• Journal of Korean Society of Water and Wastewater
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• v.22 no.6
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• pp.647-655
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• 2008

Sewer Rehabilitation Project (SRP) is planed, designed and constructed to perform its intended performance as sewerage delivery systems. Recently, a subject of performance evaluation methodology development for SRP has become a great deal of concern among researchers in Korea. From the view point of Sewage Treatment Plant (STP), however, the estimation of improvement efficiency for SRP is in lack of reliability due to the fact that affections for the treatment efficiency and operating condition are not reflected on SRP design and construction. In this study, statistical methodology was used in the analysis of data, which are taken during 1,186 days ($1^{st}$ Jan. 2005 - $31^{th}$ Mar. 2008) from the influent, effluent and operating conditions of full-scale STP($25,000m^3/d$). Then the effect of SRP on the influent characteristics and operating conditions changing was compared and evaluated. Results from the statistical evaluation show that SRP causes characteristic changes in influent and exerts a significant effect especially on the performance of STP.

• The Korean Journal of Applied Statistics
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• v.32 no.2
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• pp.173-185
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• 2019

Causal questions are prevalent in scientific research, for example, how effective a treatment was for preventing an infectious disease, how much a policy increased utility, or which advertisement would give the highest click rate for a given customer. Causal inference theory in statistics interprets those questions as inferring the effect of a given intervention (treatment or policy) in the data generating process. Causal inference has been used in medicine, public health, and economics; in addition, it has received recent attention as a tool for data-driven decision making processes. Many recent datasets are observational, rather than experimental, which makes the causal inference theory more complex. This review introduces key concepts and recent trends of statistical causal inference in observational studies. We first introduce the Neyman-Rubin's potential outcome framework to formularize from causal questions to average treatment effects as well as discuss popular methods to estimate treatment effects such as propensity score approaches and regression approaches. For recent trends, we briefly discuss (1) conditional (heterogeneous) treatment effects and machine learning-based approaches, (2) curse of dimensionality on the estimation of treatment effect and its remedies, and (3) Pearl's structural causal model to deal with more complex causal relationships and its connection to the Neyman-Rubin's potential outcome model.

• Imaging Science in Dentistry
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• v.33 no.4
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• pp.223-229
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• 2003

Purpose: To compare the effects of the conservative treatment and operative treatment by observation of osseous changes of the TMJ and mandibular asymmetry in condylar fracture patients. Materials and Methods: 33 condylar fracture patients (17 with conservative and 16 with operative treatment) were included in this study. After a minimum of 6 months after the surgical procedure, patients were given a follow up examination of the osseous changes using a transcranial view. Differences in the osseous changes of both groups were compared and the asymmetry indices were calculated on a postero-anterior skull view. Results: The TMJ of the operative treatment group showed more significant osseous changes than the conservative treatment group. The affected TMJ showed more significant osseous changes than the unaffected TMJ in the both groups. The unaffected TMJ of the conservative group and the affected TMJ of the operative group showed significant osseous changes. The mandibular asymmetry indices in the conservative and operative group were 5.12 and 7.30 respectively at the time of treatment, and 2.39 and 3.41 respectively at the follow-up. But the mandibular asymmetry between the both groups showed no statistical differences. Conclusion: The TMJ of the operative group showed more significant osseous changes than the conservative group, but the mandibular asymmetry between the both groups showed no statistical difference.

• Journal of Korean Medicine Rehabilitation
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• v.23 no.4
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• pp.1-7
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• 2013

Objectives The purpose of this study is to compare the effects of ShinBaro pharmacopuncture and Jungsongouhyul pharmacopuncture on whiplash injury by traffic accident. Methods This study was carried out on 30 patients who received treatment in Jaseng Hospital of Korean Medicine. 30 patients were divided ShinBaro pharmacopuncture group and Jungsongouhyul pharmacopuncture group. Visual analog scale (VAS) and neck disability index (NDI) were compared after treatment. Results 1) Both the ShinBaro group and Jungsongouhyul group showed significant improvement in the visual analog scale (VAS) and neck disability index (NDI) after 3 weeks of treatment. 2) The VAS and NDI of the ShinBaro group decreased gradually with treatment. The VAS scores showed significant improvement up to week 2, but although week 3 showed further improvement compared to week 2, the difference did not reach statistical significance. The NDI scores showed significant improvement consistantly throughout the treatment period. 3) The VAS and NDI of the Jungsongouhyul group decreased with treatment also. The VAS scores significantly improved up to week 2, but though week 3 showed further improvement in comparison to week 2, the difference did not reach statistical significance. The NDI scores showed significant improvement consistantly throughout the treatment period. 4) Although the ShinBaro group showed a swifter decline than the Jungsongouhyul group in both VAS and NDI scores, the difference was not statistically significant. Conclusions We found out that ShinBaro pharmacopuncture group and Jungsongouhyul pharmacopuncture group is effective and useful in whiplash injury by traffic accident. And, further studies will be needed.

