• Archives of Pharmacal Research
• /
• v.25 no.5
• /
• pp.718-723
• /
• 2002

CKD-602 (7-[2-(N-isopropylamino)ethyl]-(20S)-camptothecin) is a recently-developed synthetic camptothecin analogue and currently under clinical development by Chong Kun Dang Pharm (Seoul, Korea). CKD-602 showed potent topoisomerase inhibitory activity in vitro and broad antitumor activity against various human tumor cells in vitro and in vivo in animal models. This study describes the pharmacodynamics of the immediate and delayed cytotoxicity induced by CKD-602 in a human colorectal adenocarcinoma cell line, HT-29, and its intracellular drug accumulation by HPLC. The present study was designed to address whether the higher activity of CKD-602 with prolonged exposure is due to delayed exhibition of cytotoxicity and/or an accumulation of anti proliferative effect on continuous drug exposure. The drug uptake study was performed to determine whether the delayed cytotoxicity is due to a slow drug accumulation in cells. CKD-602 produced a cytotoxicity that was exhibited immediately after treatment (immediate effect) and after treatment had been terminated (delayed effect). Both the immediate and delayed effects of CKD-602 showed a time dependent decrease in 4IC_{50}$ values. Drug uptake was biphasic and the second equilibrium level was obtained as early as at 24hr, indicating that the cumulative and delayed antitumor effects of CKD-602 were not due to slow drug uptake. On the other hand, CKD-602 treatment was sufficient to induce delayed cytotoxicity after 4hr, however, longer treatment (＞24hr) enhanced its cytotoxicity due to the intracellular accumulation of the drug, which requires 24hr to reach maximum equilibrium concentration. In addition, $C^n$$\times$T=h analysis (n=0.481) indicated that increased exposure times may contribute more to the overall antitumor activity of CKD-602 than drug concentration. Additional studies to determine the details of the intracellular uptake kinetics (e.g., concentration dependency and retention studies) are needed in order to identify the optimal treatment schedules for the successful clinical development of CKD-602.

• Korea journal of population studies
• /
• v.21 no.1
• /
• pp.162-183
• /
• 1998

This study examines the sampling bias that may have resulted from the large number of missing observations. Despite well-designed and reliable sampling procedures, the observed sample values in DSFH(Demographic Survey on Changes in Family and Household Structure, Japan) included many missing observations. The head administerd survey method of DSFH resulted in a large number of missing observations regarding characteristics of elderly non-head parents and their children. In addition, the response probability of a particular item in DSFH significantly differs by characteristics of elderly parents and their children. Furthermore, missing observations of many items occurred simultaneously. This complex pattern of missing observations critically limits the ability to produce an unbiased analysis. First, the large number of missing observations is likely to cause a misleading estimate of the standard error. Even worse, the possible dependency of missing observations on their latent values is likely to produce biased estimates of covariates. Two models are employed to solve the possible inference biases. First, EM algorithm is used to infer the missing values based on the knowledge of the association between the observed values and other covariates. Second, a selection model was employed given the suspicion that the probability of missing observations of proximity depends on its unobserved outcome.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.9
• /
• pp.39-47
• /
• 2012

The opinion of user on a certain product is expressed in positive/negative sentiments for specific features of it. In some cases, they are expressed for a holistic part of homogeneous specific features, or expressed for product itself. Therefore, in the area of opinion mining, name of opinion features to be extracted are specific feature names, holonyms for theses specific features, and product names. However, when the opinion target is described with product name or holonym, sometimes it may not match feature name of opinion sentence to true opinion target intended by the reviewer. In this paper, we present a method to extract opinion targets from opinion sentences. Most importantly, we propose a method to extract true target from the feature names mismatched to a intended target. First, we extract candidate opinion pairs using dependency relation between words, and then select feature names frequently mismatched to opinion target. Each selected opinion feature name is replaced to a specific feature intended by the reviewer. Finally, in order to extract relevant opinion features from the whole candidate opinion pairs including modified opinion feature names, candidate opinion pairs are rearranged by the order of user's interest.

