• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2445-2448
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• 2007

Self-assembled monolayers (SAMs) were formed by adsorption of thioacetyl-terminated tolanethioacetate (TTA) on Au(111) in a 0.5-mM ethanol solution after one day immersion at room temperature. Molecular-scale STM imaging revealed that the TTA SAMs were composed of two mixed phases; an ordered phase with small domains describing a ( × 2 )R30° structure and a disordered phase. Interestingly, after annealing the precovered TTA SAMs on Au(111) at 90 °C for 1 h, the small ordered domains grew unidirectionally, resulting in the formation of unique rod-like domains, which were assigned a ( × 2 )R7° structure. These results will be very useful in understanding the formation and thermal behavior of TTA SAMs on gold surfaces.

• Advances in concrete construction
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• 제17권3호
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• pp.159-165
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• 2024

The interaction of short range zigzag single walled carbon nanotubes CNTs based on modified elasticity model is studied in this paper. The numerical accurate results are presented. Through this model the vibrational frequency of zigzag (5, 0), (12, 0) single-walled CNTs with certain end conditions are estimated. The natural frequencies of single walled carbon nanotubes are obtained by elasticity model. It is considered for various estimation of height-to-diameter ratio of zigzag tube. This simulation is performed to quantify small scale effects. Moreover, the natural frequencies increase by increasing the height-to-diameter ratio. These frequencies are very sensitive with low height-to-diameter ratio. The feasibility and effective use of present model is explained by comparison of outputs of earlier investigations.

• 과학교육연구지
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• 제38권2호
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• pp.302-316
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• 2014

본 연구는 6학년 1학기 산과 염기 단원 중 5차시를 Small-Scale Chemistry를 적용한 실험 수업 프로그램으로 개발하였다. 개발한 프로그램 적용을 경남 창원시에 소재한 Y초등학교 6학년 3개반은 SSC를 활용한 과학수업(n=86)을, 3개 반은 전통적인 실험 수업(n=87)을 진행한 후 학생들의 과학 학업성취도와 과학 학업성취도에 미치는 영향을 알아보았다. 개발한 수업 프로그램을 학생들에게 적용하기에 앞서, 중간학력평가 과학 학업성취도 점수에 대한 t검증을 통해 실험집단과 비교집단 간의 동질성을 확인하였고 실험집단은 2인 1조 또는 개별로, 비교집단은 6명 1모둠으로 구성하여 5차시에 걸쳐 수업을 진행하였다. 그 결과 t-검증을 통한 과학 학업성취도에서 유의확률 0.034로 유의수준 0.05에서 실험집단과 비교집단 사이에 유의미한 차이가 있었다. 추가적으로 전통적인 실험을 한 1개 반과 2명 1조 SSC 적용 실험 수업을 한 1개 반, 개별 SSC 적용 실험 수업을 한 1개 반의 과학 학업성취도를 살펴보았다. 일원배치 분산분석을 통해 살펴 본 결과 F 통계값 3.759, 유의확률 0.027로 유의수준 0.05에서 유의미한 차이가 있었으며, 전통적인 실험반의 평균은 67.58, 2인 1조 SSC 적용 실험반은 75.86, 개별 SSC 적용 실험반은 80.89로 개별 SSC 적용 실험반에서 과학 학업성취도가 가장 높았다. 또한 SSC를 적용한 실험 수업 프로그램을 준비할 때 교사는 수업 준비 및 수업 시간에 대한 부담이 줄었으며, 수업시간 동안 학생활동을 적극적으로 도와 줄 수 있었을 뿐 아니라 학생들의 실험활동도 적극적으로 이루어졌다. 이러한 결과를 통해 SSC 적용 실험 수업 프로그램 개발은 의미가 있으며 기존의 전통적인 실험 방법보다 학생들의 과학 학업성취도를 향상시킬 수 있음을 제시하였다.

• 천문학회보
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• 제35권1호
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• pp.25-25
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• 2010

The spectroscopy over a region from 3 to 17 ${\mu}m$ based on the tuneable diode lasers (TDLAS) is the most powerful technique for in situ studies of the diagnostics of small molecules. The increasing interest in small molecules especially containing carbon, oxygen, hydrogen, and fluorine containing ones can be fulfilled by TDLAS at 0.0001 cm-1 resolution, because most of these compounds are infrared active. TDLAS provides a means of determining the absolute concentrations of the ground states of stable and transient molecular species, which can be employed for the time dependent studies in sub micro second scale. Information about gas temperature and population densities can also be derived from TDLAS measurements. Collisional energy transfer between the small molecules can be studied with TDLAS. Also, a variety of free radicals and molecular ions have been detected by TDLAS. Since plasmas with molecular feed gases are used in many applications, there are new applications in industrial field. Recently, the development of quantum cascade lasers (QCLs) offers an attractive new option for TDLAS.

