• 제목/요약/키워드: Error Term

Search Result 1,009, Processing Time 0.027 seconds

Outcome of patients with neuroblastoma aged less than 1 year at diagnosis (진단 시 1세 이하인 신경모세포종 환자의 치료성적)

  • Suh, Jung Min;Lee, Sang Goo;Yoo, Keon Hee;Sung, Ki Woong;Koo, Hong Hoe;Kim, Ju Youn;Cho, Eun Joo;Lee, Suk Koo;Kim, Jhingook;Lim, Do Hoon
    • Clinical and Experimental Pediatrics
    • /
    • v.52 no.1
    • /
    • pp.93-98
    • /
    • 2009
  • Purpose : The purpose of this study was to evaluate the clinical characteristics and outcomes of patients with neuroblastoma aged less than 1 year. Methods : From January 1997 to December 2007, 41 patients aged less than 1 year were diagnosed with neuroblastoma. Patients were divided into 3 risk groups according to the stage of the disease and N-myc amplification. Low-risk patients underwent surgery with (stage 2) or without (stage 1) short-term chemotherapy. Intermediate-risk patients underwent chemotherapy and surgery with or without local radiation therapy. High-risk patients underwent chemotherapy, surgery, radiation therapy, and high-dose chemotherapy/autologous stem cell rescue (HDCT/ASCR). Results : While tumor relapse occurred in only 1 patient, 7 patients died of treatment-related toxicities. Causes of treatment- related death included infection during conventional chemotherapy in 5 patients and acute myocarditis during HDCT/ASCR in 2 patients. The overall 5-year survival (${\pm}$ standard error) and 5-year event-free survival (EFS) rates after diagnosis for all 41 patients were $82.8{\pm}5.9%$ and $80.0{\pm}$6.3%$, respectively, with a median follow-up of 58 (9-137) months. The 5-year EFS rates for low-risk, intermediate-risk, and high-risk patients were 100%, $68.4{\pm}10.8%$, and $66.7{\pm}19.3%$, respectively. Conclusion : Increased efforts to reduce infection-associated toxicity deaths during conventional chemotherapy are needed to further improve the survival of patients with neuroblastoma aged less than 1 year.

Impact of Sulfur Dioxide Impurity on Process Design of $CO_2$ Offshore Geological Storage: Evaluation of Physical Property Models and Optimization of Binary Parameter (이산화황 불순물이 이산화탄소 해양 지중저장 공정설계에 미치는 영향 평가: 상태량 모델의 비교 분석 및 이성분 매개변수 최적화)

  • Huh, Cheol;Kang, Seong-Gil;Cho, Mang-Ik
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.13 no.3
    • /
    • pp.187-197
    • /
    • 2010
  • Carbon dioxide Capture and Storage(CCS) is regarded as one of the most promising options to response climate change. CCS is a three-stage process consisting of the capture of carbon dioxide($CO_2$), the transport of $CO_2$ to a storage location, and the long term isolation of $CO_2$ from the atmosphere for the purpose of carbon emission mitigation. Up to now, process design for this $CO_2$ marine geological storage has been carried out mainly on pure $CO_2$. Unfortunately the $CO_2$ mixture captured from the power plants and steel making plants contains many impurities such as $N_2$, $O_2$, Ar, $H_2O$, $SO_2$, $H_2S$. A small amount of impurities can change the thermodynamic properties and then significantly affect the compression, purification, transport and injection processes. In order to design a reliable $CO_2$ marine geological storage system, it is necessary to analyze the impact of these impurities on the whole CCS process at initial design stage. The purpose of the present paper is to compare and analyse the relevant physical property models including BWRS, PR, PRBM, RKS and SRK equations of state, and NRTL-RK model which are crucial numerical process simulation tools. To evaluate the predictive accuracy of the equation of the state for $CO_2-SO_2$ mixture, we compared numerical calculation results with reference experimental data. In addition, optimum binary parameter to consider the interaction of $CO_2$ and $SO_2$ molecules was suggested based on the mean absolute percent error. In conclusion, we suggest the most reliable physical property model with optimized binary parameter in designing the $CO_2-SO_2$ mixture marine geological storage process.

