• 대한수학회지
• /
• 제41권4호
• /
• pp.773-773
• /
• 2004

In our paper "Paranormal contractions and invariant subspaces" published in Journal of the Korean Mathematical Society, Volume 40 (2003), Number 6, pp.933-942, the statement to observation (1) on page 935 should read:(omitted)

• The Korean Journal of Ceramics
• /
• 제2권1호
• /
• pp.1-10
• /
• 1996

Transparent conducting $SnO_2$-based thin films have been coated on float substrates such as fused quartz, and ceramic fiber cloths such as the Nexel and E-glass cloth from tin alkoxides by the sol-gel technique. Also, thin films of alternating layers of $SnO_2$ and $SiO_2$ have been fabricated by dip coating. The sheet resistance and average visible transmittance of the films were investigated in the aspect of the applications as transparent electrodes such as liquid crystal displays, photo-detectors and solar cells. The Nextel and E-glass cloths coated with antimony-doped tin oxide (ATO) had sheet resistance of as low as $20 \;ohm/{\Box}$ and $120ohm/\;{\Box}$, respectively. The promotion effects of additives as $La_2O_3$ and Pt on the ethanol gas sensing properties of the films were investigated in the aspects of the applications as an alcohol sensor and a breath alcohol checker. Possible evidence of quantum well effects in the oxide multilayers of $SnO_2$ and $SiO_2$ was investigated.

• Interaction and multiscale mechanics
• /
• 제1권2호
• /
• pp.191-209
• /
• 2008

In this paper, we model grain boundary evolution based on a multiple level set method. Grain boundary migration under a curvature-induced driving force is considered and the level set method is employed to deal with the resulting topological changes of grain structures. The complexity of using a level set method for modeling grain structure evolution is due to its N-phase nature and the associated geometry compatibility constraint. We employ a multiple level set method with a predictor-multicorrectors approach to reduce the gaps in the triple junctions down to the grid resolution level. A ghost cell approach for imposing periodic boundary conditions is introduced without solving a constrained problem with a Lagrange multiplier method or a penalty method. Numerical results for both uniform and random grain structures evolution are presented and the results are compared with the solutions based on a front tracking approach (Chen and Kotta et al. 2004b).

• Interaction and multiscale mechanics
• /
• 제4권3호
• /
• pp.219-237
• /
• 2011

Recent advances in scientific computing enable the full atomistic simulation of DNA molecules. However, there exists length and time scale limitations in molecular dynamics (MD) simulation for large DNA molecules. In this work, a two-level homogenization of DNA molecules is proposed. A wavelet projection method is first introduced to form a coarse-grained DNA molecule represented with superatoms. The coarsened MD model offers a simplified molecular structure for the continuum description of DNA molecules. The coarsened DNA molecular structure is then homogenized into a three-dimensional beam with embedded molecular properties. The methods to determine the elasticity constants in the continuum model are also presented. The proposed continuum model is adopted for the study of mechanical behavior of DNA loop.

• 한국세라믹학회지
• /
• 제40권7호
• /
• pp.625-631
• /
• 2003

Recent work at USC has focused on strategies to enhance the toughness and overall mechanical performance of polymer foams for use in lightweight sandwich structures. Both mechanical and chemical approaches have been employed with reasonable success. Fiber reinforcement, though difficult from a processing perspective, can lead to substantial enhancements in toughness and strength, while reducing friability. Chemical modifications are also challenging from a processing perspective, but can produce similar enhancements in performance. Efforts to enhance performance of phenolic foam and PVC foam through fiber reinforcement and chemical modification are described, along with the resulting enhancements in performance.

• 대한수학회보
• /
• 제42권1호
• /
• pp.169-177
• /
• 2005

A Hilbert Space operator T is of class Q if $T^2{\ast}T^2-2T{\ast}T + I$ is nonnegative. Every paranormal operator is of class Q, but class-Q operators are not necessarily normaloid. It is shown that if a class-Q contraction T has no nontrivial invariant subspace, then it is a proper contraction. Moreover, the nonnegative operator Q = $T^2{\ast}T^2-2T{\ast}T + I$ also is a proper contraction.

• Journal of Korean Neurosurgical Society
• /
• 제40권4호
• /
• pp.217-226
• /
• 2006

Malignant gliomas are the most common type of primary brain tumor and are in great need of novel therapeutic approaches. Advances in treatment have been very modest, significant improvement in survival has been lacking for many decades, and prognosis remains dismal. Despite "gross total" surgical resections and currently available radio-chemotherapy, malignant gliomas inevitably recur due to reservoirs of notoriously invasive tumor cells that infiltrate adjacent and non-adjacent areas of normal brain parenchyma. In principle, the immune system is uniquely qualified to recognize and target these infiltrative pockets of tumors cells, which have generally eluded conventional treatment approaches, In the span of the last 10 years, our understanding of the cancer-immune system relationship has increased exponentially; and yet we are only beginning to tease apart the intricacies of the central nervous system and immune cell interactions. This article reviews the complex associations of the immune system with brain tumors. We provide an overview of currently available treatment options for malignant gliomas, existing gaps in our knowledge of brain tumor immunology, and strategies that might be exploited for improved design of "custom immunotherapeutics." We will also examine major new immunotherapy approaches that are being actively investigated to treat patients with malignant glioma, and identify some current and future research priorities in this area.

