Predicting Damage in a Concrete Structure Using Acoustic Emission and Electrical Resistivity for a Low and Intermediate Level Nuclear Waste Repository

Hong, Chang-Ho,Kim, Jin-Seop,Lee, Hang-Lo,Cho, Dong-Keun Korean Radioactive Waste Society 2021 방사성폐기물학회지 Vol.19 No.2

In this study, the well-known non-destructive acoustic emission (AE) and electrical resistivity methods were employed to predict quantitative damage in the silo structure of the Wolsong Low and Intermediate Level Radioactive Waste Disposal Center (WLDC), Gyeongju, South Korea. Brazilian tensile test was conducted with a fully saturated specimen with a composition identical to that of the WLDC silo concrete. Bi-axial strain gauges, AE sensors, and electrodes were attached to the surface of the specimen to monitor changes. Both the AE hit and electrical resistance values helped in the anticipation of imminent specimen failure, which was further confirmed using a strain gauge. The quantitative damage (or damage variable) was defined according to the AE hits and electrical resistance and analyzed with stress ratio variations. Approximately 75% of the damage occurred when the stress ratio exceeded 0.5. Quantitative damage from AE hits and electrical resistance showed a good correlation (R = 0.988, RMSE = 0.044). This implies that AE and electrical resistivity can be complementarily used for damage assessment of the structure. In future, damage to dry and heated specimens will be examined using AE hits and electrical resistance, and the results will be compared with those from this study.

수로교 손상 메커니즘 분석에 의한 보수설계 방법

변항용(Byun Hang-Yong),이수곤(Lee Soo Gon),송창영(Song Chang Young) 한국구조물진단유지관리학회 2004 한국구조물진단학회 학술발표회논문집 Vol.- No.-

수로교는 각각 독립된 U 자형의 수로와 교각이 받침 빛 신축이음 재료인 기능장치에 의하여 상ㆍ하 및 수평 연결된 철근콘크리트 구조물이다 이들 수로교는 설계도서상에서는 구조내력 부족 등 경항이 없고, 사용된 재료나 기술 및 시공된 후의 환경상태 동 모든 조건이 동일함에 도 균열, 붕피 퉁 구조안전을 위협하는 하자가 일정간격으로 반복되는 경우가 흔히 있다. 하자 보수 후 재 손상의 발생은 물론 보수 전 양호하였던 인접교각에까지 손상이 확대되어감이 일반 적이다 또한 이들 하자는 보수를 하지 않고 장기간 방치된 경우에는 손상이 확대되었고, 철거 후 재시공된 곳에서도 손상이 반복되는 양상을 보인다. 백년 이상의 내구성을 갖는다는 철근콘크리트조 수로교가 불과 수년경과 후 발생될 수밖에 없었던 손상은 구조적인 결함 때문이 아니라 받침장치의 부식 및 신축유격의 부족 등 기능장치의 결함으로「대기온도변화에 의한 수로의 길이방향 신ㆍ축 변형의 누적」이라는 손상 mechanism 의 결과 때문이다. 따라서 원인과는 무관하게 통상적인 방법으로, 바꾸어 말하면 근 본적인 원인의 규명 없이 이루어진 보수이기 때문에 재 손상 및 손상의 확산은 필연적이었다. 따라서 수로교의 보수설계는 수로에서 길이방향 변형 량의 누적현상이 일어나지 않도록 설계 및 시공되어야 수로교의 안천은 물론 내구성의 확보도 가능하게 된다. In elevated irrigation aquaducts, one can observe a common damage pattern. That is, cracks, and crushing of concrete are usually repeated at a certain interval even if no faults are found in the design and construction of the structures. To investigate the causes of this damage, longitudinal deformations of several aquaducts have been measured. The analysis of the measured data suggests that the damages are mainly caused by cumulative repetition of extension and contraction due to temperature changes.