Errors in Net Ecosystem Exchanges of CO2, Water Vapor, and Heat Caused by Storage Fluxes Calculated by Single-level Scalar Measurements Over a Rice Paddy (단일 높이에서 관측된 저장 플럭스를 사용할 때 발생하는 논의 이산화탄소, 수증기, 현열의 순생태계교환량 오차)

  • Moon, Minkyu;Kang, Minseok;Thakuri, Bindu Malla;Lee, Jung-Hoon
    • Korean Journal of Agricultural and Forest Meteorology
    • /
    • v.17 no.3
    • /
    • pp.227-235
    • /
    • 2015
  • Using eddy covariance method, net ecosystem exchange (NEE) of $CO_2$ ($F_{CO_2}$), $H_2O$ (LE), and sensible heat (H) can be approximated as the sum of eddy flux ($F_c$) and storage flux term ($F_s$). Depending on strength and distribution of sink/source of scalars and magnitude of vertical turbulence mixing, the rates of changes in scalars are different with height. In order to calculate $F_s$ accurately, the differences should be considered using scalar profile measurement. However, most of flux sites for agricultural lands in Asia do not operate profile system and estimate $F_s$ using single-level scalars from eddy covariance system under the assumption that the rates of changes in scalars are constant regardless of the height. In this study, we measured $F_c$ and $F_s$ of $CO_2$, $H_2O$, and air temperature ($T_a$) using eddy covariance and profile system (i.e., the multi-level measurement system in scalars from eddy covariance measurement height to the land surface) at the Chengmicheon farmland site in Korea (CFK) in order to quantify the differences between $F_s$ calculated by single-level measurements ($F_s_{-single}$ i.e., $F_s$ from scalars measured by profile system only at eddy covariance system measurement height) and $F_s$ calculated by profile measurements and verify the errors of NEE caused by $F_s_{-single}$. The rate of change in $CO_2$, $H_2O$, and Ta were varied with height depending on the magnitudes and distribution of sink and source and the stability in the atmospheric boundary layer. Thus, $F_s_{-single}$ underestimated or overestimated $F_s$ (especially 21% underestimation in $F_s$ of $CO_2$ around sunrise and sunset (0430-0800 h and 1630-2000 h)). For $F_{CO_2}$, the errors in $F_s_{-single}$ generated 3% and 2% underestimation of $F_{CO_2}$ during nighttime (2030-0400 h) and around sunrise and sunset, respectively. In the process of nighttime correction and partitioning of $F_{CO_2}$, these differences would cause an underestimation in carbon balance at the rice paddy. In contrast, there were little differences at the errors in LE and H caused by the error in $F_s_{-single}$, irrespective of time.

A Study on the Volatility of Global Stock Markets using Markov Regime Switching model (마코브국면전환모형을 이용한 글로벌 주식시장의 변동성에 대한 연구)

  • Lee, Kyung-Hee;Kim, Kyung-Soo
    • Management & Information Systems Review
    • /
    • v.34 no.3
    • /
    • pp.17-39
    • /
    • 2015
  • This study examined the structural changes and volatility in the global stock markets using a Markov Regime Switching ARCH model developed by the Hamilton and Susmel (1994). Firstly, the US, Italy and Ireland showed that variance in the high volatility regime was more than five times that in the low volatility, while Korea, Russia, India, and Greece exhibited that variance in the high volatility regime was increased more than eight times that in the low. On average, a jump from regime 1 to regime 2 implied roughly three times increased in risk, while the risk during regime 3 was up to almost thirteen times than during regime 1 over the study period. And Korea, the US, India, Italy showed ARCH(1) and ARCH(2) effects, leverage and asymmetric effects. Secondly, 278 days were estimated in the persistence of low volatility regime, indicating that the mean transition probability between volatilities exhibited the highest long-term persistence in Korea. Thirdly, the coefficients appeared to be unstable structural changes and volatility for the stock markets in Chow tests during the Asian, Global and European financial crisis. In addition, 1-Step prediction error tests showed that stock markets were unstable during the Asian crisis of 1997-1998 except for Russia, and the Global crisis of 2007-2008 except for Korea and the European crisis of 2010-2011 except for Korea, the US, Russia and India. N-Step tests exhibited that most of stock markets were unstable during the Asian and Global crisis. There was little change in the Asian crisis in CUSUM tests, while stock markets were stable until the late 2000s except for some countries. Also there were stable and unstable stock markets mixed across countries in CUSUMSQ test during the crises. Fourthly, I confirmed a close relevance of the volatility between Korea and other countries in the stock markets through the likelihood ratio tests. Accordingly, I have identified the episode or events that generated the high volatility in the stock markets for the financial crisis, and for all seven stock markets the significant switch between the volatility regimes implied a considerable change in the market risk. It appeared that the high stock market volatility was related with business recession at the beginning in 1990s. By closely examining the history of political and economical events in the global countries, I found that the results of Lamoureux and Lastrapes (1990) were consistent with those of this paper, indicating there were the structural changes and volatility during the crises and specificly every high volatility regime in SWARCH-L(3,2) student t-model was accompanied by some important policy changes or financial crises in countries or other critical events in the international economy. The sophisticated nonlinear models are needed to further analysis.

