• Korea Trade Review
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• v.47 no.4
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• pp.53-68
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• 2022

It has great significance to estimate CIF-FOB margins of international trade. It certainly helps develop statistics on transport costs of international trade and provides basic data for econometric analysis of transport costs. It also contributes much to our standing the correlation between the margins and trade partners' geographical distance as well as one between the margins and trading products. However, the quality issue of international trade statistics renders it very difficult to derive trustworthy CIF-FOB margin estimates. Utilizing various analytical approaches, this study intended to acquire credible estimates of CIF-FOB margins for Korea's total imports and for country/product specific imports data. Major findings are as follows. First, the average of CIF-FOB margins of Korea's total imports is 7.3% and is generally declining. Second, country level analysis provides credible estimates for CIF-FOB margins of Korea's imports from four partners (Japan, the US, Australia, and Brazil). The differences in margins among these four countries are caused by geographical distance and characteristics of traded products. Third, product level analysis reveals that the margins of gold and passenger vehicles are fairly low while those of primary products tend to be high.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.1838-1842
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• 2004

Gain and phase margins of a first order plus delayed time (FOPDT) process controlled by generalized predictive controller (GPC) are related to the control parameters ${\lambda}$ (control move suppression parameter) and ${\alpha}$ (smoothing filter coefficient) and the normalized delay of the process. Variation ranges of gain and phase margins are determined. It is shown that the margins cannot be assigned independently for a wide range of variation and the range is narrowing by increase of the normalized delay of the process. And finally curves are given to use for adjustment of the controller parameters in order to obtain a specific pair of gain and phase margins.

• International Journal of Control, Automation, and Systems
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• v.6 no.3
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• pp.460-466
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• 2008

This paper deals with the stability analysis of a missile guidance loop employing an integrated proportional navigation guidance law. The missile guidance loop is formulated as a closed-loop control system consisting of a linear time-invariant feed-forward block and a time-varying feedback gain. Based on the circle criterion, we have defined the concept of absolute stability margins and obtained the gain and phase margins for the system assuming 1 st order missile/autopilot dynamics. The correlation between the absolute stability margins and the margins derived from the frozen system analysis is also discussed.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.10
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• pp.4989-4992
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• 2012

Purpose: Guide-wire localization (GWL) has been a standard technique for many years. Excision of nonpalpable malignant breast lesions with clear surgical margins reduces the risk of undergoing re-excision. The objective of the present study was to evaluate the efficacy of GWL biopsy for assessing surgical margins. Methods: This retrospective study concerned 53 patients who underwent GWL biopsy for non-palpable breast lesions and breast carcinoma diagnosed by histological examination. Age of the patients, tumour size, radiographic findings, breast density specifications, specimen volumes, menopausal status and family history of the patients and surgical margin status were recorded. Results: Median age was 53.3 years, median tumour size was 1.5 cm and median specimen volume was $71.5cm^3$. In fifteen patients (28%) DCIS and in 38 patients (72%) invasive ductal carcinoma was diagnosed. There was positive surgical margins in twenty eight (52.8%) patients. The median distance to the nearest surgical margin was 7.2 mm in clear surgical margins. Younger age and denser breast specifications were found as statistically significant factors for surgical margin status. Median age of the patients who had positive margins was 49.4 years where it was 56.9 years in the patients with negative margins (p=0.04). 79% of the patients with positive margins had type 3-4 pattern breast density according to BIRADS classification as compared to 48% in the patients who had negative margins (p=0.03). Some 38 patients who had positive or close surgical margins received re-excision (72%). Conclusion: Positive margin rates may be higher because of inherent biological differences and diffuse growth patterns in younger patients. There are also technical difficulties that are relevant to denser fibroglandular tissue in placing hooked wire. High re-excision rates must be taken into consideration while performing GWL biopsy in non-palpable breast lesions.

• Anatomy and Cell Biology
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• v.50 no.1
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• pp.41-47
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• 2017

This study investigated the topographic relationships among the eyeball and four orbital margins with the aim of identifying the correlation between orbital geometry and eyeball protrusion in Koreans. Three-dimensional (3D) volume rendering of the face was performed using serial computed-tomography images of 141 Koreans, and several landmarks on the bony orbit and the cornea were directly marked on the 3D volumes. The anterior-posterior distances from the apex of the cornea to each orbital margin and between the orbital margins were measured in both eyes. The distances from the apex of the cornea to the superior, medial, inferior, and lateral orbital margins were 5.8, 5.8, 12.0, and 17.9 mm, respectively. Differences between sides were observed in all of the orbital margins, and the distances from the apex of the cornea to the superior and inferior orbital margins were significantly greater in females than in males. The anterior-posterior distance between the superior and inferior orbital margins did not differ significantly between males (6.3 mm) and females (6.2 mm). The data obtained in this study will be useful when developing practical guidelines applicable to forensic facial reconstruction and orbitofacial surgeries.