Lipid Profile Change after Thyroidectomy

Chih Hao Chu,Soo Young Kim,Yong Sang Lee,Hang-Seok Chang 대한갑상선-내분비외과학회 2020 The Koreran journal of Endocrine Surgery Vol.20 No.3

Purpose: Thyroid diseases and lipid metabolic abnormalities have been reported to be correlated. In patients with thyroid cancer, thyroid stimulating hormone levels are suppressed to prevent recurrence. Many studies have reported dyslipidemia associated with thyroid function, although its extent before and after thyroidectomy remains to be studied. This study aimed to determine the lipid levels for administering accurate lipid treatment in thyroid cancer patients post thyroidectomy. Methods: In total, 1,203 patients with thyroid cancer who underwent thyroidectomy between June 1, 2016 and December 31, 2016 at the Thyroid Cancer Center, Gangnam Severance Hospital, Yonsei University, were enrolled in the study. Of these, patients aged <19 years and taking medication for dyslipidemia were excluded. Finally, we enrolled 295 thyroid cancer patients who underwent thyroidectomy and whose lipid profiles were confirmed pre- and post-operatively. Results: The total cholesterol levels in the lobectomy group without levothyroxine supplementation were significantly increased 1 year after surgery than those before surgery (168.17±29.19 mg/dL vs. 182.50±34.03 mg/dL, P=0.003). Additionally, the triglyceride (TG) levels were significantly decreased in the lobectomy with levothyroxine supplementation and total thyroidectomy groups, whereas cholesterol and low-density lipoprotein-cholesterol (LDL-C) levels showed no significant change. No significant changes in the levels of cholesterol, LDL-C, and TG were observed in all the 3 groups. Conclusion: Extent of surgery and levothyroxine supplementation had an insignificant impact on the levels of cholesterol, LDL-C, TG, and high-density lipoprotein-cholesterol compared pre- and post-operatively.

수로교 손상 메커니즘 분석에 의한 보수설계 방법

변항용 ( Byun Hang-yong ),이수곤 ( Lee Soo Gon ),송창영 ( Song Chang Young ) 한국구조물진단유지관리공학회 2004 한국구조물진단유지관리공학회 학술발표대회 논문집 Vol.8 No.2

수로교는 각각 독립된 U자형의 수로와 교각이 받침 및 신축이음 재료인 기능장치에 의하여 상·하 및 수평 연결된 철근콘크리트 구조물이다. 이들 수로교는 설계도서상에서는 구조내력 부족 등 결함이 없고, 사용된 재료나 기술 및 시공된 후의 환경상태 등 모든 조건이 동일함에도 균열, 붕괴 등 구조안전을 위협하는 하자가 일정간격으로 반복되는 경우가 흔히 있다. 하자 보수 후 재 손상의 발생은 물론 보수 전 양호하였던 인접교각에까지 손상이 확대되어감이 일반적이다. 또한 이들 하자는 보수를 하지 않고 장기간 방치된 경우에는 손상이 확대되었고, 철거 후 재시공된 곳에서도 손상이 반복되는 양상을 보인다. 백년 이상의 내구성을 갖는다는 철근콘크리트조 수로교가 불과 수년경과 후 발생될 수밖에 없었던 손상은 구조적인 결함 때문이 아니라 받침장치의 부식 및 신축유격의 부족 등 기능장치의 결함으로「대기온도변화에 의한 수로의 길이방향 신·축 변형의 누적」이라는 손상 mechanism의 결과 때문이다. 따라서 원인과는 무관하게 통상적인 방법으로, 바꾸어 말하면 근본적인 원인의 규명 없이 이루어진 보수이기 때문에 재 손상 및 손상의 확산은 필연적이었다. 따라서 수로교의 보수설계는 수로에서 길이방향 변형 량의 누적현상이 일어나지 않도록 설계 및 시공되어야 수로교의 안전은 물론 내구성의 확보도 가능하게 된다. In elevated irrigation aquaducts, one can observe a common damage pattern. That is, cracks, and crushing of concrete are usually repeated at a certain interval even if no faults are found in the design and construction of the structures. To investigate the causes of this damage, longitudinal deformations of several aquaducts have been measured. The analysis of the measured data Suggests that the damages are mainly caused by cumulative repetition of extension and contraction due to temperature changes.