  • PDF

Price Volatility, Seasonality and Day-of-the Week Effect for Aquacultural Fishes in Korean Fishery Markets (수산물 시장에서의 양식 어류 가격변동성.계절성.요일효과에 관한 연구 - 노량진수산시장의 넙치와 조피볼락을 중심으로 -)

  • Ko, Bong-Hyun
    • The Journal of Fisheries Business Administration
    • /
    • v.40 no.2
    • /
    • pp.49-70
    • /
    • 2009
  • This study proviedes GARCH model(Bollerslev, 1986) to analyze the structural characteristics of price volatility in domestic aquacultural fish market of Korea. As a case study, flatfish and rock-fish are analyzed as major species with relatively high portion in an aspect of production volume among fish captured in Korea. For analyzing, this study uses daily market data (dating from Jan 1 2000 to June 30, 2008) published by the Noryangjin Fisheries Wholesale Market which is located in Seoul of Korea. This study performs normality test on trading volume and price volatility of flatfish and rock-fish as an advanced empirical approach. The normality test adopted is Jarque-Bera test statistic. As a result, first, a null hypothesis that "an empirical distribution follows normal distribution" was rejected in both fishes. The distribution of daily market data of them were not only biased toward positive(+) direction in terms of kurtosis and skewness, but also characterized by leptokurtic distribution with long right tail. Secondly, serial correlations were found in data on market trading volume and price volatility of two species during very long period. Thirdly, the results of unit root test and ARCH-LM test showed that all data of time series were very stationary and demonstrated effects of ARCH. These statistical characteristics can be explained as a reasonable ground for supporting the fitness of GARCH model in order to estimate conditional variances that reveal price volatility in empirical analysis. From empirical data analysis above, this study drew the following conclusions. First of all, from an empirical analysis on potential effects of seasonality and the day of week on price volatility of aquacultural fish, Monday effects were found in both species and Thursday and Friday effects were also found in flatfish. This indicates that Monday is effective in expanding price volatility of aquacultural fish market and also Monday has higher effects upon the price volatility of fish than other days of week have since it has more new information for weekend. Secondly, the empirical analysis led to a common conclusion that there was very high price volatility of flatfish and rock-fish. This points out that the persistency parameter($\lambda$), an index of possibility for current volatility to sustain similarly in the future, was higher than 0.8-equivalently nearly to 1-in both flatfish and rock-fish, which presents volatility clustering. Also, this study estimated and compared and model that hypothesized normal distributions in order to determine fitness of respective models. As a result, the fitness of GARCH(1, 1)-t model was better than model where the distribution of error term was hypothesized through-distribution due to characteristics of fat-tailed distribution, was also better than model, as described in the results of basic statistic analysis. In conclusion, this study has an important mean in that it was introduced firstly in Korea to investigate in price volatility of Korean aquacultural fishery products, although there was partially a limited of official statistic data. Therefore, it is expected that the results of this study will be useful as a reference material for making and assessing governmental policies. Also, it is looked forward that the results will be helpful to build a fishery business plan as and aspect of producer, and also to take timely measures to potential price fluctuations of fishery products in market. Hence, it is advisable that further studies related to such price volatility in fishery market will extend and evolve into a wider variety of articles and issues in near future.

