• Title/Summary/Keyword: model change

Search Result 10,978, Processing Time 0.048 seconds

Determinants of Mobile Application Use: A Study Focused on the Correlation between Application Categories (모바일 앱 사용에 영향을 미치는 요인에 관한 연구: 앱 카테고리 간 상관관계를 중심으로)

  • Park, Sangkyu;Lee, Dongwon
    • Journal of Intelligence and Information Systems
    • /
    • v.22 no.4
    • /
    • pp.157-176
    • /
    • 2016
  • For a long time, mobile phone had a sole function of communication. Recently however, abrupt innovations in technology allowed extension of the sphere in mobile phone activities. Development of technology enabled realization of almost computer-like environment even on a very small device. Such advancement yielded several forms of new high-tech devices such as smartphone and tablet PC, which quickly proliferated. Simultaneously with the diffusion of the mobile devices, mobile applications for those devices also prospered and soon became deeply penetrated in consumers' daily lives. Numerous mobile applications have been released in app stores yielding trillions of cumulative downloads. However, a big majority of the applications are disregarded from consumers. Even after the applications are purchased, they do not survive long in consumers' mobile devices and are soon abandoned. Nevertheless, it is imperative for both app developers and app-store operators to understand consumer behaviors and to develop marketing strategies aiming to make sustainable business by first increasing sales of mobile applications and by also designing surviving strategy for applications. Therefore, this research analyzes consumers' mobile application usage behavior in a frame of substitution/supplementary of application categories and several explanatory variables. Considering that consumers of mobile devices use multiple apps simultaneously, this research adopts multivariate probit models to explain mobile application usage behavior and to derive correlation between categories of applications for observing substitution/supplementary of application use. The research adopts several explanatory variables including sociodemographic data, user experiences of purchased applications that reflect future purchasing behavior of paid applications as well as consumer attitudes toward marketing efforts, variables representing consumer attitudes toward rating of the app and those representing consumer attitudes toward app-store promotion efforts (i.e., top developer badge and editor's choice badge). Results of this study can be explained in hedonic and utilitarian framework. Consumers who use hedonic applications, such as those of game and entertainment-related, are of young age with low education level. However, consumers who are old and have received higher education level prefer utilitarian application category such as life, information etc. There are disputable arguments over whether the users of SNS are hedonic or utilitarian. In our results, consumers who are younger and those with higher education level prefer using SNS category applications, which is in a middle of utilitarian and hedonic results. Also, applications that are directly related to tangible assets, such as banking, stock and mobile shopping, are only negatively related to experience of purchasing of paid app, meaning that consumers who put weights on tangible assets do not prefer buying paid application. Regarding categories, most correlations among categories are significantly positive. This is because someone who spend more time on mobile devices tends to use more applications. Game and entertainment category shows significant and positive correlation; however, there exists significantly negative correlation between game and information, as well as game and e-commerce categories of applications. Meanwhile, categories of game and SNS as well as game and finance have shown no significant correlations. This result clearly shows that mobile application usage behavior is quite clearly distinguishable - that the purpose of using mobile devices are polarized into utilitarian and hedonic purpose. This research proves several arguments that can only be explained by second-hand real data, not by survey data, and offers behavioral explanations of mobile application usage in consumers' perspectives. This research also shows substitution/supplementary patterns of consumer application usage, which then explain consumers' mobile application usage behaviors. However, this research has limitations in some points. Classification of categories itself is disputable, for classification is diverged among several studies. Therefore, there is a possibility of change in results depending on the classification. Lastly, although the data are collected in an individual application level, we reduce its observation into an individual level. Further research will be done to resolve these limitations.

