• Journal of Korea Foundry Society
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• v.23 no.1
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• pp.40-46
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• 2003

Semisolid forming requires alloys with non-dendritic microstructure of the thixotropy. Recently, low pouring temperture method without stirring, i.e. liquidus casting has been found out new fabrication method of the semisolid metals. Effects of melt superheat and mold conditions on the globulization of primary Al of $AlSi_7Mg$ alloy were investigated in gravity casting process without stirring. The microstructures of primary Al as function of melt superheat and mold temperature show globular, rosette and dendritic shapes. The conditions for globular microstructure of primary Al were low melt superheat < 35 K and low mold temperature < 500 K. The thermal conditions for globular microstructure of primary Al were undercooled melt at early solidification stages and slow cooling < 0.6 K/s. It was found that the initial microstructure was maintained throughout the solidification and the globules of primary Al can be obtained by high nucleation of fine and spherical nuclei due to enhanced undercooling of melt.

• Journal of Communications and Networks
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• v.16 no.2
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• pp.140-145
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• 2014

In this paper, we propose an anti-interference cooperative spectrum sharing strategy for cognitive system, in which a secondary system can operate on the same spectrum of a primary system. Specifically, the primary system leases a fraction of its transmission time to the secondary system in exchange for cooperation to achieve the target rate. To gain access to the spectrum of the primary system, the secondary system needs to allocate a fraction of bandwidth to help forward the primary signal. As a reward, the secondary system can use the remaining bandwidth to transmit its own signal. The secondary system uses different bandwidth to transmit the primary and its own signal. Thus, there will be no interference felt at primary and secondary systems. We study the joint optimization of time and bandwidth allocation such that the transmission rate of the secondary system is maximized, while guaranteeing the primary system, as a higher priority, to achieve its target transmission rate. Numerical results show that the secondary system can gain significant improvement with the proposed strategy.

• The Journal of the Korean dental association
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• v.58 no.3
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• pp.169-179
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• 2020

The purpose of this study was to investigate the principal reasons for primary teeth extractions and the tooth type extracted in children. 1159 patients were selected in this study. Dental records and radiographs were reviewed and age, gender, medical history, type of tooth extracted and the reasons for extraction were collected. The data were statistically analyzed using Chi-square test. Total 2078 primary teeth were extracted. Central incisors(34.1%) were most frequently extracted. Extractions due to physiological mobility(77.5%) were the most frequent followed by caries(13.8%), orthodontic(3.9%), trauma(1.7%). Reason for the extraction was different according to age (p = 0.000), but there was no difference according to gender (p = 0.109). While extractions due to physiological mobility predominated overall, reason for extraction was different according to the tooth type. There was no previous treatment in 54.6% of primary teeth extracted due to caries. Excluded physiological mobility, caries are the most common reason for extraction of primary teeth. The importance of preventive care should be emphasized in order to preserve primary teeth and improve children's oral health.

• Journal of Periodontal and Implant Science
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• v.38 no.2
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• pp.253-262
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• 2008

Background: Incomplete flap coverage or early exposure over implants and/or barrier membranes have a negative effect on bone regeneration. In cases of using regenerative techniques, complete soft tissue coverage of the implant area is necessary to promote adequate conditions for guided bone regeneration. Primary socket closure may be difficult, when periosteal releasing incision is only used, due to the opening left by extracted tooth. Therefore, Soft tissue grafting techniques are used to achieve primary soft tissue closure. Materials and Methods: Soft tissue grafting techniques, with or without barrier membranes, were performed for primary closure in four cases of immediate placements. Three different methods were used (CTG, VIP-CT, Palatal advanced flap). Clinical results of the grafting were evaluated. Result: One case showed early exposure of cover-screw and, no other complications were noted. In the others, Primary closure was achieved by soft tissue grafting techniques. One of the cases, Graft showed partial necrosis, but there were no exposure over implants and/or barrier membranes. Conclusion: The use of grafting techniques, in immediate implant placement, can predictably obtain primary closure of extraction sockets, thereby providing predictable bone formation and improved implant results.

• Journal of Communications and Networks
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• v.14 no.5
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• pp.471-480
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• 2012

Reliable detection of primary user activity increases the opportunity to access temporarily unused bands and prevents harmful interference to the primary system. By extracting a global decision from local sensing results, cooperative sensing achieves high reliability against multipath fading. For the effective combining of sensing results, which is generalized by a likelihood ratio test, the fusion center should learn some parameters, such as the probabilities of primary transmission, false alarm, and detection at the local sensors. During the training period in supervised learning, the on/off log of primary transmission serves as the output label of decision statistics from the local sensor. In this paper, we extend unsupervised learning techniques with an expectation maximization algorithm for cooperative spectrum sensing, which does not require an external primary transmission log. Local sensors report binary hard decisions to the fusion center and adjust their operating points to enhance learning performance. Increasing the number of sensors, the joint-expectation step makes a confident classification on the primary transmission as in the supervised learning. Thereby, the proposed scheme provides accurate parameter estimates and a fast convergence rate even in low signal-to-noise ratio regimes, where the primary signal is dominated by the noise at the local sensors.