  • PDF

An Esthetic Restoration of the Missing Maxillary Anterior Teeth with the Rotational Path RPD: A Case Report (회전삽입로 국소의치를 이용한 심미적 상악 전치부 수복 증례)

  • Lee, Ji-Hye;Lim, So-Min;Jung, Hye-Eun;Park, Chan-Jin;Cho, Lee-Ra;Kim, Dae-Gon
    • Journal of Dental Rehabilitation and Applied Science
    • /
    • v.27 no.2
    • /
    • pp.209-222
    • /
    • 2011
  • Missing anterior teeth can be replaced using any of a number of methods. Patients may choose to replace missing teeth with a prosthesis that is either removable, fixed, or retained with implants. For patients faced with financial, anatomical, and/or esthetic limitations, the edentulous region can be restored successfully and esthetically with a properly designed and fabricated rotational path RPD. The rotational path RPD is a partial removable dental prosthesis that incorporates a curved, arcuate, or variable path of placement allowing one or more of the rigid components of the framework to gain access to and engage an undercut area. The rigid retainer must gain access to the infrabulge portion of the tooth by rotating into place. Either a minor connector or proximal plate provides retention through its intimate contact with a proximal tooth surface. A specially designed dovetails or asymmetric rest seats provides support and embracing effects. Correctly designed and fabricated rotational path RPD can provide improved esthetics, cleanliness, and retention. But rotational path RPDs are technique sensitive since the rotational path RPD has little margin of laboratory error that rigid retainers cannot be adjusted like conventional clasps can, RPD framework must be remade once the retention is lost. The sufficient understanding of the concept for the rotational path RPD is required for clinically successful treatment. This clinical report describes in detail the theoretical, laboratory considerations and the treatment of a patient with an anterior maxillary edentulous area treated by an AP path rotational RPD that had a difficulty in long term maintenance and describes another clinical case in which more reasonable treatment procedures were approached after analyzing the former case.

A Proposal to Control System and the Problems of the Problems of the Report about Supply and Demand for Medical Technicians and Management Policy ("의료기사인력수급에 관한 보고서"의 문제점과 관리제도의 개선방안)

  • Kim, Sang-Hyun;Lim, Yongmoo
    • Journal of Korean Ophthalmic Optics Society
    • /
    • v.13 no.4
    • /
    • pp.25-30
    • /
    • 2008
  • Purpose: In this paper, we have analyzed the problems of the Oh's report which is used to the basic data for supply and demand of medical technicians and studied a proposal for improvement to control system and supply and demand of korean optometrists. Methods: We have analyzed errors of Oh's report including supply and demand for medical technicians and management policy, expecting number for future optician, inaccurate estimation by limited data (employment rate, retirement rate, mortality rate) and an incorrect method of measurement for future supply and demand. Results: Oh's report showed the 18% error for estimation of supply which exclude the irregular entrance students. The estimation of supply was calculated by graduation rate 62.6% (college and University of Technology are 78.9% and 85.98% respectively), employment rate 65.8% (the average employment between 2002 and 2007 is 73.96%) and retirement rate is 2.3% (the retirement of pharmacists is 1.3%) but it showed the significant differences to objective data. For estimate the suitable ratio of optometrists to the population, the ratio use of medical facilities by an age group was used, and suggested spectacle wearers 1,280 persons (populations 2,928 persons) per optometrist but the different from reference of Germany (4,706 persons), America (1,789 persons) and Korea (1,825 persons/an optometrist) are applied to estimation on supply. This report applied the low employment rate and argued that maintain the present situation, but claimed that utilize unemployment persons. The above result has induced double weighting effect on estimation of supply. Conclusions: To solve the related problems of supply and demand, we have to make a search for exact data and optimum application model, have to take an example of nation similar job category as Germany and the research result of the job satisfaction into consideration. After we get the integrated research result, we must carried out the policy with fairness and balance for the estimation of supply and demand. Therefore exact research is required prior to beginning policy establishment, government and related group have to make a clear long-term plan and permanent organization for medical technician to establish supply and demand of medical technician.