Release Strategy for the Red Fox (Vulpes vulpes) Restoration Project in Korea Based on Population Viability Analysis (개체군 생존력 분석을 이용한 여우복원사업 방사전략)

  • Lee, Hwa-Jin;Lee, Bae-Keun;Kwon, Gu-Hui;Chung, Chul-Un
    • Korean Journal of Environment and Ecology
    • /
    • v.27 no.4
    • /
    • pp.417-428
    • /
    • 2013
  • The red fox (Vulpes vulpes), listed as a Class I endangered species by the Ministry of Environment of Korea, has been considered to be extinct in South Korea since the 1980s, and an intensive restoration project has been underway in Sobaeksan national park. This study was carried out to develop a suitable model for the red fox reintroduction program based on Population viability analysis (PVA) by using the VORTEX program. If 10 animals (5 females and 5 males) were continuously released into the initial zero population every year for 10 years, population growth rate and extinction probability over the next 50 years after the introduction of the population were $0.018{\pm}0.204$ and 0.354, respectively; the maximum population size was 116.34 at the 16th year after the first release, and a reduction rate of 1.22 every year from the 17th year was inferred. We found that additional releases would be needed from the 17th year after the initial release to maintain a positive growth rate and to prevent the extinction of the released red foxes, and releasing more than 12 individuals every year would be needed for the long-term, continuous existence of red foxes. By contrast, if fewer than 6 red fox individuals were released the extinction probability over the next 50 years was more than 80%. To maintain the minimum population growth rate, the release of more than 8 individuals were needed for positive population growth. The population growth rate was more stable when 10 animals in the change of their sex rate every year from the set value were released as the female-to- male sex ratio of 6:4 rather than 1:1. However, if the female-biased sex ratio was increased by more than 7:3, a negative population growth was expected. The occurrence rate of roadkill and poaching are important factors in the red fox restoration project. The extinction probability was decreased to 30% if each factor was decreased to 3% based on the standard baseline; however, if each factor was increased to more than 3%, an extinction rate of about 90% was reached over the next 50 years.

Oral Health and Related Factors for the Elderly (Structural Equation Modeling을 통한 노인(老人)의 구강건강(口腔健康) 관련요인(關聯要因) 분석(分析))

  • Seung, Jeung-Hee
    • Journal of dental hygiene science
    • /
    • v.4 no.3
    • /
    • pp.91-95
    • /
    • 2004
  • This study aims to analyze realities of oral health and related factors, and establish Structural Equation Modeling. The subjects of study were 9,340 elderly over age 65 who took the health examination(the first) for the local insured which National Health Insurance Corporation carried out in the survey area mentioned below from January 2002 to December 2002. The areas surveyed were 4 big cities including Seongbuk-ku, Seoul, 5 medium cities including Wonjusi, Gangwon-do, and 5 Counties including Yeong deok County, Kyeongbuk. Considering location and the scale of population, firstly, big unit areas(metropolitan city, province) were selected according to convenience, secondly, low unit areas(city, county, district) were selected randomly. The subjects were the elderly who took all tests including an oral examination and filled in the questionnaire. Major results from analysis are as follows: 1. Review of Composition Conception Validity As a result of analyzing composition conception validity of SEM including posture test, urine test, blood test, habits of eating, drinking and smoking, oral symptoms, and oral health status, using fit index such as GFI, CFI, TLI, and RMSEA, all were within fit range and composition conception validity was recognized. 2. As a result of analyzing SEM to find the relationship between each factor and oral health status, it was confirmed that all factors except urine test affected oral health status and the synthetic SEM to explain it could be established. In result, we could verify that the elderly of rural areas who had lesser experience of visiting a clinic and oral prophylaxis had a higher rate of caries, missing teeth, and denture need, and drinking and smoking negatively affected the rate of caries, periodontal, and missing teeth. Also, periodontal diseases were observed from 43.2% of the total elderly and much from the lower age. Most of oral disease can be prevented by right oral health behavior. Therefore through oral health professionals from each district public health center of the nation, oral health education for the elderly about right eating habits and oral health care should be carried out systematically and policy change to increase access to dental service is required lest that visiting a dental clinic should be impossible or oral health behaviors such as oral prophylaxis and denture wearing should be neglected by economic, geographical barriers. Also, to establish SEM to explain the relationship between oral health status and systemic health, more accurate test methods and effective index development should be preceded. Because items developed by National Health Insurance Corporation applied to this study without alteration, structuring a model had the uppermost limit. Continual study seems to be needed.

