ATOS 80 고장력강의 용접 패스에 따른 용접부 방사선검사에 관한 연구

백정환(Jung-Hwan Baek),최병기(Byung-Ky Choi) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.6

In constructing all kinds of equipment and steel structure, parts with discontinuities such as weld defects formed in the welded structure can generate fatigue cracks that results in damage or accidents. In this study, weld zones are investigated with X-rays and the latent images are put on film. Weld zone defects can be verified by developing the film. As weld defects are investigated by radiographic testing and correlated with the welding condition, more appropriate welding conditions can be found. According to the result of X-ray radiographic inspection of butt welding ATOS 80 high-strength steel with a thickness of 12 ㎜, the best conditions for welding without creating weld defects are 4 weld-passes, a protective gas of 20% CO₂ and 80% Ar, a protective gas flow of 20L/min, a welding current of 200A, an arc voltage of 24V, a welding speed of 14.4 ㎝/min, a welding rod angle of 50°, a welding gap of 5 ㎜ with a ceramic base, and sand pre-heating to 160° Celsius prior to welding.

ATOS 80 고장력강의 보호가스량에 따른 용접부 방사선검사에 관한 연구

백정환(Jung-Hwan Baek),최병기(Byung-Ky Choi) 한국생산제조학회 2012 한국생산제조학회지 Vol.21 No.6

In constructing all kinds of equipment and steel structures, discontinuous areas such as weld defects formed in a welded structure tend to generate cracks that will result in damage. In this study, ATOS high-strength steel welding becomes important in butt welding where the tensile strength of the steel is over 80kg/mm2. Structural discontinuities such as joints are more susceptible cracks in part due to their repeated loading and fatigue crack growth. The quality of parts produced depend or the shielded amounts of steel and on the skill of the welders in making strong welds. It is true that there are many factors that can be used to generate a lot of research in this area. However geometry and load conditions due to the combined effects with many issues could be solved through this study. Butt welding material at a plate thickness of 12t in ATOS 80 high-strength steel with a 4 pass, 20l/min, 24V/200A welder is good at making specimens with the quality shown in radiographic testing.

섬유강화플라스틱 사출성형 공정에서 기계적 성질에 관한 연구

백정환(Jung-Hwan Baek) 산업기술교육훈련학회 2012 산업기술연구논문지 (JITR) Vol.17 No.4

This study aims to examine the various phenomena occurring in the injection molding process for long fiber-reinforced polymeric composites and to establish a systematic research on such phenomena. The key results are as follows: (1) The mechanical properties of injection-molded long fiber-reinforced polymeric composites are more dominantly influenced by material factors such as fiber content in the composites than by molding conditions. (2) Fiber content increases up to 30wt%, but starts to decrease from over 50wt%.

고주파절제를 이용한 자율기능성갑상선결절의 치료

백정환 ( Jung Hwan Baek ),김윤숙 ( Yoon Suk Kim ),이덕기 ( Ducky Lee ) 대한갑상선학회 2008 International Journal of Thyroidology Vol.1 No.1

A 45-year-old female patient visited our thyroid center with thyrotoxic symptoms and bulging of left neck. Ultrasonogram showed a 3.1 cm sized solid thyroid nodule. The serum TSH level decreased (0.005 u/ml, normal range; 0.4∼4.0 u/ml), however the serum T3 and FT4 levels were within normal limit. 99mTc pertechnate scintigraphy showed a hot nodule in her left thyroid gland and suppression of the extra-nodular uptake. As she refused surgery and 131I radioiodine therapy, radiofrequency ablation was recommended. After two treatment sessions, the serum TSH level was normalized and hyperthyroid symptoms had resolved. At the 16-month follow-up, the hot nodule was invisible and the suppressed extra-nodular uptake had returned to normal. Radiofrequency ablation is a feasible minimally invasive modality for the treatment of an autonomously functioning thyroid nodule.

내용 : 교육소의 학생들을 대상으로 확률 이해수준에 관한 연구

백정환 ( Hwan Baek Jung ),고상숙 ( Sook Koh Sang ) 한국수학교육학회 2012 수학교육 Vol.51 No.3

Since research has barely been done on the minority with low-achievement & low-SES in probability, this research attempted to search the change of their thinking level in the classes of probability and motivate them on the mathematical learning to feel confident in mathematics. We can say that the problems of the educational discriminations are due to the overlook on the individual conditions, situations, and environments. Therefore, in order to resolve some discrimination, 4 students who belonged to the minority group, engaged in the research, based on 10 units of the instructional materials designed for the research. As a result, for the student`s thinking level, it was observed that they were improved from the 1st to the 3rd level in probability. Also, the researcher found that the adequate use of the encouragement, the praise, the direct explanation, and the scaffolding enabled them to prompt their learning motives and the increased responsibility on the learning. As time passed, the participants could share their mathematical knowledge and its concept with others, in the increased confidence.