  • PDF

Legislative Study on the Mitigation of the Burden of Proof in Hospital Infection Cases - Focusing on the revised Bürgerliches Gesetzbuch - (병원감염 사건에서 증명책임 완화에 관한 입법적 고찰 - 개정 독일민법을 중심으로 -)

  • Yoo, Hyun Jung
    • The Korean Society of Law and Medicine
    • /
    • v.16 no.2
    • /
    • pp.159-193
    • /
    • 2015
  • Owing to causes such as population aging, increased use of various medical devices, long-term hospitalization of various patients with reduced immune function such as cancer, diabetes, and organ transplant patients, and the growing size of hospitals, hospital infections are continuing to increase. As seen in the MERS crisis of 2015, hospital infections have become a social and national problem. In order to prevent damage due to such hospital infections, it is necessary to first strictly implement measures to prevent hospital infections, while, on the other hand, providing proper relief of damage suffered due to hospital infections. However, the mainstream attitude of judicial precedents relating to hospital infection cases has been judged to in fact shift responsibility over damages due to hospital infections on the patient. In light of the philosophy of the damage compensation system, whose guiding principle if the fair and proper apportionment of damages, there is a need to seek means of drastically relaxing the burden of proof on the patient's side relative to conventional legal principles for relaxing the burden of proof, or the theory of de facto estimation. In relation to such need, the German civil code (Burgerliches Gesetzbuch), which defines contracts of medical treatment as typical contracts under the civil code, and has presumption of negligence provisions stipulating that, in cases such as hospital infections which were completely under the control of the medical care providers, if risks in general medical treatment have been realized which cause violations of the life, body, or health of patients, error on the part of the person providing medical care is presumed, was examined. Contracts of medical treatment are entered into very frequently and broadly in the everyday lives of the general public, with various disputes owing thereto arising. Therefore, it is necessary to, by defining contracts of medical treatment as typical contracts under the civil code, regulate the content of said contracts, as well as the proof of burden when disputes arise. If stipulations in the civil code are premature as of yet, an option may be to regulate through a special act, as is the case with France. In the case of hospital infection cases, it is thought that 'legal presumption of negligence' relating to 'negligence in the occurrence of hospital infections,' which will create a state close to equality of arms, will aid the resolution of the realistic issue of the de facto impossibility of remedying damages occurring due to negligence in the process of occurrence of hospital infections. Also, even if negligence is presumed by law, as the patient side is burdened with proving the causal relationships, such drastic confusion as would occur if the medical care provider side is found fully liable if a hospital infection occurs may be avoided. It is thought that, alongside such efforts, social insurance policy must be improved so as to cover the expenses of medical institutions having strictly implemented efforts to prevent hospital infections in the event that they have suffered damages due to a hospital infection accident, and that close future research and examination into this matter will be required.

  • PDF

The Relationship between Internet Search Volumes and Stock Price Changes: An Empirical Study on KOSDAQ Market (개별 기업에 대한 인터넷 검색량과 주가변동성의 관계: 국내 코스닥시장에서의 산업별 실증분석)