  • PDF

The effects of audit quality on the relationship between deferred tax assets and discretionary accruals (감사품질이 이연법인세자산과 재량적 발생액의 관계에 미치는 영향)

  • Lee, Hyun-Joo;Park, Sang-Seob
    • Management & Information Systems Review
    • /
    • v.35 no.4
    • /
    • pp.169-184
    • /
    • 2016
  • Deferred tax assets (liability) in a company's financial statements are to reflect the temporary difference between taxable income and accounting income and therefore can provide useful information as a proxy for discretionary accruals. In addition, deferred tax assets allow a company to manage its earnings by reviewing the feasibility of the assets' recognition. As such, this study focused on deferred tax assets to examine their relationship with discretionary accruals, which were measured by a modified Jones model (Dechow et al. 1995), and investigated the impact of audit quality on this relationship. In order to control for the effects of tax rate change and measurement credibility, deferred tax assets of 2,670 non-financial firms from 2009 to 2010 were collected as samples for the study. The results of the empirical analysis are as follows. First, the samples as a whole indicated that deferred tax assets have a negative relationship with discretionary accruals in a general sense, but a high-quality audit did not reveal a significant relationship between them. Second, the 1,379 samples with negative discretionary accruals did not reveal a significant relationship between deferred tax assets and discretionary accruals; however, the result showed a significant negative relationship under a high-quality audit. These findings suggest that in the case of negative discretionary accruals, a high-quality audit restricts an earnings management technique that utilizes deferred tax assets and that the assets can be a useful tool for detecting discretionary accruals. The present study is meaningful in that, unlike previous research, it combined the two contrasting roles of deferred tax assets-that of an earnings management detector and an earnings management tool-to examine their general relationship. The study also suggested that audit quality could influence the usefulness of deferred tax assets in providing information on discretionary accruals.

  • PDF

Radiographic evaluation of marginal bone resorption around two types of external hex implants : preliminary study (두 종의 external hex implant의 변연골 흡수에 관한 연구 : 예비연구 (preliminary study))

  • Lee, Ji-Eun;Heo, Seong-Joo;Koak, Jai-Young;Kim, Seong-Kyun;Han, Chong-Hyun
    • The Journal of Korean Academy of Prosthodontics
    • /
    • v.46 no.2
    • /
    • pp.169-174
    • /
    • 2008
  • Statement of problem: Changes of the marginal bone around dental implants have significance not only for the functional maintenance but also for the esthetic success of the implant. It was proposed that bone-retention elements such as microthreads at the coronal part of implant might help maintain the marginal bone level. Purpose: This study was designed to evaluate the effect of microthread configuration within the marginal coronal portion of the implant fixture at the marginal bone changes after loading around two different external hex implants. Material and methods: Twenty-four patients were included and randomly assigned to treatment with $Br{{\aa}}nemark$ system implants (Group 1, rough-surfaced implants, n=20) and Oneplant system implants (Group 2, rough-surfaced neck with microthreads, n=20). Clinical and radiographic examinations were conducted at baseline (implant loading) and 1 year postloading. Data analysis was performed by the SAS statistical package version 9.1.3 (SAS Institute, Cary, NC, USA) and the final model was calculated by the MIXED procedure (three-level ANCOVA) for marginal bone change of each test group at baseline and 1 year follow-up. Results: Comparing to baseline, significant differences were noted in marginal bone level changes for the 2 groups at 1 year follow-up (P<0.05). Group 1 had a mean crestal bone level changes of $0.83{\pm}0.31mm$; Group 2 had a mean crestal bone level changes of $0.44{\pm}0.36mm$. Rough-surfaced with microthreads implants showed significantly less marginal bone loss than rough surfaced neck without microthread implants. Conclusion: A rough surface with microthreads at the implant was beneficial design to maintain the marginal bone level against functional loading.

