• International conference on construction engineering and project management
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• 2022.06a
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• pp.1059-1066
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• 2022

In 2020, it was estimated that more than 2.4 million households in South Korea are over 30 years old. That is, more than 40% of all houses in Korea are old and that they require proper rehabilitation. The two options to improve poor living conditions are reconstruction and remodeling. Compared to reconstruction, remodeling has advantages in terms of the construction period, cost, and environmental impact. As such, the current Korean regulations are more favorable for remodeling than reconstruction. Typically, several candidate floor plans are presented in the early stages of an apartment remodeling project. Extracting information about bearing walls and other structural elements from the multiple plans to compare those plans quantitatively is one of the essential tasks during the early stage of a project. To cope with this task, an automated data extraction method for walls and slabs from before and after remodeling plans is developed. Through the developed program, load-bearing walls, non-bearing walls, slabs, and weight changes after remodeling can be analyzed and visualized in a fast and automated manner.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1B
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• pp.33-40
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• 2008

Intensive rainfalls in wet season (June~September) result in serious flood damage which is about 95% of natural hazard in Korea. Recently, in order to cope with repeated flood hazard, comprehensive flood control plans have been carried out in large basins in Korea. The plans suggest structural alternative plans for flood mitigation as well as non-structural plans. In this study, a practical method using a decision tree was developed to systematically allocate structural facilities for flood control, which maximizes the flood control capacity in a basin. This study also presents a practical guidance to organize structural defensive alternatives for a comprehensive flood control plan in a large basin.

• Progress in Medical Physics
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• v.25 no.4
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• pp.199-204
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• 2014

The purpose of this study is to evaluate the dosimetric outcome of the field-in-field (FIF) plans compared with tangential wedged beams (TWB) plans for whole breast irradiation of breast cancer patients. Twenty patients with right-sided breast cancer and 10 patients with left-sided breast cancer were retrospectively enrolled in this study. We generated a FIF plan and a TWB plan for each patient to compare dosimetric outcomes. The dose the homogeneity index (HI), the conformity index (CI) and the uniformity index (UI) were defined and used for comparison of the dosimetric outcome of the planning target volume (PTV). To compare the dosimetric outcome of the organs at risk, the mean dose ($D_{mean}$) and the percentage of volumes receiving more than 10, 20 and 30 Gy of the ipsilateral lung and heart were used. The FIF plans had significantly lower HI (p=0.002), higher UI (p=0.000) and CI (p=0.000) than those of the TWB plans, which means that the FIF plans were better than the TWB plans in the dosimetric comparisons of the PTV. The $V10_{lung}$ ($17.1{\pm}7.1$ vs. $18.6{\pm}6.6%$, p=0.020) and $V30_{lung}$ ($10.3{\pm}5.1%$ vs. $10.7{\pm}5.2%$, p=0.000) were lower with the FIF plans compared with those of the TWB plans, with statistical significance. For the left-sided breast cancer patients, $D_{mean}$ of the heart ($2.6{\pm}1.3$ vs. $3.2{\pm}1.4$ Gy, p=0.000), $V20_{heart}$ ($3.4{\pm}2.6$ vs. $3.6{\pm}2.8%$, p=0.005) and $V30_{heart}$ ($2.6{\pm}2.3%$ vs. $2.9{\pm}2.4%$, p=0.004) were significantly lower for the FIF plans in comparison with those of the TWB plans. The FIF plans increased the dose homogeneity, conformity and uniformity of the target volume for the whole-breast irradiation compared with the TWB plans. Moreover, FIF plans reduced the doses to the ipsilateral lung and heart.

• Journal of Korean Society for Quality Management
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• v.23 no.1
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• pp.41-49
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• 1995

This paper suggests optimal accelerated constant stress life tests in Exponential distribution. The relationship between the log-mean life and the loaded stress is assumed to be linear. Optimal plans considering mean square errors of maximum likelihood estimators of the log mean life and test costs are obtained. We consider accelerated life tests with two stress levels, and as data types, failure censoring( type II) and time censoring(type I) data are used. We propose the procedure to obtain the optimal plans for each case. Some examples are also included.

• Journal of Korean Institute of Industrial Engineers
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• v.3 no.2
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• pp.99-106
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• 1977

A double sampling procedure with zero acceptance number for the first sample whose operating characteristic closely matches that of a given single sampling plan and whose combined sample size does not exceed that of the given single sampling plan is proposed. The proposed double sampling plans corresponding to the MIL-STD-105D plans are tabulated and it is found that their ASN's are considerably smaller than those of corresponding MIL-STD-105D single or double sampling plans.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2005.05a
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• pp.922-926
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• 2005

Progressively censored variables sampling plans are proposed for the lot acceptance of parts whose life follows Weibull distribution with known shape parameter. Progressive type-II censoring gives us not only time to failure but also degradation information. So, one can construct more flexible and more cost effective sampling plans. Design parameters of our sampling plan are determined by using the usual two-point approach.

• Journal of the Korean Statistical Society
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• v.29 no.4
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• pp.435-441
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• 2000

Ko(1998, 1999) proposed certain flexible two-stage plans that could be served as one-step interim analysis in on-going clinical trials. The proposed Plans are optimal simultaneously in both a Bayes and a Neyman-Pearson sense. The Neyman-Pearson interpretation is that average expected sample size is being minimized, subject just to the two overall error rates $\alpha$ and $\beta$, respectively of first and second kind. The Bayes interpretation is that Bayes risk, involving both sampling cost and wrong decision losses, is being minimized. An example of this correspondence are given by using a binomial setting.

• Journal of Korean Institute of Industrial Engineers
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• v.5 no.1
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• pp.53-57
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• 1979

The concept of AOQL in designing Dodge's continuous sampling plans is modified to include probabilistic consideration reflecting the prior knowledge about the process average fraction defectives, and a new design criterion called AOQL, which eliminates some of the drawbacks of the AOQL criterion is proposed. AOQL, approach provides more economical sampling plans in many cases, and can be used even when only limited amount of prior information is available.

• Communications for Statistical Applications and Methods
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• v.12 no.1
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• pp.11-18
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• 2005

Assume that the life times of the units under test follow the Rayleigh distribution and the test is terminated at a pre assigned time. Acceptance sampling plans are developed for this situation. The minimum sample size necessary to ensure the specified average life are obtained and the operating characteristic values of the sampling plans and producer's risk are given. An example is given to illustrate the methodology.

• Communications for Statistical Applications and Methods
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• v.6 no.1
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• pp.143-150
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• 1999

Ko(1998) proposed a procedure to enhance the efficiency of double sampling plans by allowing second-stage sample size and critical region to depend on first-stage evidence using constraint optimization approaches. In this study further developments of such plans by incorporating several practically possible researcher's aims into the optimization are considered. Comparisons are made with the optimal ordinary double sampling plan and also among them It is observed that it is to some extent possible to match the details of the optimization to certain qualitative methodological aims.