• Investigative Magnetic Resonance Imaging
• /
• 제21권4호
• /
• pp.210-222
• /
• 2017

Purpose: To develop a novel combination of controlled aliasing in parallel imaging results in higher acceleration (CAIPIRINHA) with integrated SSFP (CAIPI-iSSFP) for accelerated SSFP imaging without banding artifacts at 3T. Materials and Methods: CAIPI-iSSFP was developed by adding a dephasing gradient to the balanced SSFP (bSSFP) pulse sequence with a gradient area that results in $2{\pi}$ dephasing across a single pixel. Extended phase graph (EPG) simulations were performed to show the signal behaviors of iSSFP, bSSFP, and RF-spoiled gradient echo (SPGR) sequences. In vivo experiments were performed for brain and abdominal imaging at 3T with simultaneous multi-slice (SMS) acceleration factors of 2, 3 and 4 with CAIPI-iSSFP and CAIPI-bSSFP. The image quality was evaluated by measuring the relative contrast-to-noise ratio (CNR) and by qualitatively assessing banding artifact removal in the brain. Results: Banding artifacts were removed using CAIPI-iSSFP compared to CAIPI-bSSFP up to an SMS factor of 4 and 3 on brain and liver imaging, respectively. The relative CNRs between gray and white matter were on average 18% lower in CAIPI-iSSFP compared to that of CAIPI-bSSFP. Conclusion: This study demonstrated that CAIPI-iSSFP provides up to a factor of four acceleration, while minimizing the banding artifacts with up to a 20% decrease in the relative CNR.

• 한국물환경학회지
• /
• 제20권5호
• /
• pp.415-421
• /
• 2004

Litter wastes on highway runoff are gradually being considered one of the major pollutants of concern in protecting the integrity of receiving waters for beneficial use. The California State Water Resources Control Board has identified in their 303(d) list at least 36 water bodies where trash or litter is considered a pollutant of concern. The first TMDL adopted by the Region 4 (Los Angeles area) of the California State Water Quality Control Board was for trash in the Los Angeles River. The first flush characteristic study was developed to obtain first flush water quality and litter data from representative stormwater runoff from standard highway drainage outfalls in the Los Angeles area. Total captured gross pollutants in stormwater runoff were monitored at six Southern California highway sites over two years. The gross pollutants were 90% vegetation and 10% litter. Approximately 50% of the litter was composed of biodegradable materials. The event mean concentrations show an increasing trend with antecedent dry days and a decreasing trend with total runoff volume or total rainfall. Event mean concentrations were ranged 0.0021 to 0.259g/L for wet gross pollutants and 0.0001 to 0.027g/L for wet litters. The first flush phenomenon was evaluated and the impacts of various parameters such as rainfall intensity, drainage area, peak flow rate, and antecedent dry period on litter volume and loading rates were evaluated. First flush phenomenon was generally observed for litter concentrations, but was not apparent with litter mass loading rates. Litter volume and loading rates appear to be directly related to peak storm intensity, antecedent dry days and total flow volume.

• 해양환경안전학회지
• /
• 제16권2호
• /
• pp.223-228
• /
• 2010

전 세계적으로 기후변화에 대응하기 위한 노력이 본격화되는 가운데, 그동안 관심이 적었던 항만으로부터의 탄소배출량이 상당량에 이르고 이의 억제를 위한 노력이 LA/LB(Los Angeles/Long Beach)항만을 중심으로 선진항만에서 전개되고 있다. 우리나라는 최근 Green Port 전략의 일환으로 부산항에서 저탄소 항만운영정책이 강화되고 있다. 저탄소 항만운영은 단기적으로 항만비용을 증가시켜 가격경쟁력을 약화시킨다. 따라서 부산항의 경우 저탄소 항만운영으로 인한 비용을 항만이용자에게 부담시키지 않고 항만당국이 저탄소를 위한 정책을 시행하고 비용을 부담하고 있다. 반면 LA/LB의 경우 저탄소 항만운영의 비용을 선주 및 화주 등 항만이용자에게 부담시키고 있다. 본 연구에서는 부산항과 LA/LB항의 저탄소 항만운영에 관한 비교분석을 통해 부산항의 지속가능한 항만운영의 시사점을 제시하였다.