• Journal for History of Mathematics
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• v.18 no.4
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• pp.113-124
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• 2005

For a Tychonoff space X, C(X) is a Riesz-space. It is well known that C(X) is order-Cauchy complete if and only if X is a quasi~F space and that if X is a compact space and QF(X) is a minimal quasi-F cover of X, then the order- Cauchy completion of C(X) is isomorphic to C(QF(X)). In this paper, we investigate motivations and historical backgrounds of the definition for quasi-spaces and the construction for minimal quasi-F covers.

• Journal of Sericultural and Entomological Science
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• v.30 no.1
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• pp.33-39
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• 1988

In the case of white cocoon, the fluorescence colors are classified as a yellowish fluorescence cocoon(Y.F.C.) and a violet fluorescence cocoon(V.F.C.) by exposing to ultra-violet ray. Accordingly, experiments were carried out to investigate the difference of sericin behaviors between Y.F.C. and V.F.C. by measuring the sericin solubility, surface tension and viscosity of the sericin solution. Also, the reelability of two different type of cocoons was investigated in the silk reeling process. The results were summarized as follows; 1. The sericin solubility of Y.F.C. shell is higher than that of V.F.C. shell with the dissolution temperature and time. It is shown that the sericin solubility curves of Y.F.c. and V.F.C. are similar in shape, but the difference of sericin solubility between Y.F.C. and V.F.C. is more significant at higher bath temperature. 2. The initial sericin dissolution curves of Y.F.C. and V.F.C. cocoon shell can be divided by four parts within the range of dissolving time from 5 minutes to 60 minutes. The initial dissolution velocity of Y.F.C. shell is faster than that of V.F.C. but the velocity difference is negligible after 30 minutes of dissolving time. 3. The gelation of V.F.C. sericin solution is faster than that of Y.F.C. at early stage(in the range of 15 minutes to 60 minutes). 4. In the silk reeling process, the reelability of Y.F.C. is better than that of V.F.C. with about 11%. This is mainly due to the higher sericin solubility in Y.F.C. followed by the fast dissolution velocity.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.254-259
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• 2021

Optical and electrical characteristics of the fluorocarbon films deposited in a high-density C4F8 plasma under various source powers and pressures were investigated. The F/C ratio of the fluorocarbon film deposited in a high-density C4F8 plasma increased with increasing source power and decreasing pressure due to two-step deposition mechanism. The change in the F/C ratio of the film directly affected the optical and electrical characteristics of the fluorocarbon films deposited in a high-density C4F8 plasma. The refractive index of the fluorocarbon film increased with decreasing source power and increasing pressure contrary to the dependence of the film's F/C ratio on the source power and pressure. This was because the increase in the F/C ratio suppressed electronic polarization and weakened the network structures of the film. The resistivity of the fluorocarbon film showed the same behavior as its F/C ratio. In other words, the resistivity increased with increasing source power and decreasing pressure, resulting from stronger repellence of electrons at higher F/C ratios. This work offers the feasibility of the use of the fluorocarbon films deposited in a high-density C4F8 plasma as an alternative to low dielectric constant materials because the optical and electrical properties of the fluorocarbon film can be directly controlled by its F/C ratio.

• Bulletin of the Korean Mathematical Society
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• v.58 no.4
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• pp.915-937
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• 2021

In this paper we deal with the open problem posed by Lü, Li and Yang [10]. In fact, we prove the following result: Let f(z) be a transcendental meromorphic function of finite order having finitely many poles, c₁, c₂, …, c_n ∈ ℂ\{0} and k, n ∈ ℕ. Suppose fⁿ(z), f(z+c₁)f(z+c₂) ⋯ f(z+c_n) share 0 CM and fⁿ(z)-Q₁(z), (f(z+c₁)f(z+c₂) ⋯ f(z+c_n))^(k) - Q₂(z) share (0, 1), where Q₁(z) and Q₂(z) are non-zero polynomials. If n ≥ k+1, then $(f(z+c_1)f(z+c_2)\;{\cdots}\;f(z+c_n))^{(k)}\;{\equiv}\;{\frac{Q_2(z)}{Q_1(z)}}f^n(z)$. Furthermore, if Q₁(z) ≡ Q₂(z), then $f(z)=c\;e^{\frac{\lambda}{n}z}$, where c, λ ∈ ℂ \ {0} such that e^{λ(c₁+c₂+⋯+c_n)} = 1 and λ^k = 1. Also we exhibit some examples to show that the conditions of our result are the best possible.

• Journal of the Korean Vacuum Society
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• v.7 no.4
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• pp.368-373
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• 1998

As device dimensions approach submicrometer size in ULSI, the demand for interlayer dielectric materials with very low dielectric constant is increased to solve problems of RC delay caused by increase in parasitic resistance and capacitance in multilevel interconnectins. Fluorinated amorphous carbon in one of the promising materials in ULSI for the interlayer dielectric films with low dielectric constant. However, poor thermal stability and adhesion with Si substrates have inhibited its use. Recently, amorphous hydrogenated carbon (a-C:H) film as a buffer layer between the Si substrate and a-C:F has been introduced because it improves the adhesion with Si substrate. In this study, therfore, a-C:F/a-C:H films were deposited on p-type Si(100) by ECRCVD from $C_2F_6, CH_4$and $H_2$gas source and investigated the effect of forward power and composition on the thickness, chemical bonding state, dielectric constant, surface morphology and roughness of a-C:F films as an interlayer dielectric for ULSI. SEM, FT-IR, XPS, C-V meter and AFM were used for determination of each properties. The dielectric constant in the a-C:F/a-C:H films were found to decrease with increasing fluorine content. However, the dielectric constant increased after furnace annealing in $N_2$atomosphere at $400^{\circ}C$ for 1hour due to decreasing of flurorine content. However, the dielectric constant increased after furnace annealing in $N_2$atmosphere at $400^{\circ}C$ for 1hour due to decreasing of fluorine concentration.