• Restorative Dentistry and Endodontics
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• v.27 no.1
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• pp.34-43
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• 2002

The purpose of this study was to compare microleakage and marginal hybrid layer in class V restorations using two one-bottle adhesives and one self-etching adhesive. Class V cavity preparations with occlusal margins in enamel and gingival margins in dentin were pre-pared on buccal and lingual surfaces of 30 extracted human molar teeth. Prepared teeth were randomly divided into three treatment groups (n=30) and restored with three adhesives and composites: Single Bond/Filtek Z-250 (Group 1), Prime&BondNT/Esthet.X (Group 2), UniFil Bond/UniFil F (Group 3). For microleakage, samples were stored in room temperature water for 24 hours, thermocycled stained with 2% methylene blue dye, sectioned into halves, scored and analysed using Mann-whitney test and Wilcoxon signed rank sum test. For marginal hybrid layer, samples were sectioned into halves, treated with 10% phosphoric acid for 5 seconds, stored in 5% NaOCL solution for 24 hours, dried and gold coated. Occlusal and gingival margins of each sample were inspected under SEM. The results of this study were as follows ; 1. Microleakage at the occlusal margins was not evident in group 1 and group 2, but it showed in group 3 (p<0.05). 2. Microleakage in group 1 and group 3 was significantly lower than in group 2 at gingival margins (p<0.05). 3. Microleakage at gingival margins was greater than at occlusal margins in group 1 and group 2, but microleakage at occlusal margins was greater than at gingival margins in group 3 (p<0.05). 4. In group 1 and group 2, no gaps at occlusal margins showed. But gaps showed in group 3. Occlusal margins were free from a hybrid layer in all groups 5. The thickness of the marginal hybrid layers was 2.5~5 $\mu\textrm{m}$ thick in group 5 $\mu\textrm{m}$ thick in group 2 and 1.5 $\mu\textrm{m}$ thick in group 3. 6 There was no corelation between microleakage and thickness of marginal hybrid layer. In coclusion, the effect of dentin adhesives on microleakge in class V composite restorations was excellent when one-bottle adhesives were applied on enamel margin, and it was good when a self-etching adhesive was applied on dentinal margin. There was no corelation between microleakage and thickness of marginal hybrid layer.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.107.4-107
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• 2001

In this paper, the guaranteed stability margins of LQ optimal regulators for a performance index with cross-product terms are suggested in the discrete-time case. An example for the LQ optimal regulator of an inverted pendulum system is given to demonstrate the validity of the suggested stability margins.

• Archives of Plastic Surgery
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• v.32 no.4
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• pp.454-460
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• 2005

Dematofibrosarcoma protuberans(DFSP) is a moderate-degree malignant tumor with high recurrence rate and low metastasis rate, from soft tissue. Principle of treatment is wide excision or Mohs micrographic surgery(MMS). Although wide excision has been performed with surgical margins of 2-5 cm until nowadays, there are problems of preservation of surrounding normal tissue. Therefore the authors tried to identify desirable surgical margins and operative method. From January 1999 to April 2003, 12 patients with DFSP were operated. We applied different surgical margins and operative methods according to the location of lesions. On the face, we performed MMS with surgical margin of 3-4 mm in 2 cases although there are problems of operation time and expense. But on the extremities and trunk, we performed authors' method to begin excising with surgical margins of 1 cm and excise extensively with MMS by 1 cm in 4 cases after April, 2001 although we had performed wide excision with surgical margin of 3 cm in 6 cases before. There was no recurrence or metastasis in the follow-up period. So we think that author's method is effective in surgical excision of DFSP

• The Journal of Korean Academy of Prosthodontics
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• v.25 no.1
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• pp.161-179
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• 1987

To study the mechanical behaviors of the margins of porcelain-fused-to-metal crown on the posterior teeth, 5 types of margins on the lower first molar were chosen, and then the finite element models were constructed. 50kg forces were applied to the porcelain on the axial wall supported by the metal vertically. The displacements and stresses of the porcelain-fused-to-metal crown were analyzed to investigate the influence of the type of margins. The results were as follows; 1. High tensile stresses were exhibited on the porcelain of the portion of the coronal line angle insufficient metallic support. 2. In case metal coping had a good supporting form to vertical force, uniform compressive stresses were exhibited on their supporting form. 3. Tensile stresses in the inframetallic margin on the series of the shoulder with a bevel margins were decreased in the bevel portion. 4. Principal stresses on the metal of the chamfer marginal portion were decreased comparing with the series of the shoulder margins. 5. The noticeable compressive stress gradients were exhibited between axial cement layer and metal on the series of the shoulder margins. 6. The principal stresses on the marginal cement layer were higher than that of the occlusal surface and axial wall.

• Progress in Medical Physics
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• v.35 no.1
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• pp.1-9
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• 2024

Margin inclusion or exclusion remains the most critical and controversial aspect of stereotactic radiosurgery (SRS) for metastatic brain tumors. This review aimed to examine the available literature on the impact of margins in SRS of brain metastasis and to assess the response of some medical physicists on the use of these margins. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses method was used to review articles published in PubMed, Embase, and Science Direct databases from January 2012 to December 2022 using the following keywords: planning target volume, brain metastasis, margin, and stereotactic radiosurgery. A simple survey consisting of five questions was completed by ten medical physicists with experience in SRS treatment planning. The results were analyzed using IBM SPSS Statistics version 26.0. Of the 1,445 articles identified, only 38 articles were chosen. Of these, eight papers were deemed relevant to the focus of this review. These papers showed an increase in the risk of radionecrosis, whereas differences in local control were variable as the margin increased. In the survey, the response rate to whether or not to use margins in SRS, a critical question, was 50%. Margin addition increases the risk of radio necrosis. The local control rate varies among treatment modalities and cannot be generalized. From the survey, no consensus was reached regarding the use of these margins. This calls for further deliberations among professionals directly involved in SRS.