A Study on Flavorous Taste Components in Kimchis -On Free Amino Acids- (김치의 맛 성분(成分)에 관(關)한 연구(硏究) -유리(遊離) 아미노산(酸)에 관(關)하여 -)

  • Cho, Young;Rhee, Hai-Soo
    • Korean Journal of Food Science and Technology
    • /
    • v.11 no.1
    • /
    • pp.26-31
    • /
    • 1979
  • Free amino acids and total free sugar of kimchi were identified. Free amino acids of kimchis were extracted by 80% ethanol and isolated by ion exchange chromatography. Identification and quantitative determination of individual free amino acids were performed by amino acid autoanalyzer. Free sugar of kimchis was extracted by aqueous ethanol and isolated by ion exchange chromatography. Quantitative determination of it was perfermed by spectrophotometer. The results are summarized as follows: 1. Lysine, histidine, arginine, tryptophan, aspartic acid, threonine, glutamic acid, proline, glycine, alanine, cysteine, valine, methionine, leucine, isoleucine, tyrosine and phenylalanine were found in all kimchis. 2. The change of free amino acid composition during fermentation of kimchis was not observed, but the amount of total free amino acids of fermented kimchi decreased as compared with those of raw kimchi. 3. In kimchi containing 10 ml of fermented anchovy solution/100 g of chinese cabbage, the amount of total free amino acids was more than that of fermented salt kimchi and the characteristic flavor of it was attributed to such amino acids as lysine, aspartic acid, glutamic acid, valine, methionine, isoleucine and leucine. 4. Large amount of free sugar in raw salt kimchi decreased during fermentation, but, after fermentation, significant difference of free sugar content between salt kimchi and kimchi containing fermented anchovy solution was not observed.

  • PDF

Effects of Fermented Rice Wine by Using Mycelium of Phellinus linteus on the Expression of Inflammation-Related Proteins in Human Hepatoma Cells and Rat Liver (상황버섯 균사체를 이용한 발효주가 인체간암세포와 흰쥐 간의 염증관련 단백질 발현에 미치는 영향)

  • Ahn Seung-Min;Lee Jun-Hyuk;Choi Yung-Hyun;Lee Yong-Tae;Chung Kyung-Tae;Jeong Young-Kee;Jo Un-Bock;Choi Byung-Tae
    • Journal of Life Science
    • /
    • v.16 no.1
    • /
    • pp.101-107
    • /
    • 2006
  • We have recently discovered that mycelium of Phellinus linteus, popular medical mushrooms in Korea, possess alcohol dehydrogenase and produce alcohol. In the present study, it was examined that the effect of fermented rice wine made by using mycelium of P. linteus (FLMP) on the expression of in-flammation-related proteins in both $HepG_2$ cells and rats. To examine the effect of FLMP on the morphology and expression of inflammatory proteins in $HepG_2$ cells, the cells were incubated with ethanol, and FLMP for 24 hours, and then analyzed by microscopic observation and Western blot and reverse transcription polymerase chain reaction (RT-PCR). While ethanol induced the morphological change accompanied with cell debris formation and scattering on $HepG_2$ cells, FLMP had no effect. The results of Western blot and RT-PCR analyses showed that the level of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-1 and COX-2 was induced by ethanol, however, FLMP inhibited the expression of these proteins and its mRNAs. In the animal model, the value of flutamate oxaloacetate transaminase and glutamate pyruvate transaminase was significantly increased by administration with ethanol. But the group administrated with FLMP showed lower levels on the changes of these markers compared with ethanol-administrated group. Besides, the results of Western blot and RT-PCR analyses showed that the expression of inflammatory proteins such as iNOS, COX-1 and COX-2 was not affected by FLMP administration in rat liver. About histopathological and immunohistochemical observations, inflammatory loci were markedly decreased in the FLMP-administrated rat compared to ethanol-administrated rats and showed weaker COX-2 and iNOS jmmunoreactions. These results suggested that FLMP showed slight changes on the inflammatory proteins expression compared to ethanol and FLMP may be used as a functional alcoholic beverage.