4분과 : 미래 기후변화 시나리오에 따른 우리나라 소나무 임부의 재적 추정

김문일 ( Moon Il Kim ),이우균 ( Woo Kyun Lee ),( Gui Shan Gui ),( Hang Nan Yu ),최솔이 ( Sol E Choi ),김창길 ( Chang Gil Kim ),권태성 한국임학회 2014 한국산림과학회지 Vol.103 No.1

본 연구는 우리나라 주요 수종인 소나무림을 대상으로 RCP(Representative Concentration Pathway)8.5 시나리오에 따른 임목 재적의 시·공간적 변이를 예측하기 위해 수행되었다. 전국 규모의 예측을 위해 5차임상도와 국가산림자원조사 자료를 이용하였으며, 기후와 공간의 변이가 임목 생장에 미치는 영향을 반영하기 위해 기상 및 지형인자를 반영한 생장모형을 적용하였다. 모형의 검증을 위해 시, 도별 산림통계와 모형 결과를 비교한 결과, 비교적 높은 적합도를 보이는 것으로 나타났다. 기후변화를 고려하였을 때, 소나무림의 임분 재적은 현재 131 m3/ha에서2050년에는 212.42 m3/ha까지 증가 할 것으로 예측되었으며, 현재의 기후가 유지될 경우에는 221.92 m3/ha까지 증가할 것으로 예측되었다. 기후변화의 영향으로 인해 일부 고산지대를 제외한 대부분의 지역에서 소나무림의 생장률이감소할 것으로 예측되었으며, 특히 해안지역과 남부지역에서 생장률의 감소가 클 것으로 나타났다. 본 연구결과를 통해 기후변화가 소나무림 생장에 미치는 영향을 시·공간에 따라 정량화 할 수 있었으며, 이는 기후변화 적응을 고려한 산림관리 및 시업계획을 수립하는데 유용하게 활용될 수 있을 것이다. The main purpose of this study is to measure spatio-temporal variation of forest tree volume basedon the RCP(Representative Concentration Pathway) 8.5 scenario, targeting on Pinus densiflora forests which is the main tree species in South Korea. To estimate nationwide scale, 5th forest type map and National Forest Inventory data were used. Also, to reflect the impact of change in place and climate on growth of forest trees, growth model reflecting the climate and topography features were applied. The result of the model validation, which compared the result of the model with the forest statistics of different cities and provinces, showed a high suitability. Considering the continuous climate change, volume of Pinus densiflora forest is predicted to increase from 131 m3/ha at present to 212.42 m3/ha in the year of 2050. If the climate maintains as the present, volumeis predicted to increase to 221.92 m3/ha. With the climate change, it is predicted that most of the region, except for some of the alpine region, will have a decrease in growth rate of Pinus densiflora forest. The growth rate of Pinus densiflora forest will have a greater decline, especially in the coastal area and the southern area. With the result of this study, it will be possible to quantify the effect of climate change on the growth of Pinusdensiflora forest according to spatio-temporal is possible. The result of the study can be useful in establishing the forest management practices, considering the adaptation of climate change.

수술 전 이하선 종괴의 위치파악에 이용하는 해부학적 경계표의 유용도

임치영(Chi Young Lim),김국진(Kook Jin Kim),임성주(Sung Ju Lim),이잔디(Jan dee Lee),남기현(Kee Hyun Nam),장항석(Hang Seok Chang),정웅윤(Woong Youn Chung),최홍식(Hong Shik Choi),박정수(Cheong Soo Park) 대한두경부종양학회 2006 대한두경부 종양학회지 Vol.22 No.1

