• Communications of the Korean Mathematical Society
• /
• v.27 no.4
• /
• pp.665-668
• /
• 2012

For a given graph G we consider a set S(G) of all symmetric matrices A = [$a_{ij}$] whose nonzero entries are placed according to the location of the edges of the graph, i.e., for $i{\neq}j$, $a_{ij}{\neq}0$ if and only if vertex $i$ is adjacent to vertex $j$. The minimum rank mr(G) of the graph G is defined to be the smallest rank of a matrix in S(G). In general the computation of mr(G) is complicated, and so is that of the maximum multiplicity MaxMult(G) of an eigenvalue of a matrix in S(G) which is equal to $n$ - mr(G) where n is the number of vertices in G. However, for trees T, there is a recursive formula to compute MaxMult(T). In this note we show that this recursive formula for MaxMult(T) also computes the path cover number $p$(T) of the tree T. This gives an alternative proof of the interesting result, MaxMult(T) = $p$(T).

• 전기의세계
• /
• v.19 no.3
• /
• pp.10-17
• /
• 1970

The main focus of this paper is the analysis on the controlling characteristics of self-excited D.C. motor driven by thyristor chopper. The controlling characteristics of short shunt compound motor driven by poly phase multiple thyristor chopper is better than that of driven by single phase thyristor chopper. And we got the following conclusions. A. Motor current capacity could be increased by the multiplicity n increase. B. Speed-torque characteristics is linear and adquate for constant Horsepower motor. C. Maximum current Riple ratio is proportional to almost inverse m$^{2}$. Also here shows the stable conditions and semiconducterlize datas for controlling the self-excited D.C. motor driven by thyristor chopper.

• Journal of Oral Medicine and Pain
• /
• v.26 no.2
• /
• pp.133-146
• /
• 2001

This study was performed to predict the conservative treatment outcome of TMD patients by investigating the prognostic factors ; symptom duration, history of previous treatment, history of previous medication, history of trauma, disability of daily activity, severity of pain, noise, limitation of mouth opening(LOM) and maximum comfortable opening(MCO). Two hundreds and fifty-four subjects were selected for this study among the TMD patients who had visited the Dept. of Oral Medicine BNUH and been treated conservatively with medication, physical therapy, behavioral treatment, and splint therapy from 1991 to 2000. The subjects were divided into two groups improved or unimproved according to the treatment response following six months of conservative treatment. Those who showed less than 1 on NAS for pain, TMJ noise, and opening limitation belonged to the improved group and those who showed more than 2 on NAS belonged to the unimproved group. The two groups were compared with respect to symptom severity, number of diagnosis, history of trauma, previous treatment, previous medication, and disability of daily activity. A prognostic equation with the factors revealed to be significantly related to the prognosis of conservative treatment was obtained. The obtained results were as follows ; 1. In improved group, mean duration of history was 12 months, mean treatment duration of a patient was 4 months an mean number of treatment was about 10 times. In other words, in unimproved group, mean duration of history was 27.4 months, mean treatment duration of patient was 10.5 months and mean number of treatment was 19 times. 2. In unimproved group, multiple diagnosis, chronicity, disability of daily activity were significantly greater than that of the improved group. 3. Patients in unimproved group revealed severe noise at first visit and smaller maximum comfortable opening comparatively. 4. Prognostic factors such as duration of treatment, number of treatment, multiplicity, and chronicity and disability of daily activity showed a significant relation in prediction of improvement. 5. Prognostic equation with significant variables is as follows ; Y = 1.984 - 0.251Noise + 0.068MCO - 0.673Multiplicity. - 0.958Chronicity - 0.065Disability. Classification accuracy of 70.3 %, sensitivity of 71.4% and specificity of 66.7% were shown. 6. Prognostic equation with all factors is as follows : Y = 1.599 - 0.038Pain - 0.256Noise - 0.006Limitation + 0.068MCO - 0.580Multiplicity - 1.025Chronicity - 0.720Disability - 0.329Medication - 0.087Treatment + 0.740Trauma. Classification accuracy of 70.3 %, sensitivity of 73% and specificity of 64.3% were shown. 7. Prognostic value of the improved group with significant factors was $1.0446{\pm}1.0726$ and prognostic value of the unimproved group with significant factors was $-0.013{\pm}1.0146$. Prognostic value of the improved group with all factors was $1.0465{\pm}1.0849$ and prognostic value of the unimproved group with all factors was $-0.057{\pm}1.0611$.