A Study for the Methodology of Analyzing the Operation Behavior of Thermal Energy Grids with Connecting Operation (열 에너지 그리드 연계운전의 운전 거동 특성 분석을 위한 방법론에 관한 연구)

  • Im, Yong Hoon;Lee, Jae Yong;Chung, Mo
    • KIPS Transactions on Computer and Communication Systems
    • /
    • v.1 no.3
    • /
    • pp.143-150
    • /
    • 2012
  • A simulation methodology and corresponding program based on it is to be discussed for analyzing the effects of the networking operation of existing DHC system in connection with CHP system on-site. The practical simulation for arbitrary areas with various building compositions is carried out for the analysis of operational features in both systems, and the various aspects of thermal energy grids with connecting operation are highlighted through the detailed assessment of predicted results. The intrinsic operational features of CHP prime movers, gas engine, gas turbine etc., are effectively implemented by realizing the performance data, i.e. actual operation efficiency in the full and part loads range. For the sake of simplicity, a simple mathematical correlation model is proposed for simulating various aspects of change effectively on the existing DHC system side due to the connecting operation, instead of performing cycle simulations separately. The empirical correlations are developed using the hourly based annual operation data for a branch of the Korean District Heating Corporation (KDHC) and are implicit in relation between main operation parameters such as fuel consumption by use, heat and power production. In the simulation, a variety of system configurations are able to be considered according to any combination of the probable CHP prime-movers, absorption or turbo type cooling chillers of every kind and capacity. From the analysis of the thermal network operation simulations, it is found that the newly proposed methodology of mathematical correlation for modelling of the existing DHC system functions effectively in reflecting the operational variations due to thermal energy grids with connecting operation. The effects of intrinsic features of CHP prime-movers, e.g. the different ratio of heat and power production, various combinations of different types of chillers (i.e. absorption and turbo types) on the overall system operation are discussed in detail with the consideration of operation schemes and corresponding simulation algorithms.

A Study of a Teaching Plan for Gifted Students in Elementary School Mathematics Classes (일반학급에서의 초등 수학 영재아 지도 방안 연구)

  • Kim, Myeong-Ja;Shin, Hang-Kyun
    • Journal of Elementary Mathematics Education in Korea
    • /
    • v.13 no.2
    • /
    • pp.163-192
    • /
    • 2009
  • Currently, our country operates gifted education only as a special curriculum, which results in many problems, e.g., there are few beneficiaries of gifted education, considerable time and effort are required to gifted students, and gifted students' educational needs are ignored during the operation of regular curriculum. In order to solve these problems, the present study formulates the following research questions, finding it advisable to conduct gifted education in elementary regular classrooms within the scope of the regular curriculum. A. To devise a teaching plan for the gifted students on mathematics in the elementary school regular classroom. B. To develop a learning program for the gifted students in the elementary school regular classroom. C. To apply an in-depth learning program to gifted students in mathematics and analyze the effectiveness of the program. In order to answer these questions, a teaching plan was provided for the gifted students in mathematics using a differentiating instruction type. This type was developed by researching literature reviews. Primarily, those on characteristics of gifted students in mathematics and teaching-learning models for gifted education. In order to instruct the gifted students on mathematics in the regular classrooms, an in-depth learning program was developed. The gifted students were selected through teachers' recommendation and an advanced placement test. Furthermore, the effectiveness of the gifted education in mathematics and the possibility of the differentiating teaching type in the regular classrooms were determined. The analysis was applied through an in-depth learning program of selected gifted students in mathematics. To this end, an in-depth learning program developed in the present study was applied to 6 gifted students in mathematics in one first grade class of D Elementary School located in Nowon-gu, Seoul through a 10-period instruction. Thereafter, learning outputs, math diaries, teacher's checklist, interviews, video tape recordings the instruction were collected and analyzed. Based on instruction research and data analysis stated above, the following results were obtained. First, it was possible to implement the gifted education in mathematics using a differentiating instruction type in the regular classrooms, without incurring any significant difficulty to the teachers, the gifted students, and the non-gifted students. Specifically, this instruction was effective for the gifted students in mathematics. Since the gifted students have self-directed learning capability, the teacher can teach lessons to the gifted students individually or in a group, while teaching lessons to the non-gifted students. The teacher can take time to check the learning state of the gifted students and advise them, while the non-gifted students are solving their problems. Second, an in-depth learning program connected with the regular curriculum, was developed for the gifted students, and greatly effective to their development of mathematical thinking skills and creativity. The in-depth learning program held the interest of the gifted students and stimulated their mathematical thinking. It led to the creative learning results, and positively changed their attitude toward mathematics. Third, the gifted students with the most favorable results who took both teacher's recommendation and advanced placement test were more self-directed capable and task committed. They also showed favorable results of the in-depth learning program. Based on the foregoing study results, the conclusions are as follows: First, gifted education using a differentiating instruction type can be conducted for gifted students on mathematics in the elementary regular classrooms. This type of instruction conforms to the characteristics of the gifted students in mathematics and is greatly effective. Since the gifted students in mathematics have self-directed learning capabilities and task-commitment, their mathematical thinking skills and creativity were enhanced during individual exploration and learning through an in-depth learning program in a differentiating instruction. Second, when a differentiating instruction type is implemented, beneficiaries of gifted education will be enhanced. Gifted students and their parents' satisfaction with what their children are learning at school will increase. Teachers will have a better understanding of gifted education. Third, an in-depth learning program for gifted students on mathematics in the regular classrooms, should conform with an instructing and learning model for gifted education. This program should include various and creative contents by deepening the regular curriculum. Fourth, if an in-depth learning program is applied to the gifted students on mathematics in the regular classrooms, it can enhance their gifted abilities, change their attitude toward mathematics positively, and increase their creativity.

