• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.533-534
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• 2012

Colloidal III-V semiconductor nanocrystal quantum dots (NQDs) have attracted attention as they can be applied in various areas such as LED, solar cell, biological imaging, and so on because they have decreased ionic lattices, lager exciton diameter, and reduced toxicity compared with II-VI compounds. However, the study and application of III-V semiconductor nanocrystals is limited by difficulties in control nucleation because the molecular bonds in III-V semiconductors are highly covalent compared to II-VI compounds. There is a need for a method that provides rapid and scalable production of highly quality nanoparticles. We present a new synthetic scheme for the preparation of InP nanocrystal quantum dots using new phosphorus precursor, P(SiMe2tbu)3. InP nanocrystals from 530nm to 600nm have been synthesized via the reaction of In(Ac)3 and new phosphorus precursor in noncoordinating solvent, ODE. This opens the way for the large-scale production of high quality Cd-free nanocrystal quantum dots.

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.51-51
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• 2012

There is a growing interest in innovative chemical synthesis in microreactors owing to high efficiency, selectivity, and yield. In microfluidic systems, the low-volume spatial and temporal control of reactants and products offers a novel method for chemical manipulation and product generation. Glass, silicon, poly(dimethylsiloxane) (PDMS), and plastics have been used for the fabrication of miniaturized devices. However, these materials are not the best due to either of low chemical durability or expensive fabrication costs. In our group, we have recently addressed the demand for economical resistant materials that can be used for easy fabrication of microfluidic systems with reliable durability. We have suggested the use of various specialty polymers such as silicon-based inorganic polymers and fluoropolymer, flexible polyimide (PI) films that have not been used for microfluidic devices, although they have been used for other areas. And inexpensive lithography techniques were used to fabricate Lab-on-a-Chip type of microreactors with differently devised microchannel design. These microreactors were demonstrated for various synthetic reactions: liquid, liquid-gas organic chemical reactions in heterogeneous catalytic processes, syntheses of polymer and non-trivial inorganic materials. The microreactors were inert, and withstand even harsh conditions, including hydrothermal reaction. In addition, various built-in microstructures inside the microchannels, for example Pd decorated peptide nanowires, definitely enhance the uniqueness and performance of microreactors. These user-friendly Lab-on-a-Chip devices are useful alternatives for chemist and chemical engineer to conventional chemical tools such as glass.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.614-614
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• 2013

The effect of graphene growth parameters on the number of graphene layers were systematically studied and growth mechanism on copper substrate was proposed. Parameters that could affect the thickness of graphene growth include the pressure in the system, gas flow rate, growth pressure, growth temperature, and cooling rate. We hypothesis that the partial pressure of both the carbon sources and hydrogen gas in the growth process, which is set by the total pressure and the mole fraction of the feedstock, could be the factor that controls the thickness of the graphene. A synthetic method to produce such large area graphene films with precise thickness from mono- to few-layer would be ideal for chemists and physicists to explore the promising electronic applications of these materials. Here, large-area uniform mono-, bi-, and few-layer graphene films were successfully synthesized on copper surface in selective growth windows, with a finely tuned total pressure and $CH_4$/$H_{2gas}$ ratio. Our findings may facilitate both the large-area synthesis of well-controlled graphene features and wide range of applications of graphene.

• Journal of Power System Engineering
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• v.9 no.3
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• pp.71-78
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• 2005

A high-pressure hose includes rebar layers of the synthetic fiber such as nylon or a steel wire to control internal pressure. The hose assembly is manufactured through the swaging process to clamp the hose into the metal fittings. Usually, the hose behavior is affected by the resultant of the longitudinal and circumferential forces produced by the internal pressure. The rebar layers can appear the most ideal rebar effect when they are arranged to the same direction as the resultant force. The braid angle applied in the rebar layers is an important factor in determining ultimate burst pressure and overall hose life. Failure can occur on the contacted parts of a hose with the metal fittings under severe operating conditions such as high pressure and temperature of the inner fluid. In this paper, the mechanical behavior between the hose and the metal fittings during the swaging process and the stress variation characteristics of a high-pressure hose under a constant applied pressure are analyzed with respect to the braid angle of steel wire using the finite element method.