• 유기물자원화
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• 제11권1호
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• pp.149-153
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• 2003

본 연구는 소규모의 축사에서 발생하는 축분을 합리적으로 처리하기 위해 소규모 정체식 퇴비화의 적용 가능성을 검토하였다. 이 때 미생물을 첨가하여 퇴비화에 미치는 영향을 조사하였다. 처리구는 무처리의 대조구, 일반 Bacteria와 Lactobacillus을 처리한 BL구, BL구에 Photo.를 첨가한 BLP구 등 3개를 두었으며, 별도의 퇴비화 장치 없이 퇴적시킨 후 간헐적인 뒤집기를 실시하였다. 원료의 수분함량은 60% 정도였으며, 우분, 왕겨, 톱밥이 혼합되었다. 퇴비화 과정 중 온도는 3일 이내에 $60^{\circ}C$이상 상승하였으며, BLP와 BL구에서 Control구에 비해 초기 온도상승에 우세하였다. 원료의 초기 pH가 높아 퇴비화 과정중 pH 변화는 모든 처리구에서 크지 않았으며, 약알카리성에 머물렀다. EC는 뇨와 분의 계속적인 배출로 축적되어 초기에 높은 값을 보였으며, 퇴비화 과정중 5~10%의 상승을 보였다. C/N율의 감소는 BLP구에서 가장 높은 22.7%를 보였으며, BL과 Control구에서는 각각 19.2와 17.5%의 감소를 보였다. 식물독성평가에서는 BLP가 가장 짧은 시간에 안정되었으며, BL구와 Control구의 차이는 없었다. 소규모 축사농가에서 발생하는 축분의 처리는 적절한 뒤집기와 수분함량을 갖춘 소규모 정체식 퇴비화에 의해 가능하며, 미생물의 첨가는 초기 온도상승과 식물독성물질의 감소에 긍정적이었으나, 부숙도에 큰 영향은 미치지 못하였다.

• Bulletin of the Korean Chemical Society
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• 제26권9호
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• pp.1369-1380
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• 2005

The reaction of methyl radical with iodine molecule on an attractive potential energy surface is studied by classical trajectory procedures. The reaction occurs over a wide range of impact parameters with the majority of reactive events occurring in the backward rebound region on a subpicosecond scale. A small fraction of reactive events take place in the forward hemisphere on a longer time scale. The ensemble average of reaction times is 0.36 ps. The occurrence of reactive events is strongly favored when the incident radical and the target molecule align in the neighborhood of collinear geometry. Since the rotational velocity of I2 is slow, the preferential occurrence of reactive events at the collinear configuration of $CH_3{\ldots}I{\ldots}$I leads to the reaction exhibiting an anisotropic dependence on the orientation of $I_2$. During the collision, there is a rapid flow of energy from the $H_3C{\ldots}$I interaction to the I-I bond. The $CH_3I$ translation and $H_3C$-I vibration share nearly all the energy released in the reaction, and the distribution of the vibrational energy is statistical. The reaction probability is $\cong$0.4 at the $CH_3$ and I2 temperatures maintained at 1000 K and 300 K, respectively. The probability is weakly dependent on the $CH_3\;and\;I_2$ temperatures between 300 K and 1500 K.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.198-198
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• 2011