• Journal of Microbiology and Biotechnology
• /
• v.17 no.5
• /
• pp.739-744
• /
• 2007

Insect cell lines and the control of infection for obtaining the maximum amount of polyhedrin-Cry1Ac-polyhedrin fusion protein from Bactrus in monolayer and suspension culture systems were tested. Growth rates of the Trichoplusia ni(High-Five) cell line in both culture systems were better than the other insect cell lines, Spodoptera frugiferda(Sf-9, Sf-21), Trichoplusia ni(Tn5), and Spodoptera exigua(Se301). The expression of the fusion protein in a monolayer culture showed that Se301 cells were 2.3-4.8 times more productive on a per cell basis than the other cell lines. However, in suspension culture, only High-Five cells were productive. High-Five cells infected with Bactrus at a multiplicity of infection(MOI) of 5 and a cell density of $3.0{\times}10^5$ cells per ml were more productive than the other infection condition in a suspension culture suitable for a large-scale production of baculovirus. In conclusion, for the large-scale production of Bactrus in vitro, High-Five cells showing good growth and high productivity are suitable.

• Korean Journal of Radiology
• /
• v.24 no.1
• /
• pp.39-50
• /
• 2023

Objective: To assess the contrast-enhanced CT and ultrasonography (US) findings of intracholecystic papillary neoplasm (ICPN) and determine the imaging features predicting ICPN associated with invasive carcinoma (ICPN-IC). Materials and Methods: In this retrospective study, we enrolled 119 consecutive patients, including 60 male and 59 female, with a mean age ± standard deviation of 63.3 ± 12.1 years, who had pathologically confirmed ICPN (low-grade dysplasia [DP] = 34, high-grade DP = 35, IC = 50) and underwent preoperative CT or US. Two radiologists independently assessed the CT and US findings, focusing on wall and polypoid lesion characteristics. The likelihood of ICPN-IC was graded on a 5-point scale. Univariable and multivariable logistic regression analyses were performed to identify significant predictors of ICPN-IC separately for wall and polypoid lesion findings. The performances of CT and US in distinguishing ICPN-IC from ICPN with DP (ICPN-DP) was evaluated using the area under the receiver operating characteristic curve (AUC). Results: For wall characteristics, the maximum wall thickness (adjusted odds ratio [aOR] = 1.4; 95% confidence interval [CI]: 1.1-1.9) and mucosal discontinuity (aOR = 5.6; 95% CI: 1.3-23.4) on CT were independently associated with ICPN-IC. Among 119 ICPNs, 110 (92.4%) showed polypoid lesions. Regarding polypoid lesion findings, multiplicity (aOR = 4.0; 95% CI: 1.6-10.4), lesion base wall thickening (aOR = 6.0; 95% CI: 2.3-15.8) on CT, and polyp size (aOR = 1.1; 95% CI: 1.0-1.2) on US were independently associated with ICPN-IC. CT showed a higher diagnostic performance than US in predicting ICPN-IC (AUC = 0.793 vs. 0.676; p = 0.002). Conclusion: ICPN showed polypoid lesions and/or wall thickening on CT or US. A thick wall, multiplicity, presence of wall thickening in the polypoid lesion base, and large polyp size are imaging findings independently associated with invasive cancer and may be useful for differentiating ICPN-IC from ICPN-DP.

• Korean Journal of Mathematics
• /
• v.20 no.4
• /
• pp.395-402
• /
• 2012

A digraph D is primitive if there is a positive integer $k$ such that there is a walk of length $k$ between arbitrary two vertices of D. The exponent of a primitive digraph is the least such $k$. Wielandt graph $W_n$ of order $n$ is known as the digraph whose exponent is $n^2-2n+2$, which is the maximum of all the exponents of the primitive digraphs of order n. It is known that the diameter of the multiple direct product of a digraph $W_n$ strictly increases according to the multiplicity of the product. And it stops when it attains to the exponent of $W_n$. In this paper, we find the diameter of the direct product of Wielandt graphs.