• Nano
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• v.13 no.11
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• pp.1850136.1-1850136.12
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• 2018

Three-dimensional (3D) mixed phases NiSe nanoparticles growing on the nickel foam were synthesized via a simple one-step hydrothermal method. A series of experiments were carried out to control the morphology by adjusting the amount of selenium in the synthetic reaction. Meanwhile, the as-prepared novel column-acicular structure NiSe exist three advantages including ideal electrical conductivity, high specific capacity and high cycling stability. It delivered a high capacitance of $10.8F\;cm^{-2}$ at a current density- of $5mA\;cm^{-2}$. An electrochemical capacitor device operating at 1.6 V was then constructed using NiSe/NF and activated carbon (AC) as positive and negative electrodes. Moreover, the device showed high energy density of $31W\;h\;kg^{-1}$ at a power density of $0.81kW\;kg^{-1}$, as well as good cycling stability (77% retention after 1500 cycles).

• Journal of Animal Reproduction and Biotechnology
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• v.35 no.2
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• pp.142-148
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• 2020

The research work was undertaken to determine an effective fertilization medium, sperm separation method and sperm capacitating agent for optimum in vitro fertilization (IVF) rates of indigenous zebu cow oocytes. In experiment 1, tissue culture medium (TCM 199), Tyrode's albumin lactate pyruvate (TALP) and Brackett and Oliphant (BO) medium were used as basic medium for IVF of oocytes of indigenous zebu cows. In experiment 2, three sperm separation methods namely centrifugation, swim up and percoll gradient methods were used for separation of motile and viable spermatozoa for IVF. In experiment 3, for capacitation of spermatozoa, IVF medium supplemented with the heparin, mixture of penicillamine, hypotaurine and epinephrine (PHE) or the combination of heparin with PHE were used for fertilization. In vitro culture (IVC) of presumptive zygotes was done in modified synthetic oviduct fluid (mSOF) medium using standard procedure 24 h after sperm-oocytes co-culture. The cleavage rate was determined to evaluate the efficacy of fertilization medium, sperm separation method and sperm capacitating agent 24 h after IVC. The cleavage rate was higher in oocytes fertilized in TALP (63.3%) than in TCM 199 (47.5%) (p < 0.05). The cleavage rate was higher in oocytes fertilized by spermatozoa separated by percoll gradient method (62.3%) than by centrifugation (51.6%) (p < 0.05). The cleavage rate of oocytes was higher when insemination was done with spermatozoa capacitated in TALP supplemented with heparin and PHE (61.3%) compared to control (40.9%) (p < 0.05). In conclusions, TALP based medium and percoll gradient sperm separation followed by capacitation with combination of heparin and PHE are suitable for IVF of indigenous zebu cow oocytes in Bangladesh.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.383-388
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• 2005

Depth recovery in robot vision is an essential problem to infer the three dimensional geometry of scenes from a sequence of the two dimensional images. In the past, many studies have been proposed for the depth estimation such as stereopsis, motion parallax and blurring phenomena. Among cues for depth estimation, depth from lens translation is based on shape from motion by using feature points. This approach is derived from the correspondence of feature points detected in images and performs the depth estimation that uses information on the motion of feature points. The approaches using motion vectors suffer from the occlusion or missing part problem, and the image blur is ignored in the feature point detection. This paper presents a novel approach to the defocus technique based depth from lens translation using sequential SVD factorization. Solving such the problems requires modeling of mutual relationship between the light and optics until reaching the image plane. For this mutuality, we first discuss the optical properties of a camera system, because the image blur varies according to camera parameter settings. The camera system accounts for the camera model integrating a thin lens based camera model to explain the light and optical properties and a perspective projection camera model to explain the depth from lens translation. Then, depth from lens translation is proposed to use the feature points detected in edges of the image blur. The feature points contain the depth information derived from an amount of blur of width. The shape and motion can be estimated from the motion of feature points. This method uses the sequential SVD factorization to represent the orthogonal matrices that are singular value decomposition. Some experiments have been performed with a sequence of real and synthetic images comparing the presented method with the depth from lens translation. Experimental results have demonstrated the validity and shown the applicability of the proposed method to the depth estimation.