  • Jeon, Saemi;Chung, Yeojin;Lee, Dongyoup
    • Journal of Intelligence and Information Systems
    • /
    • v.22 no.2
    • /
    • pp.81-96
    • /
    • 2016
  • As the internet has become widespread and easy to access everywhere, it is common for people to search information via online search engines such as Google and Naver in everyday life. Recent studies have used online search volume of specific keyword as a measure of the internet users' attention in order to predict disease outbreaks such as flu and cancer, an unemployment rate, and an index of a nation's economic condition, and etc. For stock traders, web search is also one of major information resources to obtain data about individual stock items. Therefore, search volume of a stock item can reflect the amount of investors' attention on it. The investor attention has been regarded as a crucial factor influencing on stock price but it has been measured by indirect proxies such as market capitalization, trading volume, advertising expense, and etc. It has been theoretically and empirically proved that an increase of investors' attention on a stock item brings temporary increase of the stock price and the price recovers in the long run. Recent development of internet environment enables to measure the investor attention directly by the internet search volume of individual stock item, which has been used to show the attention-induced price pressure. Previous studies focus mainly on Dow Jones and NASDAQ market in the United States. In this paper, we investigate the relationship between the individual investors' attention measured by the internet search volumes and stock price changes of individual stock items in the KOSDAQ market in Korea, where the proportion of the trades by individual investors are about 90% of the total. In addition, we examine the difference between industries in the influence of investors' attention on stock return. The internet search volume of stocks were gathered from "Naver Trend" service weekly between January 2007 and June 2015. The regression model with the error term with AR(1) covariance structure is used to analyze the data since the weekly prices in a stock item are systematically correlated. The market capitalization, trading volume, the increment of trading volume, and the month in which each trade occurs are included in the model as control variables. The fitted model shows that an abnormal increase of search volume of a stock item has a positive influence on the stock return and the amount of the influence varies among the industry. The stock items in IT software, construction, and distribution industries have shown to be more influenced by the abnormally large internet search volume than the average across the industries. On the other hand, the stock items in IT hardware, manufacturing, entertainment, finance, and communication industries are less influenced by the abnormal search volume than the average. In order to verify price pressure caused by investors' attention in KOSDAQ, the stock return of the current week is modelled using the abnormal search volume observed one to four weeks ahead. On average, the abnormally large increment of the search volume increased the stock return of the current week and one week later, and it decreased the stock return in two and three weeks later. There is no significant relationship with the stock return after 4 weeks. This relationship differs among the industries. An abnormal search volume brings particularly severe price reversal on the stocks in the IT software industry, which are often to be targets of irrational investments by individual investors. An abnormal search volume caused less severe price reversal on the stocks in the manufacturing and IT hardware industries than on average across the industries. The price reversal was not observed in the communication, finance, entertainment, and transportation industries, which are known to be influenced largely by macro-economic factors such as oil price and currency exchange rate. The result of this study can be utilized to construct an intelligent trading system based on the big data gathered from web search engines, social network services, and internet communities. Particularly, the difference of price reversal effect between industries may provide useful information to make a portfolio and build an investment strategy.

The GOCI-II Early Mission Ocean Color Products in Comparison with the GOCI Toward the Continuity of Chollian Multi-satellite Ocean Color Data (천리안해양위성 연속자료 구축을 위한 GOCI-II 임무 초기 주요 해색산출물의 GOCI 자료와 비교 분석)

  • Park, Myung-Sook;Jung, Hahn Chul;Lee, Seonju;Ahn, Jae-Hyun;Bae, Sujung;Choi, Jong-Kuk
    • Korean Journal of Remote Sensing
    • /
    • v.37 no.5_2
    • /
    • pp.1281-1293
    • /
    • 2021
  • The recent launch of the GOCI-II enables South Korea to have the world's first capability in deriving the ocean color data at geostationary satellite orbit for about 20 years. It is necessary to develop a consistent long-term ocean color time-series spanning GOCI to GOCI-II mission and improve the accuracy through validation using in situ data. To assess the GOCI-II's early mission performance, the objective of this study is to compare the GOCI-II Chlorophyll-a concentration (Chl-a), Colored Dissolved Organic Matter (CDOM), and remote sensing reflectances (Rrs) through comparison with the GOCI data. Overall, the distribution of GOCI-II Chl-a corresponds with that of the GOCI over the Yellow Sea, Korea Strait, and the Ulleung Basin. In particular, a smaller RMSE value (0.07) between GOCI and GOCI-II over the summer Ulleung Basin confirms the GOCI-II data's reliability. However, despite the excellent correlation, the GOCI-II tends to overestimate Chl-a than the GOCI over the Yellow Sea and Korea Strait. The similar over-estimation bias of the GOCI-II is also notable in CDOM. Whereas no significant bias or error is found for Rrs at 490 nm and 550 nm (RMSE~0), the underestimation of Rrs at 443 nm contributes to the overestimation of GOCI-II Chl-a and CDOM over the Yellow Sea and the Korea Strait. Also, we show over-estimation of GOCI-II Rrs at 660 nm relative to GOCI to cause a possible bias in Total suspended sediment. In conclusion, this study confirms the initial reliability of the GOCI-II ocean color products, and upcoming update of GOCI-II radiometric calibration will lessen the inconsistency between GOCI and GOCI-II ocean color products.