• The Journal of Korean Physical Therapy
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• v.15 no.3
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• pp.388-411
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• 2003

The purpose of this study has been conducted to reduce the lower limbs' spasticity of the patients with hemiplegia caused by cerebral stroke of apoplexy and find differences about spasticity effects among each group. The objects of this study covered 24 patients with hemiplgia who are either in the oo hospital in Daegu or under treatment from home to hospital. The objects fall into three groups which are a group of neurological development treatment, a group of functional stimulus treatment and a group of neurological development treatment and functional stimulus treatment. The result of this study were as follows : 1) The neurological development treatment has been found to reduce the lower limbs' spasticity of patients with hemiplegia caused by cerebral stroke of apoplexy and compared to before-treatment, the MAS value of spasticity has been shown to be statistically meaningful ,and gradually over the period of between 4 weeks and 8 weeks(P <.05). 2) The functional electric stimulus treatment has been shown to reduce the lower limb's spasticity of patients with hemiplegia caused by cerebral stroke of apoplexy and compared to before-treatment, the MAS value of spasticity was statistically meaningful and compared to 4 weeks, even at the time of 8 weeks, the MAS value of spasticity have shown statistical meaningness. (P <.05) 3) When neurological development treatment and functional electric stimulus treatment was applied at the same time, the lower limbs' spasticity of patients with hemiplegia was reduced meaningfully(P <.05). Compared to before-treatment at the time of 4 weeks, the MAS value of spasticity was statistically meaningful and compared to 4 weeks at the time of 8 weeks the MAS value of spasticity was also statistically meaningful(P <.05) 4) In the case of time-based MAS value of each group, functional electric stimulus treatment reduced the spasticity more meaningfully than neurological development treatment, and the group of same application of functional electric stimulus treatment and neurological development treatment showed better statistical meaningness than functional electric stimulus treatment alone(P <.05) and finally the group of same application of neurological development treatment and functional electric stimulus treatment showed more meaningful difference than neurological development treatment alone(P <.05)

• Journal of the Korean Society of School Health
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• v.6 no.1
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• pp.9-44
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• 1993

