고상반응법과 착체중합법으로 합성된 SrAl₂O₄: Eu²⁺, Dy³⁺ 축광성 형광체의 특성 및 열적 안정성 평가

김태호,황해진,김진호,황광택,한규성,Kim, Tae-Ho,Hwang, Hae-Jin,Kim, Jin-Ho,Hwang, Kwang-Taek,Han, Kyu-Sung 한국결정성장학회 2016 한국결정성장학회지 Vol.26 No.5

Characteristics of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors synthesized by solid state reaction and polymerized complex method were comparatively analyzed. In order to evaluate thermal stability of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors at high temperature, phosphorescent properties of $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ were investigated with thermal treatment at $1250^{\circ}C$ under reducing atmosphere, which was the general heat treatment conditions for ceramic manufacturing process. The phosphorescent properties of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphors synthesized by solid state reaction and polymerized complex method were investigated. The crystal structure and crystallite size were observed through XRD analysis. Microstructure and particle size of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphors were analyzed by SEM and PSA. Photoluminescence and afterglow characteristics of thermally treated $SrAl_2O_4:Eu^{2+}$, $Dy^{3+}$ phosphorescent phosphors were measured by spectrofluorometer.

국내 청년실업의 단.장기 변동구조 추정

김태호,Kim, Tae-Ho 한국통계학회 2008 응용통계연구 Vol.21 No.2

The government employment statistics show the close comovement of the whole domestic unemployment rate with the youth unemployment rate for the past 10 years, implying the dominant influence of the unemployment of the youth age. This study investigates the structure of the short-run variation and the process of the long-run adjustment in the unemployment rates of the youth and middle ages by formulating the dynamic equation system. The estimation result consistently reflects the vulnerability of the youth class in the aggravation of the employment condition. The effect of exogenous changes is found to be persistent in the unemployment rates of both ages, which appear to have similar structures of the long-run time path. However, the youth unemployment rate turns out to have a relatively long adjustment process to the long-run equilibrium.

시장간 단기적 불균형 관계에 따른 균형오차의 추정

김태호,Kim, Tae-Ho 한국통계학회 2008 응용통계연구 Vol.21 No.2

This study attempts to perform the statistical tests for the comovement of the stock prices between Korea and U.S. by using the weekly data instead of the usual daily data. The restoring pattern, from the short-run disequilibrium to the long-run equilibrium point, is also carefully estimated if the long-run relationships exist between the stock prices. The cointegrating relations between the stock prices appear to begin to hold during the period of the financial crisis. It is found to be consistently estimated that the equilibrium error is slowly eliminated till the end of the financial crisis, while quickly removed after the period.

미국농무성의 돼지개체식별계획

김태호,Kim, Tae-Ho 대한양돈협회 1989 養豚 Vol.11 No.11

부동산 규제정책에 따른 광역 주택가격의 변동간 불균형 검정

김태호,안지희,Kim, Tae-Ho,Ann, Ji-Hee 한국통계학회 2010 응용통계연구 Vol.23 No.3

The government real estate policy has repeatedly relaxed and reinforced controls under the mutually contradictory targets. Switching over the supporting policy after the IMF crisis to the regulating policy from 2003, the government housing policy began to generate ill effects due to various regulations. This stud carefully investigates and statistically tests the transmissions of variations in the housing prices between the metropolitan areas in the early stage of the preceding administration, under the effect of the supporting scheme, and those in the late stage, under the effect of the restricting scheme. The distinctive feature between the two periods is found to be much simplified interrelationships of the price variations in the latter period. Consolidated leading role of capital sphere, by concentrated economic strength, suggest the obvious imbalance between variations in the metropolis housing prices.

공적분벡터의 안정성에 대한 실증연구

김태호,황성혜,김미연,Kim, Tae-Ho,Hwang, Sung-Hye,Kim, Mi-Yun 한국통계학회 2005 응용통계연구 Vol.18 No.3

공적분검정은 변수들간의 장기적 균형관계에 따른 공적분벡터가 표본기간 동안 일정하다는 가정하에서 실시된다. 따라서 기존의 연구들은 변수들 사이의 공적분관계를 안정적 장기균형관계로 해석해왔으나 장기균형관계가 존재해도 유일하지 않을 수 있으며, 표본기간 중 중요한 사건이 발생하는 경우 이러한 관계에 영향을 미처 안정성이 반드시 성립될 수 없다는 사실은 간과해왔다. 본 연구에서는 추정된 공적분벡터가 안정성을 유지하는가를 확인하기 위해 추가로 통계적 검정을 실시하였다. 공적분회귀모형 모수의 안정성을 검정하는 방식을 세분${\cdot}$체계화하여 공적분백터의 안정성 및 변동형태를 검색하는 실증분석에 적용시켜 보았다.