• Journal of muscle and joint health
• /
• v.7 no.2
• /
• pp.241-257
• /
• 2000

Rheumatoid arthritis as one of the chronic illness requiring management in long period of time puts great burden to patients, their family and society. For patients with chronic illnesses, providing a social support is important and the most important source comes from spouses. Therefore we assessed burden of husbands of female rheumatoid arthritic patients and also found out the factors affecting burden. The sample of study was 107 female rheumatoid arthritic patients and their spouses. The tool of assessing spouses' burden was the revised version of subjective and objective parameters developed by Montgomery et al.(1985). The results are as follows: 1. General characteristics of patients and spouses: The mean age of the patients was 48 years. Educational level of patients was high school 41.1%. The mean age of the spouses was 51years. Educational level of spouses was mostly high school(40.2%) and college(29.9%) graduate. The mean marital period was 23.4years. Average income per month was 1,609,000 won. The average duration since diagnosis was 9.4years. As a therapy, 67.3% chose standard drug therapy. Average rating of discomfort by patient was 3.05(range 1-5) and that of severity was 3.48 and that of dependency was 2.58. The husband's rating of their spouses disease severity was 3.68. 2. Husbands' burden: The average burden in subjective items was 21.61(range 6-36) and objective items was 35.24(range 10-60). The average of total burden was 56.59(range 16-96). 3. Husband's total burden correlated with patient's age, educational level of patients, therapy method, patient's level of discomfort, patient's severity, patient's level of dependence, husband's recognition of level of severity in statistical level. Husband's objective burden correlated with patient's age, educational level of patient, patient's level of discomfort, husband's recognition of level of severity. Husband's subjective burden correlated with patient's age, educational level of patients, therapy method, patient's severity, patient's level of dependence, husband's recognition of level of severity. 4. Linear correlation analysis on burden: The husbands' total burden is explained in 37 7% by husband's recognition of level of severity and husband's age. The husbands' objective burden is explained in 31.2% by patient's level of dependence, husband's age, husband's recognition of level of severity. The husbands' subjective burden is explained in 26.7% by husband's recognition of level of severity and patient's age. In conclusion, husbands' level of burden is affected by many factors and therefore nursing strategy for relieving burden of middle aged husbands should be individualized taking these factors into consideration.

• Korean Journal of Materials Research
• /
• v.11 no.5
• /
• pp.339-344
• /
• 2001

An all solid-state thin film supercapacitor (TFSC) with Co$_3$O$_4$/LiPON/Co$_3$O$_4$ structure was fabricated on Pt/Ti/Si substrate using Co$_3$O$_4$ thin film electrode. Each Co$_3$O$_4$ film was grown by reactive dc reactive magnetron sputtering with increasing $O_2$/[Ar+O$_2$] ratio. Amorphous LiPON electrolyte film was deposited on Co$_3$O$_4$/Pt/Ti/Si in pure nitrogen ambient by using reactive rf magnetron sputtering. The electrochemical behavior of the Co$_3$O$_4$/LiPON/Co$_3$O$_4$ multi-layer structures exhibits a behavior of a bulk-type supercapacitor, even though much lower capacity (from 5 to 25 mF/$\textrm{cm}^2$-$\mu\textrm{m}$) than that of the bulk one. It was found that the TFSC showed a fairly constant discharge capacity with a constant current of 50 $\mu\textrm{A}/\textrm{cm}^2$ at the cut-off voltage 0-2V during 400 cycles. It is shown that the electrochemical behavior of the Co$_3$O$_4$/LiPON/Co$_3$O$_4$ TFSC is dependent upon the sputtering gas ratio. The capacity dependency of electrode films on different gas ratios was explained by different structural, electrical, and surfacical properties.

• The Korean Journal of Quaternary Research
• /
• v.5 no.1
• /
• pp.15-31
• /
• 1991

A total of 90 surface sediment samples, collected from the continental margin area bordering east and southeast coast of Korea, were subject to the geochemical analyses with the aim of filling the gap in our knowledge of this environment. The analyzed items included the major elements (Al, Fe, Mg, Ca, K, Na, p and Mn), organic carbon, and some trace metals (Ba, Co, Cu, Sr and Zn). The sediment grain-size exerted a predominant influence on the contents of most elements, with the exceptions of Ca, K, Sr and Ba. The Ca and Sr contents, being closely interrelated each other, were mainly controlled by the calcium carbonate content. The K content, on the other hand, appeared to be influenced by both illite and feldspar. The Ba content showed a certain relationship with that of K, suggesting a common source of these two elements; potassium feldspar. The R-mode factor analysis result also reaffirmed the above-mentioned controlling factors on the sediment geochemistry. The grain-size dependency of trace metals obscures their areal distribution pattern from the total contents. However, with the metal/aluminum ratios we could differentiate the subtle difference in the metal enrichment. Hence, sediments of the southern coastal area appear to receive some anthropogenic inputs of metals, though the effect is still negligible.