An explorative and descriptive study in order to determine the effect of family structure and other socio-demographic variables on health behavior, belief, locus, and value and utilization of public health service was carried out. Data were collected from 1,653 subjects randomly sampled in three areas, Seoul, Kyunggi province, and Cheju province. From Seoul 849 subjects were selected, 397 subjects Kyunggi, and 407 subjects from Cheju, respectively. Self-reporting questionaires were administered during the period from March to June, 1992. The major findings were as follows: 1) The subjects visited herb-doctor's at irregular intervals mainly to have tonic medicine prepared. They preferred herb-doctor's rather than with doctors at clinics and hospitals. Statistically significant difference was found among the regions studied (p<0.05). 2) The reason for visiting hospitals was primarily for treatment of diseases. They preferred hospital because they felt that the hospitals offer much highly reliable treatment services as well as medical accessibility. For the purpose of hospital utilization, statistically significant differences existed among sex, educational level, family type and region. However, no significance was found among sex, educational level, and region (p<0.05). 3) The subjects utilized general hospitals mainly for diagnosis and treatment of diseases. They preferred general hospitals because of their much better facilities and reliability. Statistical significance was found among sex, educational level, and region (p<0.05). 4) The subjects visited dentist at irregular intervals basis. They visited once half a year or three to four months. their purpose of visit was mainly for diagnosis and treatment of diseases. Statistical significance differences were found among educational level, region and economic standard (p<0.05). 5) Whenever their illnesses were mild and the pharmacies was located in nearby they visited to pharmacies. They visited once a month and patient medicines. Statistically significant differences were found among sex, educational level and region (p<0.05). 6) The subjects believed that herb medicine was quite efficacious for treatment of some diseases, particularly by information handed down through time-honored tradition and experience. However, they recognized that the efficacy of folk medicine can vary with type and severity of diseases. Statistical significance was among sex, educational level, region and economic standard (p<0.05). 7) The reason why subjects believed that pray and superstition are effective for treatment of certain type of diseases, particularly in neuropathy, was the belief in God's almighty. Statistically significant differences were found among sex, educational level, regions and economic standard (p<0.05). 8) Most of subjects under same condition preferred western medicine because they believed that it is more scientific and prompts in showing therapeutic effect. Statistical significance was not found in the choice of type of public health service among, regions. But significant differences were found among sex, educational level and region (p<0.05). 9) The subjects looked for pharmacy if they thought the symptom was mild. However, they visited hospitals for chronic disease and general hospitals for emergency treatment. Statistical significances were found among educational level, region and economic standard (p<0.05). 10) Although most of students wanted to have a healthy life as for the component of health standard and value, they think that they are not healthy (p<0.05). As for the health behavior, significant difference was found in the proportion of smoking and drinking between educational level and region (p<0.05). The health locus was affected by educational level, and health behavior was influenced by region, sex and educational level. The utilization of type of public health service was influenced by family type and region, and health belief by region and educational level, and the health values by region and economic standard respectively, most of correlation showed statistical significance. Among them, the highest correlation was seen between locus of control and external/internal locus of control, which is quite obvious. The correlation between health belief and behavior was the next highest, but still low (0.343). All the other variables are low but significant except only a few of those. These findings indicate that health education should be incorporated into the curriculum so as to develop desirable health habit, and ability of self-control in accordance with their growth stages. A systematic and scientific understanding on the herb/folk medicine is needed, and greater reliability of the utilization of public health services are is still required. Health policy for equal distribution of health service throughout the country along the hierarchical health service system and complementary mutual assistance and cooperation among various health organizations are also required.

• Communications for Statistical Applications and Methods
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• v.15 no.5
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• pp.727-735
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• 2008

Consider a clinical trial in which the main end-point is survival. Suppose after the start of the study an intermediate event occurs which may be influenced by a covariate(or treatment). In many clinical studies the occurrence of an intermediate event may change the survival distribution. This investigation develops two-stage model which, in the first stage, models the effect of covariate on the intermediate event and models the relationship between survival time and covariate as well as the intermediate event. In this paper, the two-stage model is presented in order to model intermediate event and a test based on this model is also provided. A numerical simulations are carried out to evaluate its overall significance level.

• Communications for Statistical Applications and Methods
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• v.25 no.3
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• pp.275-282
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• 2018

This paper discusses the use of projections for the sums of squares in the analyses of variance for two-way nested design data. The model for this data is assumed to only have random effects. Two different sizes of experimental units are required for a given experimental situation, since nesting is assumed to occur both in the treatment structure and in the design structure. So, variance components are coming from the sources of random effects of treatment factors and error terms in different sizes of experimental units. The model for this type of experimental situation is a random effects model with more than one error terms and therefore estimation of variance components are concerned. A projection method is used for the calculation of sums of squares due to random components. Squared distances of projections instead of using the usual reductions in sums of squares that show how to use projections to estimate the variance components associated with the random components in the assumed model. Expectations of quadratic forms are obtained by the Hartley's synthesis as a means of calculation.

• Communications for Statistical Applications and Methods
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• v.12 no.3
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• pp.705-712
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• 2005

Biplot is a graphical display of the rows and columns of an n${\times}$p data matrix. In particular, Gabriel (1995) suggested the MANOVA biplot using singular value decomposition (SVD) with the averages of response variables according to treatment groups. But his biplot may cause wrong results by disregarding them when there exist covariate effects. In this paper, we will provide the MANCOA biplot based on the SVD with the parameter estimates for MANCOVA model when there exist covariate effects.

• Proceedings of the Korean Statistical Society Conference
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• 2000.11a
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• pp.27-32
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• 2000

To overcome boundary problems with wavelet regression, we propose a simple method that reduces bias at the boundaries. It is based on a combination of wavelet functions and low-order polynomials. The utility of the method is illustrated with simulation studies and a real example. Asymptotic results show that the estimators are competitive with other nonparametric procedures.