  • PDF

Effect of Ethane 1,2-Dimethane Sulfonate(EDS) on the Apoptosis in the Rat Epididymis (흰쥐 부정소에서의 세포자연사에 미치는 Ethane 1,2-Dimethane Sulfonate(EDS)의 효과)

  • Son, Hyeok-Jun;Lee, Sung-Ho
    • Development and Reproduction
    • /
    • v.10 no.3
    • /
    • pp.203-209
    • /
    • 2006
  • Ethane 1,2-Dimethane sulfonate(EDS), a toxin which specifically kills Leydig cells(LC), has been widely used to prepare the reversible testosterone(T) depletion rat model. Previous studies including our own clearly demonstrated that the dramatic weight loss of the T-dependent accessory sex organs such as epididymis and seminal vesicle in this 'LC knock-out' rats. These weight loss could be derived from massive and abrupt death of the cells via apoptotic process. The present study was performed to test the effect of EDS administration on the expression of some apoptotic genes in the rat epididymis. Adult male Sprague-Dawley rats($300{\sim}350$ g B.W.) were injected with single dose of EDS(75 mg/kg, i.p.) and sacrificed on Weeks 0, 1, 2, 3, 4, 5, 6 and 7. Tissue weights and the numbers of the epididymal sperm were measured. The transcriptional activities of the bcl-2, bax, Fas and Fas ligand(Fas-L) were evaluated by semi-quantitative RT-PCR. As expected, the weights and the sperm counts of epididymis declined progressively after the EDS treatment during Week 1 and 2. These decrements were discontinued with a gradual return towards normal during Weeks $5{\sim}7$, although the maximal recoveries of the epididymal weights(71%) and sperm count(38%) were subnormal on Week 7. The initial level of bcl-2 transcripts persisted to Week 6 then elevated significantly on Week 7. The level of bax transcripts significantly decreased on Week 6, and no remarkable change was found in the rest of the experimental period. The transcripts for the Fas in epididymis elevated during Weeks $1{\sim}2$, returned to normal on Week 3, and the level persisted to the Week 7. Similarly, the level of Fas-L transcripts elevated during Weeks $1{\sim}3$ and returned to normal after Week 4. Our results demonstrated the transient T depletion by EDS administration could induce the changes in expression of the apoptotic genes in rat epididymis. The activation of Fas and Fas-L in the epididymis of EDS-treated rats might be responsible for the initial apototic process and consequently the tissue damage and the sperm loss. Future studies will attempt to determine the precise molecular mechanism(s) of apoptosis in the rat epididymis.

  • PDF