• Composites Research
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• v.32 no.3
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• pp.148-157
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• 2019

In this study, $C_f/SiC$, $SiC_f/SiC$ and $C_f-SiC_f/SiC$ ceramic composites reinforcing carbon fiber, SiC fiber and hybrid fiber were fabricated by hybrid TGCVI and PIP process. After the thermal shock cycle, 3-point bending and Oxy-Acetylene torch test, their mechanical behavior, oxidation and erosion resistance were evaluated. The $C_f/SiC$ composite showed a decrease in mechanical property along with increasing temperature, a pseudo-ductile fracture mode and a large quantity of erosion. The $SiC_f/SiC$ composite exhibited stronger mechanical property and lower erosion rate compared to the $C_f/SiC$, but brittle fracture mode. On the other hand, hybrid type of $C_f-SiC_f/SiC$ composite gave the best mechanical property, more ductile failure mode than the $SiC_f/SiC$, and lower erosion rate than the $C_f/SiC$. During the Oxy-Acetylene torch test, the $SiO_2$ formed by reaction of the SiC matrix with oxygen prevented further oxidation or erosion of the fibers for $C_f-SiC_f/SiC$ and $SiC_f/SiC$ composites particularly. In conclusion, if a hybrid composite with low porosity is prepared, this material is expected to have high applicability as a high temperature thermo-structural composite under high temperature oxidation atmosphere by improving low mechanical property due to the oxidation of $C_f/SiC$ and brittle fracture mode of $SiC_f/SiC$ composite.

• Communications of the Korean Mathematical Society
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• v.24 no.1
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• pp.127-144
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• 2009

Let f be a diffeomorphism of a compact $C^{\infty}$ manifold, and let p be a hyperbolic periodic point of f. In this paper we introduce the notion of $C^1$-stable inverse shadowing for a closed f-invariant set, and prove that (i) the chain recurrent set $\cal{R}(f)$ of f has $C^1$-stable inverse shadowing property if and only if f satisfies both Axiom A and no-cycle condition, (ii) $C^1$-generically, the chain component $C_f(p)$ of f associated to p is hyperbolic if and only if $C_f(p)$ has the $C^1$-stable inverse shadowing property.

• Bulletin of the Korean Mathematical Society
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• v.57 no.5
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• pp.1307-1317
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• 2020

Let f be a nonconstant meromorphic function of hyper order strictly less than 1, and let c be a nonzero finite complex number such that f(z + c) ≢ f(z). We prove that if ∆_cf = f(z + c) - f(z) and f share 0, ∞ CM and 1 IM, then ∆_cf = f. Our result generalizes and greatly improves the related results.

• The Journal of Information Technology
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• v.1 no.2
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• pp.15-24
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• 1998

C.I.F. and F.O.B. contracts are the chief terms used in international trade contracts. But, in recently, the multimodal transport which is based on the containerization and the improvement of air transport has been grown gradually, Regardless of theese change in international trade environment, most of the contract of sale is made by C.I.F. and F.O.B. contracts which are based on the traditional port to port transport. In other words, there are some limitation in terms of legal base in which traditional C.I.F. and F.O.B. contract is applied to the changed environment. Especially, problems arised in marine insurance which export by F.O.B. trade terms. Therefore, when the parties of the contracts of sale make an sale contracts by using the container ship and Multimodal Transport, they should use the F.C.A. and C.I.P. contracts Instead of F.O.B. and C.I.F. contracts for the transport of goods. And parties of the contracts of sale need to gain a better understanding of the characteristic of F.C.A. and C.I.P. terms and the problem of the F.C.A. and C.I.P. contracts used in the performance on international multimodal transport.

• Korean Journal of Optics and Photonics
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• v.6 no.3
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• pp.201-213
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• 1995

By the use of computer simulation including collisional mixing kinetic processes of the B- and C-state in the upper laser level the output characteristics of electron-beam pumped XeF$(C\rightarrowA$ excimer laser are analyzed. We compared the results between experiments and simulations for the $XeF^*(C)$ formation that correlated the number of densities of the $XeF^*(B)$. We obtained good agreement$(28.5 mJ\pm5%)$ with comparisons between experiment and simulation and confirmed the optimal gas mixing ratio of $Xe/F_2/Ar=5.26/0.49/94.28%$ at atmospheric pressure laser medium under the condition of 70 ns [FWHM] electron-beam (800 kV, 21 kA). Also through the simulation we have investigated that the $XeF^*(C)$ formation channel, the $XeF^*(C)$ relaxation channel, and the absorption channel of bluegreen wavelength region as a function of F2 halogen donor and Xe partial pressure. ssure.