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Search Results: 1 - 10 of 4989 matches for " Yongdoo Choi "
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Photosensitizer-Conjugated Gold Nanorods for Enzyme-Activatable Fluorescence Imaging and Photodynamic Therapy
Boseung Jang, Yongdoo Choi
Theranostics , 2012,
Abstract: We report on the development of photosensitizer-conjugated gold nanorods (MMP2P-GNR) in which photosensitizers were conjugated onto the surface of gold nanorods (GNR) via a protease-cleavable peptide linker. We hypothesized that fluorescence and phototoxicity of the conjugated photosensitizers would be suppressed in their native state, becoming activated only after cleavage by the target protease matrix metalloprotease-2 (MMP2). Quantitative analysis of the fluorescence and singlet oxygen generation (SOG) demonstrated that the MMP2P-GNR conjugate emitted fluorescence intensity corresponding to 0.4% ± 0.01% and an SOG efficiency of 0.89% ± 1.04% compared to free pyropheophorbide-a. From the in vitro cell studies using HT1080 cells that overexpress MMP2 and BT20 cells that lack MMP2, we observed that fluorescence and SOG was mediated by the presence or absence of MMP2 in these cell lines. This novel activatable photosensitizing system may be useful for protease-mediated fluorescence imaging and subsequent photodynamic therapy for various cancers.
The development of a culturally relevant preventive intervention  [PDF]
Heeseung Choi
Open Journal of Nursing (OJN) , 2012, DOI: 10.4236/ojn.2012.22019
Abstract: Researchers often publish the numerical findings of their intervention studies while overlooking the experiential findings that could help promote more appropriate and effective interventions in the future. The present paper describes the process by which we developed a culturally relevant preventive intervention for Korean American adolescents aged 11 to 14 years and their parents. We discuss the main findings of a series of pilot studies and demonstrated how lessons learned from each study guided the development process and informed the research that followed. Program development is an iterative process that incorporates feedback from study participants. Cultural relevance is ensured when participants’ voices are reflected in the program development, implementation, and evaluation process. The final outcome of the development process was the preventive intervention improving parent-child relationships, increasing parental knowledge, enhancing parental self-efficacy, and decreasing parental stress among Korean American parents, and ultimately promoting Korean American adolescents’ mental health. The specific aims of this two-group, repeated-measures, controlled randomized study were to test the feasibility of the PRIDE (Promoting Intergenerational Dialogue about Emotional Problems) intervention and to compare its efficacy with an attention control (AC) group regarding parental knowledge, parental and filial self-efficacy, parent-child (P-C) communication, P-C conflicts, and P-C satisfaction.
How a Proactive Interventionist Can Make Strikes More Effective: Evidence from the Korean Banking Sector  [PDF]
ChungIL Choi
American Journal of Industrial and Business Management (AJIBM) , 2013, DOI: 10.4236/ajibm.2013.34051
Abstract:

This paper argues, through a case study of two industry-wide strikes in the Korean banking sector, that a proactive interventionist strike is more effective than a reactive pragmatist one in a union’s response to restructuring. Evidence from the two strikes shows that unions were able to achieve more successful outcomes from the strike in which they engaged proactively by an interventionist mode. In this case the unions identified opportunities, took the initiative and devised effective strategies that pre-empted the other parties before they had fully prepared their restructuring planning. Such a strategic capacity was gained from active organizational learning in unions derived from their previous strike failure.

The Impact of Atmospheric Phenomena on South Korean Students’ Engagement at School through the Mediating Effect of the Students’ Health  [PDF]
Shelley Choi
Atmospheric and Climate Sciences (ACS) , 2018, DOI: 10.4236/acs.2018.83020
Abstract: This study examined how South Korea’s regular significant atmospheric phenomena, the yellow dust and the monsoon, affected students’ health and academic engagement at school. Five hundred middle and high school students were surveyed to figure out the atmospheric impacts on the students’ lives. The results of this study found that the severity of yellow dust and monsoon conditions experienced by the students negatively influenced their academic engagement. However, the variable of students’ concerns about their health was shown to have a mediating effect between the intensity of yellow dust and the level of academic engagement. These results indicated the need to alleviate the yellow dust and monsoon atmospheric phenomena and their effects at both the school and national levels in order to improve the academic engagement of students in South Korea.
“Smart” Surveillance of Dusty Behavior: Illuminating the Relationship between Particulate Matter and the Atmosphere  [PDF]
Shelley Choi
Computational Water, Energy, and Environmental Engineering (CWEEE) , 2018, DOI: 10.4236/cweee.2018.73008
Abstract: Although large amounts of research have been completed to find the relationship between particulate matter and climate change, they have still proven to be inadequate. Efforts to lay the foundations for understanding atmospheric chemical reactions have been repeatedly foiled by both the size and complexity of the task, which require more than the effort of a handful of researchers. Since the development of advanced physical models for dust behavior is projected to take years, what if laypeople could dramatically expedite this process by using their mobile devices as measurement tools? With relatively little effort by many individuals, previously unknown information about the earth’s atmosphere may at last become accessible thanks to recent advances in artificial intelligence. However, there are potential obstacles. Even if all technical problems are resolved, viable plans for battling particulate matter pollution will likely need to be accompanied by environmental policies. While technological breakthroughs give reason to hope for a brighter future, the resolution of global issues requires both grassroots changes and global efforts.
A Comparative Study of Concretes Containing Crushed Limestone Sand and Natural Sand  [PDF]
Yeol Choi, Jae-Hyuk Choi
Open Journal of Civil Engineering (OJCE) , 2013, DOI: 10.4236/ojce.2013.31003
Abstract:

This paper describes the effects of high temperatures on the strength characteristic of crushed limestone sand concrete (CLSC). To compare, natural (river) sand concrete (NSC) and CLSC specimens were exposed to the three different high temperatures. Visual color-change and weight loss were also carefully examined through the tests. The test results indicated that the decreasing rate of compressive strength of CLSC after exposure to high temperature is slightly lower than that of NSC while the splitting tensile strength of CLSC indicated a very similar rate compared to NSC. Therefore, the strength variations of crushed limestone sand concrete after exposal to high temperature can be similarly treated as that of the natural sand concrete. Also it can be seen that the CLSC can use 0.5 power law equation to represent the relationship between compressive and splitting tensile strength before and after exposal to high temperature.

Examining Human Resource Competencies and Their Relationship to the Success Factors of HR Profession  [PDF]
Choi-Sang Long
Journal of Service Science and Management (JSSM) , 2008, DOI: 10.4236/jssm.2008.13029
Abstract: This study examines competencies of Human Resource (HR) professionals in the manufacturing companies of Malaysia. The Human Resource Competency Survey (HRCS) model is used in this study. The competencies that are examined in this study are business knowledge, strategic contribution, HR delivery, personal credibility and HR technology. All these competencies will be tested whether or not they are significantly related to a firm’s performance. Furthermore, researcher wanted to study the relationship of these competencies with variables such as experience, education level, firm’s size and salary of the sample. The sample employed here consists of HR professionals from Malaysian manufac-turing companies in Johor, the southernmost state of Malaysia.
A Comparison Study of Input ESD Protection Schemes Utilizing NMOS, Thyristor, and Diode Devices  [PDF]
Jin Young Choi
Communications and Network (CN) , 2010, DOI: 10.4236/cn.2010.21002
Abstract: For three fundamental input-protection schemes suitable for high-frequency CMOS ICs, which utilize protection devices such as NMOS transistors, thyristors, and diodes, we attempt an in-depth comparison on HBM ESD robustness in terms of lattice heating inside protection devices and peak voltages developed across gate oxides in input buffers, based on DC, mixed-mode transient, and AC analyses utilizing a 2-dimensional device simulator. For this purpose, we construct an equivalent circuit model of input HBM test environments for CMOS chips equipped with input ESD protection circuits, which allows mixed-mode transient simulations for various HBM test modes. By executing mixed-mode simulations including up to six active protection devices in a circuit, we attempt a detailed analysis on the problems, which can occur in real tests. In the procedure, we suggest to a recipe to ease the bipolar trigger in the protection devices and figure out that oxide failure in internal circuits is determined by the peak voltage developed in the later stage of discharge, which corresponds to the junction breakdown voltage of the NMOS structure residing in the protection devices. We explain strength and weakness of each protection scheme as an input ESD protection circuit for high-frequency ICs, and suggest valuable guidelines relating design of the protection devices and circuits.
On Certain Subclasses of Multivalent Functions Associated with a Family of Linear Operators  [PDF]
Jae Ho Choi
Advances in Pure Mathematics (APM) , 2011, DOI: 10.4236/apm.2011.14040
Abstract: Making use of a linear operator Iλp(a,c), which is defined here by means of the Hadamard product (or convolution), we introduce some new subclasses of multivalent functions and investigate various inclusion properties of these subclasses. Some radius problems are also discussed.
An Analytical Approach for Fast Automatic Sizing of Narrow-Band RF CMOS LNAs  [PDF]
Jin Young Choi
Circuits and Systems (CS) , 2012, DOI: 10.4236/cs.2012.32018
Abstract: We introduce a fast automatic sizing algorithm for a single-ended narrow-band CMOS cascode LNA adopting an inductive source degeneration based on an analytical approach without any optimization procedure. Analytical expressions for principle parameters are derived based on an ac equivalent circuit. Based on the analytical expressions and the power-constrained noise optimization criteria, the automatic sizing algorithm is developed. The algorithm is coded using Matlab, which is shown capable of providing a set of design variable values within seconds. One-time Spectre simulations assuming usage of a commercial 90 nm CMOS process are performed to confirm that the algorithm can provide the aimed first-cut design with a reasonable accuracy for the frequency ranging up to 5 GHz. This work shows one way how accurate automatic synthesis can be done in an analytical approach.
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