 제공한다. 이때 센서는 시시각각으로 변화하는 차실 내외의 환경변화에 대한 정보를 검출하여 HVAC 제어 유니트에 제공한다. 현재 HVAC 시스템에 사용되고 있는 후막 가스센서는 소자 크기와 소비전력이 크고, 제작공정이 까다로워 생산성이 낮은 단점이 있다. 이와 같은 문제점을 해결하기 위해서 최근에는 초소형화, 저소비전력, 대량생산에 의한 저가격화가 가능한 MEMS 가스센서의 연구개발이 활발히 진행되고 있다. 본 연구에서는 MEMS 구조체를 이용한 마이크로 가스센서를 설계 및 제작하였고, 감도특성을 고찰하였다. 가스 감지막은 금속산화물 페이스트를 스크린 프린팅 하는 종래의 방법 대신 MEMS 구조체에 적용 가능한 sol-gel 프로세스에 의해 형성하였다. 또 가스 감지전극과 micro-heater를 동일 평면상에 제작, 공정을 간소화하여 저가화를 시도하였다. MEMS 구조체 위에 제작된 Pt 박막 micro-heater의 인가전압에 따른 발열특성을 조사한 결과, 발열온도가 인가전압에 비례하는 이상적인 선형성을 나타내었으며, $300^{\circ}C$의 동작 온도에 도달하기 위해 65mW 이하의 저전력 동작이 가능하였다. 가스 센서의 감도특성 확인 실험은 CO 가스 10ppm, NO 가스 0.3ppm을 기준으로 수행되었으며, CO 및 NO에 대해 Rs(sensitivity, 가스반응저항/초기저항) 값은 각각 0.753 과 2.416로 우수한 성능을 나타내었다.

• Journal of Sensor Science and Technology
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• v.25 no.1
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• pp.51-56
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• 2016

This study evaluates the performance of an optical sensor and measurement system (CMA-24) which can analyze the fluctuation of dissolved oxygen and pH simultaneously. In the optical sensor system, the fluorescent materials, Rudpp and HPTS which are sensitive to dissolved oxygen and pH, respectively, are coated on the bottom of a 24-well -plate by the sol-gel technology. The detection times of the emission light of the oxygen sensor were $4,186{\pm}13.90{\mu}s$ and $4,452{\pm}36.68{\mu}s$ for the dissolved oxygen of 17% $O_2$ and 7.6% $O_2$, respectively. On the other hand, the detection times of the pH sensor were $6,699.43{\pm}14.64{\mu}s$, $6,722.24{\pm}6.21{\mu}s$, and $6,748.52{\pm}2.63{\mu}s$ using pH 6, 7, and 8, respectively. When we determined cellular respiration levels of C2C12 myocytes with CMA-24, $O_2$/pH measurement system, the ratio of the uncoupled to coupled OCR (oxygen consumption rate) was 1.41. The results mean that this CMA-24 system shows almost the same sensitiveness as the commercial system.