• Analytical Science and Technology
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• v.32 no.2
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• pp.56-64
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• 2019

Recently, a number of adulterated products, which are advertised as hair-growth enhancer have been emerged among those who suffer hair loss disease. For continuous control of illegal products, in this study, a rapid and sensitive method for simultaneous screening of 12 compounds that enhance hair-growth was established to protect public health by ultrahigh-performance liquid chromatography coupled to quadrupole-orbitrap mass spectrometry (UHPLC-Q-Orbitrap-MS). Fragmentation pathways of them were proposed based on $MS^2$ spectral data obtained using the established method. In this analysis, the LODs and LOQs ranged from 0.05 to 50 ng/mL and from 0.17 to 167 ng/mL, respectively. The square of the linear correlation coefficient ($R^2$) was determined as more than 0.995. The intra- and inter-assay accuracies were respective 88-112 % and 88-115 %. Their precision values were measured within 5 % (intra-day) and 10 % (inter-day). Mean recoveries of target compounds in adulterated products ranged from 84 to 115%. The relative standard deviation of stability was less than 12 % at $4^{\circ}C$ for 48 h. The method was employed to screen 14 dietary supplements advertised to be effective for the treatment of hair loss. Some of the products (~21 %) were proven to contain synthetic drugs that promote hair growth such as triaminodil, minoxidil, and finasteride.

• Korean Journal of Animal Reproduction
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• v.7 no.2
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• pp.72-85
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• 1983

This presentation firstly is discussed the characteristics of estrus, the time of first postpartum estrus, and the relative accurate of various estrus detection aids and secondly discussed the abnormalities of estrus and ovarian function and its control by treatment of exogenous hormones in cattle and pig. Longer estrus cycles as well as the shorter than 18 day cycles showed the lowered conception rates as compared to the normal cycles of 18 to 25 days. Other characteristics of est겨s such as duration of estrus, intensity of estrus and time of estrus are reviewed to affect fertility. The first postpartum ovulation and estrus in cows usually occurs about 20 to 30 days and 40 to 50 days after parturition, respectively. Irregularities in estrus cycle length have been conducted during early postpartum period. In sows, weaning is followed by ovulation and estrus although there is some individual variation. The most common method of estrus detection is direct visual observation on standing estrus behavior, but various aids of estrus detection have been empolyed with varying degree of effectiveness. The results from heat detector devices are about as accurate as twice-daily observation(about 90%). The abnormal estrus can be classified into three types; irregular or continuous estrus, silent estrus and anestrus. Cystic ovarian disease, follicular cysts and luteal cysts, is a serious cause of reproductive failure in cattle and pig. The follicular cysts are much more common than luteal cysts and the incidence of ovarian cysts in dairy cattle is higher than beef cattle and pig. The occurrences of ovarian cysts have been closely associated with levels of milk production, stages of postpartum period, nutritional levels and seasons. The luteal cysts and persistent corpora lutea are responsive to the luteolytic effects of the recently synthetic analogues of PGF2$\alpha$ in cows and sows and recently GnRH or LH-RH has been successfully used as a treatment for cows and sows with ovarian follicular cysts.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.5
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• pp.1207-1212
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• 2015

In this paper, we propose three-dimensional (3D) visualization and recognition techniques of micro-objects under photon-starved conditions using photon counting integral imaging microscopy. To capture high resolution 2D images with different perspectives in the proposed method, we use Synthetic Aperture Integral Imaging (SAII). Poisson distribution which is mathematical model of photon counting imaging system is used to extract photons from the images. To estimate 3D images with 2D photon counting images, the statistical estimation is used. Therefore, 3D images can be obtained and visualized without any damage under photon-starved conditions. In addition, 3D object recognition can be implemented using nonlinear correlation filters. To prove the usefulness of our technique, we implemented the optical experiment.