• Journal of KIISE:Software and Applications
• /
• v.27 no.7
• /
• pp.769-783
• /
• 2000

In this paper, in order to disambiguate Korean noun word sense, we define a local context and explain how to extract it from a raw corpus. Following the intuition that two different nouns are likely to have similar meanings if they occur in the same local context, we use, as a clue, the word that occurs in the same local context where the target noun occurs. This method increases the usability of extracted knowledge and makes it possible to disambiguate the sense of infrequent words. And we can overcome the data sparseness problem by extending the verbs in a local context. The sense of a target noun is decided by the maximum similarity to the clues learned previously. The similarity between two words is computed by their concept distance in the sense hierarchy borrowed from WordNet. By reducing the multiplicity of clues gradually in the process of computing maximum similarity, we can speed up for next time calculation. When a target noun has more than two local contexts, we assign a weight according to the type of each local context to implement the differences according to the strength of semantic restriction of local contexts. As another knowledge source, we get a co-occurrence information from dictionary definitions and example sentences about the target noun. This is used to support local contexts and helps to select the most appropriate sense of the target noun. Through experiments using the proposed method, we discovered that the applicability of local contexts is very high and the co-occurrence information can supplement the local context for the precision. In spite of the high multiplicity of the target nouns used in our experiments, we can achieve higher performance (89.8%) than the supervised methods which use a sense-tagged corpus.

• Journal of Microbiology and Biotechnology
• /
• v.8 no.1
• /
• pp.8-13
• /
• 1998

Animal cells in culture typically convert most of the glucose they consume into lactate. The accumulation of lactate, however, is commonly cited as one of the factors that inhibit cell growth and limit the maximum cell concentration that can be achieved in culture. The specific production of lactate and the amount of glucose converted to lactate can be reduced when cells are grown in a fed-batch culture in which the residual glucose concentration is maintained at low levels. Such a fed-batch culture was used to grow and adapt hybridoma cells into a low-lactate-producing state before changing into continuous culture. The cells reached and maintained a high viable cell concentration at steady state. In a similar manner, cells that were initially grown in batch culture and a glucose-rich environment reached a steady state with a cell concentration that is much lower. The feed composition and dilution rates for both cultures were similar, suggesting steady state multiplicity. From a processing perspective the desired steady state among those is the one with the least metabolite production. At such seady state nutrient concentration in the feed can be further increased to increase cell and product concentrations without causing the metabolite inhibitory effect typically seen in a cell culture. Controlling cell metabolism in a continuous culture to reduce or eliminate waste metabolite production may significantly improve the productivity of mammalian cell culture processes.

• KSBB Journal
• /
• v.10 no.3
• /
• pp.292-297
• /
• 1995

Studies on the production of Newcastle disease virus(NDV) were carried out to optimize culture conditions such as initial pH, temperature, serum concentration, multiplicity of infection(M.O.I.) as well as the addition of polycation, antioxidant, and DMSO. Initial pH from 7.2 to 8.1 showed little difference on NDV production but the initial pH below 6.8 resulted in the negative effect. The highest NDV titer was obtained at 0.1 M.O.I. In addition, the maximum production of virus was achieved at 2% FBS and optimum temperature was found to be $34^{\circ}C$. Treatment of polycoation increased the virus production. When ascorbic acid was added as an antioxidant, NDV production was also enhanced. Utilization of DMSO, a well-known permeabilizing agent, showed an inhibitory effect on the propagation of NDV.

• Korean Chemical Engineering Research
• /
• v.58 no.2
• /
• pp.184-189
• /
• 2020

Van de Vusse reactors show the maximum points in input-output steady state maps and dramatic changes in their dynamic characteristics around those maximum points. According to their operating regions, there appear sign changes in steady state gains and nonlinear characteristics such as non-minimum phase dynamics which cause difficulties in applying controllers. Many nonlinear controllers that are available and newly designed are applied to these Van de Vusse reactor processes and their performances are tested. Reactor examples with real reactions have been reported. However, due to difficulties in constructing and operating chemical reactor systems, they are not adequate to be used for real applications of control experiments and hence most of results are based on simulations studies. Here, we propose a liquid level system that realizes most of the steady state and dynamic characteristics of Van de Vusse reactor, and two nonlinear control methods that can be used as base methods to compare nonlinear controllers newly designed. Liquid level experimental system and two nonlinear control methods are very simple and can be used to test performances of nonlinear controllers in practice.