• Journal of the Korean Data and Information Science Society
• /
• v.27 no.4
• /
• pp.935-946
• /
• 2016

In this paper, we analyzed wage determinants of the vocational high school graduates utilizing both individual-level and work region-level variables. We formulate the models in the way wage determination has multi-level structure in the sense that individual wage is influenced by individual-level variables (level-1) and work region-level (level-2) variables. To incorporate dependency between individual wages into the model, we utilize hierarchical linear model (HLM). The major results are as follows. First, it is shown that the HLM model is better than the OLS regression models which do not take level-1 and level-2 variables simultaneously into account. Second, random effects on sex, maester dummy and engineering dummy variables are statistically significant. Third, the fixed effects on business hours and mean wage of regular job for level-2 variables are statistically significant effect individual-level wages. Finally, parental education level, parental income, number of licenses and high school grade are statistically significant for higher individual-level wages.

• The Korean Journal of Air & Space Law and Policy
• /
• v.23 no.2
• /
• pp.93-114
• /
• 2008

The purpose of this study is to review the changes in the aviation safety management system, how that system has evolved and what forces caused these changes to take place. Also included is an examination of the development process of the aviation safety management system in view of the new institutionalism, identifying the patterns of change. Based on the results of this study, I propose policy methods to design a desirable civil aviation safety system with a view toward raising the safety standards in the Korean civil aviation community. The major analysis variables are as follows: first, aviation accidents caused by external factors and international standards as independent variables second, environmental changes and political processes affecting aviation safety management system as major mediating variables and third, the aviation safety management legal system, the aviation safety management organizations and an expert participation system as dependent variables. The institutional changes and continuance of the aviation safety management system show that when specific circumstances arise, the continuance lasts depending on the path dependency, and in a certain circumstance, when immanent changing factors reach a critical point, the system suddenly changes by a punctuated equilibrium, which are all included in this study.

• The KIPS Transactions:PartB
• /
• v.11B no.5
• /
• pp.603-610
• /
• 2004

The distributed Information Retrieval System centrally controlled by mediator or meta search engine result in congestion of heavy traffic and int he problem of increment of cost for the reason of the design of complicated algorithm for central control and installation of hardware. So to figure out this problem, the way is needed that has independent retrieval functionality and can cooperate each other without dependency. In this paper, we overview a few works involved in distributed information retrieval system, then, implement algorithm and design the frame-work of distributed information retrieval system using sequential transferring method(STM) including multiple information retrieval system separated from central control. For this first of all, we present a web partition policy which devide and manage web logically and we present the sequential query processing way by means of illustration through changing numbered information retrieval system. Then, we also present 3-layered structure of framework and function and module of each layer suitable for information retrieval system. Last of ail, for effective implementation of STM algorithm we analysis module structure and present description of pseudocode of this, and show that the proposed STM algorithm works smoothly by demonstration of sequential query transfer process between servers.

• Journal of the Korean Chemical Society
• /
• v.33 no.1
• /
• pp.37-45
• /
• 1989

Voltammetric behavior of alkylammonium ion was studied in the absence and in the presence of crown ether in propylene carbonate as solvent. The peak potentials and the peak currents, their dependency on the concentrations, the reversibility of the electrode reactions are described. In the presence of crown ether chemical reaction might be preceeded before the electron-transfer process, the peak potential for the reduction shifts at the negative direction as the concentration of crown ether to the electrolyte solution increases. The addition of crown ether(20mM 18CR6)to the electrolyte solution made it possible to determine voltammetrically the dialkylammonium ions($Me_2NH^{+}_{2};O.6{\sim}0.8mM$) in the presence of the monoalkylammonium ions ($EtNH^{+}_{3} ;1.6mM$) and the monoalkylammonium ions ($EtNH^{+}_{3} ; 0.5{\sim}2.5mM$) in the presence of the dialkylammonium ions($Me_2NH^{+}_{2};0.5mM$)