실업률 변동구조의 분석과 전환점 진단

김태호,황성혜,이영훈,Kim, Tae-Ho,Hwang, Sung-Hye,Lee, Young-Hoon 한국통계학회 2005 응용통계연구 Vol.18 No.2

One of the basic assumptions of the regression models is that the parameter vector does not vary across sample observations. If the parameter vector is not constant for all observations in the sample, the statistical model is changed and the usual least squares estimators do not yield unbiased, consistent and efficient estimates. This study investigates the regression model with some or all parameters vary across partitions of the whole sample data when the model permits different response coefficients during unusual time periods. Since the usual test for overall homogeneity of regressions across partitions of the sample data does not explicitly identify the break points between the partitions, the testing the equality between subsets of coefficients in two or more linear regressions is generalized and combined with the test procedure to search the break point. The method is applied to find the possibility and the turning point of the structural change in the long-run unemployment rate in the usual static framework by using the regression model. The relationships between the variables included in the model are reexamined in the dynamic framework by using Vector Autoregression.

경기동행과 후행 관계에서 실업률 변동성향의 추정

김태호,정재화,Kim, Tae-Ho,Jung, Jae-Hwa 한국통계학회 2012 응용통계연구 Vol.25 No.1

통계청의 고용통계는 고용환경의 변화와 관련된 정보는 제공하지 않으며, 실업이 경기변동에 따라 변화하지만 함께 발표되는 월간산업동향과 관련된 분석은 제대로 이루어지지 않고 있다. 본 연구는 고용환경의 급변시 우리 사회의 주요 관심사인 실업 및 실망실업의 성향을 국내외 가격변수와 연계해 경기동행과 경기후행의 관계 안에서 통계적으로 분석하였다. 실망실업률은 일반 실업률에 비해 단기적 불균형에서 장기균형으로의 회복 속도가 빠르며, 특히 대부분 변수들의 변화에 상대적으로 민감하게 반응하는 것으로 추정되어 현실을 대변하는 의미있는 통계지표임을 시사한다.

2D 어레이 다이오드 검출기를 통한 IMRT 계산선량의 정확성 평가 및 효용성 연구

김태호,오승종,김민주,정원균,정진범,김재성,김시용,서태석,Kim, Tae-Ho,Oh, Seung-Jong,Kim, Min-Joo,Jung, Won-Gyun,Chung, Jin-Beom,Kim, Jae-Sung,Kim, Si-Yong,Suh, Tae-Suk 한국의학물리학회 2011 의학물리 Vol.22 No.2

In this study, we evaluated the effect of grid size on dose calculation accuracy using 2 head & neck and 2 prostate IMRT cases and based on this study's findings, we also evaluated the efficiency of a 2D diode array detector for IMRT quality assurance. Dose distributions of four IMRT plan data were calculated at four calculation grid sizes (1.25, 2.5, 5, and 10 mm) and the calculated dose distributions were compared with measured dose distributions using 2D diode array detector. Although there was no obvious difference in pass rate of gamma analysis with 3 mm/3% acceptance criteria for the others except 10 mm grid size, we found that the pass rates of 2.5, 5 and 10 mm grid size were decreased 5%, 20% and 31.53% respectively according to the application of the fine acceptance criteria, 3 mm/3%, 2 mm/2% and 1 mm/1%. The calculation time were about 11.5 min, 4.77 min, 2.95 min, and 11.5 min at 1.25, 2.5, 5, and 10 mm, respectively and as the grid size increased to double, the calculation time decreased about one-half. The grid size effect was observed more clearly in the high gradient area than the low gradient area. In conclusion, 2.5 mm grid size is considered acceptable for most IMRT plans but at least in the high gradient area, 1.25 mm grid size is required to accurately predict the dose distribution. These results are exactly same as the precious studies' results and theory. So we confirmed that 2D array diode detector was suitable for the IMRT QA.

한미 월간 경기동향의 선행성 분석

김태호,Kim, Tae-Ho 한국통계학회 2009 응용통계연구 Vol.22 No.1

This study attempts to perform the statistical test for the causality between the Korean and the U.S. business conditions in association with the lead-lag relationship between the domestic stock price and the business condition. Their causal relationships are clearly identified after the outbreak of the IMF financial crisis. The vector autoregression for the corresponding period appears to reflect the strong interrelationships between the market variables and the dependency of the domestic business conditions on the U.S. market. The estimation results validate the leading effect of the stock price and the U.S. business behavior.