Different perspectives for the management of big benign-looking thyroid nodule Perspectives from radiologist

백정환(Jung Hwan Baek) 대한갑상선-내분비외과학회 2016 대한갑상선-내분비외과학회 학술대회 논문집 Vol.- No.-

교육소외 학생들을 위한 수업모형과 통계이해수준에 관한 연구

백정환 ( Jung Hwan Baek ),고상숙 ( Sang Sook Koh ) 한국수학교육학회 2011 수학교육 Vol.50 No.3

We took note of the fact that there were not many studies on improvement of mathematics learning in the field of statistics for the minority students from the families who belonged to the Low-SES. This study was to help them understand the concepts and principles of mathematics, motivate them for mathematics learning, and have them feel familiar with it. The subjects were 12 students from the low-SES families among the sophomores of 00 High School in Gyeonggi-do. Although it could not be achieved effectively in the short-term of learning for the slow learners, their understanding of basic concepts and confidence, interests and concerns in statistical learning were remarkably changed, compared to their work in the beginning period. Our discourse classes using various topics and examples were well perceived by the students whose performance was improved up to the 3rd thinking level of Mooney`s framework. Also, a meaningful instructional model for slow learners(IMSL) was found through the discourse.

대한갑상선영상의학회 역사

나동규 ( Dong Gyu Na ),백정환 ( Jung Hwan Baek ) 대한갑상선학회 2018 International Journal of Thyroidology Vol.11 No.1

The Korean Society of Thyroid Radiology (KSThR) was founded as an affiliated subspecialty society of Korean Society of Radiology in 2010. The KSThR was originated from the thyroid radiology research committee which had started within the Korean Society of Neuroradiology in 2005. In the beginning, the research committee was organized to make a clinical guideline for ultrasonography (US) diagnosis and US-guided biopsy of thyroid nodules to cope with the rapidly increasing role of US imaging and the increasing burden of US-guided biopsy for thyroid nodules in the early 2000s. The KSThR proposed a subspecialty of thyroid radiology which is a medical subspecialty dealing with the imaging-based diagnosis and interventional treatment of thyroid disease. The KSThR has made an effort to make an advance in the research of thyroid imaging and intervention, which could provide scientific evidences for imaging-based management of nodular thyroid disease and thyroid cancers. The KSThR has published clinical guidelines of diagnostic imaging and interventional management of thyroid nodules, which included the US diagnosis and imaging-based management, fine-needle aspiration, core needle biopsy, and radiofrequency ablation therapy in thyroid nodules. The KSThR has a mission to play a leading role in the research and clinical practice of imaging-based management of thyroid disease, and the KSThR will make an advance in collaboration with Korean Thyroid Association.

금속 이온이 다중기포 Sonoluminescence 스펙트럼에 미치는 영향 연구

한문수,이제욱,백승찬,백정환,김영환,Han, Moon-Su,Lee, Jae-Wook,Baek, Seung-Chan,Baek, Jung-Hwan,Kim, Young-H. 한국음향학회 2010 韓國音響學會誌 Vol.29 No.2

본 연구에서는 액체 내에서 초음파에 의해 빛이 발생하는 현상인 Sono-Luminescence (이하 SL)에 대해 연구하였다. 알칼리 금속과 알칼리 토금속 화합물을 녹인 용액에서의 SL을 관찰 하였으며, 금속 이온 농도, 금속이온의 종류를 바꾸어 가며 SL에 미치는 영향을 조사하였다. 이 때 각각의 SL에서 나오는 빛을 사진으로 찍어 RGB 성분 분석을 통해 금속 이온을 녹인 용액의 SL이 증류수에서 SL과 금속 불꽃 반응 색 또는 선스펙트럼에서 강한 세기로 방출되는 색의 합성으로 표현될 수 있는지 연구하였다. 알칼리 금속의 경우 두 색의 합성으로 잘 표현되었으나 알칼리 토금속의 경우는 그렇지 않았다. 그 이유로 SL 방출시 온도가 그리 높지 않아서 알칼리 토금속의 선스펙트럼에서 에너지가 큰 단파장의 빛이 SL에서 잘 방출되지 않기 때문인 것으로 추론하였다. Sonoluminescence (SL) is the light emitting phenomenon accompanied with ultrasonic cavitation in liquid. It attracts many interests because physics behind it remains uncertain and few applications have appeared. It has been known that the color of SL changes in solutions which include metallic ions. In the present work, colors of SL in alkali metallic and alkaline earth metallic ions were considered. RGB component was used to analyze the color of SL. By using RGB component, it was found that color of SL in metallic solution can be resolved into color of SL in pure water and flame color of metal which is different from high intensity color of line spectrum of alkaline earth metal. From this result, influence of metallic ion on SL and the temperature on violent collapsing of cavitation bubble was discussed.

근거기반 임상진료지침 개발 협력 연구

최솔지(Sol Ji Choi),정승은(Seung Eun Jung),정우경(Woo Kyoung Jeong),최미영(Mi young Choi),백정환(Jung Hwan Baek) 한국보건의료연구원 2016 근거와 가치 Vol.2 No.3

Objectives: This study aims to establish collaboration system for trustworthy clinical practice guideline. Evidence- based Korean Clinical Imaging development was led by the Korean Society of Radiology (KSR) and the National Evidence-based Healthcare Collaborating Agency (NECA). Methods: Collaboration framework is consisted of internal collaboration and external collaboration. Guideline development committee and working groups co-worked as internal collaboration. As extra collaboration, expected end-users were involved in consensus group who are clinical experts related to guidelines. Protocol for guideline development and education was performed. Consensus group consulted during developing process and contributed to panel survey. Results: Collaborating works for trustworthy clinical practice guideline, a protocol was developed to reflect the process of developing diagnostic guidelines in Korea, which differs from traditional interventional treatment. Conclusion: Collaboration framework was effective for developing evidence-based clinical imaging guideline. Moreover, this framework will be continued and revised respond to the needs for trustworthy guidelines.