Background: The location of parotid gland tumors can influence the duration and the difficulty of the operation. If the information about tumor location was available preoperatively, it would allow accurate operative planning and counseling of patients in terms of the length of the operation and the potential morbidity. Methods: This study was based on a retrospective review of 100 patients with parotid gland tumors underwent parotidectomy from January 2000 to October 2005 at Yong-Dong Severance Hospital. Based on computed tomographic(CT) scan findings, 4 landmarks such as facial nerve(FN) line, Utrecht(U) line, Conn's are(CA), and retromandibular vein (RV) were drawn on the scans in same plane. The location of tumors were determined by the landmarks and confirmed by the operative findings. The accuracy of each landmarks was evaluated. To find out the accuracies according to tumor size, the tumors were divided into 2 groups; less than 2 cm and larger than 2 cm in diameter. Results: U line was the most accurate(94%), sensitive(89.3%) and specific(97.7%) in predicting tumor location of the parotid gland. However, in small tumors less than 2cm, FN line (p=0.022) and RV criteria (p=0.028) were more reliable in accuracy. Conclusion: CA, FN line, U line, and RV are all useful landmarks in preoperative prediction for the location of parotid gland tumors. However, U line was the most accurate, but we must consider that proper landmark should be used in prediction according to the size of tumor because the accuracy of landmark may change.

LED light for in vitro and ex vitro efficient growth of economically important highbush blueberry (Vaccinium corymbosum L.)

Hung, Cao Dinh,Hong, Chang-Hee,Kim, Seon-Ki,Lee, Kyu-Han,Park, Jea-Young,Nam, Min-Woo,Choi, Dae-Ho,Lee, Hye-In Springer-Verlag 2016 ACTA PHYSIOLOGIAE PLANTARUM Vol.38 No.6

Online Phase Tracking of Interferometric Optical Fiber Sensors for Vibration Control

Chang, Young-Hwan,Kim, Do-Hyung,Han, Jae-Hung,Lee, IN Sage Science Press (UK) 2007 Journal of intelligent material systems and struct Vol.18 No.4

<P>Online phase tracking of an extrinsic FabryU2014;Perot interferometer (EFPI) and experimental vibration control of a composite beam with a sensing patch are investigated. EFPI sensors have nonlinearity due to their interferometric characteristics. We propose a new sensing patch for compensation of this interferometric nonlinearity. This newly developed sensing patch consists of an EFPI sensor and another sensor that can produce directional information. Therefore, it uses the advantages of their components used in conjuction in order to overcome the disadvantages of the components used separately. A sensing patch that comprises an EFPI sensor and a piezoceramic is fabricated, and the characteristics are experimentally investigated. A simple and practical logic is applied to real-time tracking of the optical phase of an interferometer. The experimental results show that the proposed sensing patch does not suffer from the nonlinear behavior of conventional EFPI sensors and the hysteretic behavior of piezoelectric materials. Moreover, it has excellent strain resolution and a wide dynamic sensing range. The application of a sensing patch has been also investigated: vibration control with this sensing patch has been performed using a fuzzy logic controller (FLC), and the possibility of using a sensing patch as a sensoriactuator is considered.</P>

Concurrent Primary Carcinoma and Metastatic Lesions of the Thyroid

Lee Jun Sung,Lee Jin Seok,Yun Hyeok Jun,Lee Yong Sang,Chang Hang-Seok 대한내분비외과학회 2022 The Koreran journal of Endocrine Surgery Vol.22 No.4

The thyroid gland is an infrequent site of metastases from other primary sites. Furthermore, concurrent primary carcinoma and metastatic disease of the thyroid gland is extremely rare. We report a case of concurrent primary and metastatic carcinoma of the thyroid gland.

Government Ownership and Corporate Social Responsibility Information Disclosure : Evidence from Viet Nam

Hang Thi Thuy Pham,Sung-Chang Jung,Su-Yol Lee 한국재무학회 2019 한국재무학회 학술대회 Vol.2019 No.05

In this paper, we examine the impact of government ownership on Corporate Social Responsibility disclosure in case of Viet Nam in period 2010 – 2016. This paper uses a sample of 374 listed firms in Ho Chi Minh Stock Exchange (HOSE) and Ha Noi Stock Exchange (HNX) excluding the financial sector. The findings highly support the institutional theory which implies that the ownership concentration characteristic affects negatively the level of CSR disclosure. Since the special feature of the Vietnamese economy, government ownership might be in line with the ownership concentration. We find strong and robust evidence that government ownership has a negative impact on CSR information disclosure. In addition, consistent with the previous research, size, profitability and firm’s age are positively related to CSR disclosure, and leverage is negatively associated with CSR disclosure.