• The Journal of Korean Obstetrics and Gynecology
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• v.32 no.4
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• pp.170-180
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• 2019

Objectives: The purpose of this study is to report the case of Korean medicine treatment on primary ovarian insufficiency. Methods: The patient in this case was 29-year-old female who was diagnosed with primary ovarian insufficiency. She had irregular menstruation and hypomenorrhea more than 6 months. She also suffered from hot flash and vaginal dryness. She was treated over 1 year with Korean medicine treatment, such as herbal medicine, acupuncture, and pharmacopuncture. We assessed the clinical symptoms, menstrual status and serum hormone level during the treatment. Results: After treatment, symptoms of primary ovarian insufficiency were relieved, level of serum FSH decreased and level of serum E2 increased. We maintained the treatment over 1 year and kept follow-up measurements of serum hormone level. Conclusions: This study shows that Korean medicine treatment can be effective in treating primary ovarian insufficiency. The report suggests the long treatment procedure for primary ovarian insufficiency.

• Journal of Sasang Constitutional Medicine
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• v.28 no.4
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• pp.350-360
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• 2016

Objective The aim of this study was to report significant improvement of primary insomnia in a Soyangin Cold-related diarrhea accompanied by abdominal pain Symptomatic pattern Patient. Methods The patients were diagnosed with Soyangin Cold-related diarrhea accompanied by abdominal pain Symptomatology(身寒腹痛亡陰證) and treated with Hyungbangjihwang-tang(荊防地黃湯). The primary outcome measures for this study were condition of sleep using a questionnaire with Pittsburgh Sleep Quality Index (PSQI) Secondary outcome assessment included change of original symptoms such as patient's digestion, sweating and feces. Result The symptoms of primary insomnia improved by the end of the a treatment period without side effect. original symptoms were also changed. Conclusions This result show Hyungbangjihwang-tang(荊防地黃湯) can be used to treat primary insomnia in a Soyangin Cold related Mangeum Symptomatic Pattern accompanied by abdominal pain Symptomatology(身寒腹痛亡陰證). Meaning and process of primary insomnia are different according to Sasang Constitutions.

• Korean Journal of Head & Neck Oncology
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• v.34 no.2
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• pp.53-56
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• 2018

Despite adequate diagnostic work-up, unknown primary carcinoma(UPC) of the head and neck cannot be detected in approximately 2- 3% of patients.(1,2) There are several explanations for a cervical metastasis in the absence of a primary tumor. Here in, we report 2 patients, who were diagnosed with nasopharyngeal cancer after treatment of unknown primary cancer of the neck. Both patients had radical neck dissections and chemoradiation therapy, but 1 patient showed nasopharyngeal cancers 4 years after treatment and the other patient at 9 months after treatment for the unknown primary cancer. Therefore, we report 2 cases of nasopharyngeal cancer, which were diagnosed after treatment of unknown head and neck primary site.

• The Journal of the Korean dental association
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• v.57 no.10
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• pp.569-578
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• 2019

The purpose of this retrospective study was to compare outcome of preformed stainless steel crown restorations according to depth of caries in primary molars. The study subjects consisted primary molars having dentin caries extending at least one-fourth of dentin without signs and symptoms of irreversible pulpitis. A total 295 primary molars received preformed stainless steel crown restorations without any base materials were included in this study. Survival rates were compared using a Kaplan-Meier analysis test. There was no significant difference between depth of caries and survival period in primary molars. And also there was no significant difference with or without pulp therapy. The results of this study suggest that neither the amount of caries nor pulp therapy affect the survival period of primary molars significantly. Proper restoration is more important to achieve sealing for stopping caries progression.

• Journal of Digestive Cancer Research
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• v.5 no.1
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• pp.32-36
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• 2017

In unresectable stage IV colorectal cancer, the role of palliative surgery is not defined clearly. The palliative surgery can be categorized into two surgeries; first, palliative primary tumor resection; second, palliative metastatectomy. Several retrospective studies reported initial palliative systemic chemotherapy in unresectable stage IV colorectal cancer did not increase primary tumor related complications such as obstruction, perforation and hemorrhage, so they insisted that primary tumor resection in asymptomatic stage IV colorectal cancer should be preserved. However, in terms of overall survival and cancer-specific or progression-free survival, several retrospective studies, especially using population-based big data, reported favored survivals in palliative primary tumor resection group. And also several studies reported that palliative metastatectomy such as liver resection without resection of lung metastasis showed better overall survivals. But those results from those studies came from retrospective studies and are likely to be affected by selection bias. Prospective randomized studies are needed to define the benefit of palliative primary tumor resection and metastatectomy in unresectable stage IV colorectal cancer. However, based on the updated evidences, the dogma that palliative primary tumor resection should be preserved in asymptomatic unresectable stage IV colorectal cancer should be questioned.