Organocatalysis is a relatively new and popular area within the field of chiral molecule synthesis. It is one of the main branches of enantioselective synthesis with enzymatic and organometallic catalysis. In recent years, immense high quality studies on catalysis by chiral secondary amines were reported. These progresses instantly led to different organocatalytic activation concepts, so thousands of researchers from academia and the chemical industry are currently involved in this field and new ideas, new approaches, and creative thinking have been rapidly emerged. Organocatalysts, some of which are natural products, appear to solve the problems of metal catalysts. Compared to metal-based catalysis, they have many advantages including savings in cost, time, and energy, easier experimental procedure, and reduction of chemical waste. These benefits originate from the following factors. First, organocatalysts are generally stable in oxygen and water in the atmosphere, there is no need for special equipments or experimental techniques to operate under anhydrous or anaerobic conditions. Second, organic reagents are naturally available from biological materials as single enantiomers that they are easy and cheap to prepare which makes them suitable for small-scale to industrial-scale reactions. Third, in terms of safety related catalysis, small organic molecules are non-toxic and environmentally friendly. Therefore, the purpose of this research is to develop novel synthetic methods and design for various organocatalyst. Furthermore, it is expected that these organocatalysts can be applied to a variety of asymmetric reactions and study the transition state of these reactions using a metal sulface. Here, we report the synthesis of unprecedented organocatalysts, proline and pyrrolidine derivatives with quaternary carbon center.

• Bulletin of the Korean Chemical Society
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• 제34권1호
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• pp.139-142
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• 2013

A study was carried out to evaluate the solid phase micro-extraction (SPME) for formaldehyde emission analysis of uncoated plywood. In SPME, formaldehyde was on-fiber derivatized through headspace extraction and analyzed by gas chromatography coupled with mass spectrometry (GC/MS). The SPME was compared with desiccators (DC-JAS 233), small-scale chamber (SSC-ASTM D6007) and liquid-liquid extraction (LLE-EPA 556) methods which were performed in accordance with their respective standards. Compared to SSC (RSD 4.3%) and LLE (RSD 5.0%), the SPME method showed better repeatability (RSD 1.8%) and not much difference from DC (RSD 1.4%). The SPME has proven to be highly precise (at 95% confidence level) with better recovery (REC 102%). Validation of the SPME method for formaldehyde quantitative analysis was evidenced. In addition, the SPME by air sampling directly from plywood specimens (SPME-W) correlated best with DC ($r^2$ = 0.983), followed by LLE ($r^2$ = 0.950) and SSC ($r^2$ = 0.935).

• 한국환경과학회:학술대회논문집
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• 한국환경과학회 2003년도 International Symposium on Clean Environment
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• pp.151-154
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• 2003

With estmating drinking water demands of Ulsan city, the amount would be increased from 523,000ton/day in 2006 to 635,000 ton/day in 2016. Also, the dependence of Nakdong River on the Ulsan city as a source of drinking water will be very high up to 54.4％ of total drinking water demands. Small-scale drinking water dam is no economical because of excessive construction cost and long construction period. However, development of riverbed and ground water of existing rivers is more economical than that of small-scale drinking water dam. In this study, to utilized Dongchun River as a drinking water resource, Modflow model was used to predict the amount of riverbed and ground water of Dongchun River basin. As a result, available amount of riverbed water was assumed in 6,000 ton/day by worst case (when perfect dry stream) and in case of ground water, it was assumed in 17,800 ton/day.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.102-102
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• 2016

Water, which is most abundant in Earth surface and very closely related to all forms of living organisms, has a simple molecular structure but exhibits very unique physical and chemical properties. Even though tremendous effort has been paid to understand this nature's core substance, there amazingly still lefts much room for scientist to explore its novel behaviors. Especially, as the scale goes down to nano-regime, water shows extraordinary properties that are not observable in bulk state. One of such interesting features is the formation of nanoscale bubbles showing unusual long-term stability. Nanobubbles can be spontaneously formed in water on hydrophobic surface or by decompression of gas-saturated liquid. In addition, the nanobubbles can be generated during electrochemical reaction at normal hydrogen electrode (NHE), which possibly distorts the standard reduction potential at NHE as the surface nanobubble screens the reaction with electrolyte solution. However, the real-time evolution of these nanobubbles has been hardly studied owing to the lack of proper imaging tools in liquid phase at nanoscale. Here we demonstrate, for the first time, that the behaviors of nanobubbles can be visualized by in situ transmission electron microscope (TEM), utilizing graphene as liquid cell membrane. The results indicate that there is a critical radius that determines the long-term stability of nanobubbles. In addition, we find two different pathways of nanobubble growth: i) Ostwald ripening of large and small nanobubbles and ii) coalescence of similar-sized nanobubbles. We also observe that the nucleation and growth of nanoparticles and the self-assembly of biomolecules are catalyzed at the nanobubble interface. Our finding is expected to provide a deeper insight to understand unusual chemical, biological and environmental phenomena where nanoscale gas-state is involved.