• 한국터널지하공간학회 논문집
• /
• 제25권6호
• /
• pp.479-493
• /
• 2023

터널과 공동구와 같은 지하구조물의 공용연수가 증가하고 노후화로 인한 사고로 인하여 안전 관리의 필요성이 대두되고 있다. 다만, 민간이 관리 주체인 일반 지하구의 경우 시설물 안전 및 유지관리 세부지침이 미흡하여 안전 관리가 부실한 상황이다. 또한 일반 지하구는 기본 설계 정보가 부족하고 안전 관리자가 안전 진단을 수행하기 위한 공간이 협소하여 기존 비파괴 검사법들의 적용에 한계가 있다. 따라서 본 연구에서는 박스형 일반 지하구의 안전 진단을 위한 기초 자료로 사용될 수 있는 구조물의 두께·철근 유무와 철근 깊이·내부 결함의 유무 및 깊이 등을 판단할 수 있는 품질 평가를 위한 초음파법과 충격 반향 기법 바탕의 비파괴 검사 방법을 제안하였다. 일반 지하구의 실제 현장 조건에서의 제안한 방법의 유효성을 검토하기 위해 콘크리트 벽체 모형 실험체들을 제작하여, 본 연구를 통해 제안한 방법론을 검증하였다. 초음파 신호와 충격 신호를 활용하여 신호를 인가하여, 다채널로 구성된 가속도계를 통해 신호를 수집하고, 최종적으로 모사된 시편의 두께 및 내부에 삽인 된 철근과 구현된 결함의 깊이를 도출하였으며, 실측치와의 비교를 통해 예측한 깊이가 설계한 깊이와 효과적으로 부합하는 것을 확인하였다. 본 연구 결과를 통해 일반 지하구 현장에서 활용할 수 있는 안전 진단 방법의 도출에 기여할 것으로 기대된다.

• 한국산업보건학회지
• /
• 제25권1호
• /
• pp.82-88
• /
• 2015

Objectives: This study is designed to analyze the penetration performance into ceiling materials containing asbestos of scattering prevention agents and investigate the change in penetration depth and viscosity according to the dilution rate of anti-scattering agents diluted with distilled water. Methods: Five different types of scattering prevention agents were spread on plate-type asbestos ceiling materials. The penetration depth of each coated ceiling material was measured by energy dispersive spectroscopy (EDS) analysis, based on X-ray fluorescence (XRF) results of the non-coated ceiling materials. Test equipment installed the ceiling materials and 60 minutes were collected at a flow rate of $10{\ell}/min$ at a filter of 25 mm. Results: An EDS analysis of the cross-section of ceiling materials constructed with a scattering prevention agent revealed that potassium is detected in the process of penetrating hardener solidification and this element could be an indicator for infiltration. When anti-scattering agents with different viscosities were constructed and the penetration depth was analyzed by potassium detection assessment using EDS, the depth results with viscosities of 5.0, 2.5, and 1.9 cP were 98.5, 103, and $147{\mu}m$, respectively. Penetration performance improved with decrease in viscosity. Conclusions: For asbestos ceiling materials, it is concluded that a higher dilution rate of the scattering prevention agent leads to lower viscosity, and hence a deeper penetration depth from $156{\mu}m$ to 3 mm. The asbestos anti-scattering properties according to the penetration depth will be confirmed through further study.

• Asian Pacific Journal of Cancer Prevention
• /
• 제13권5호
• /
• pp.2241-2247
• /
• 2012

Objective: This qualitative study retrospectively examined the experience and psychological impact of contralateral prophylactic mastectomy (CPM) among Southern Chinese females with unilateral breast cancer history who underwent BRCA1/2 genetic testing. Limited knowledge is available on this topic especially among Asians; therefore, the aim of this study was to acquire insight from Chinese females' subjective perspectives. Methods: A total of 12 semi-structured in-depth interviews, with 11 female BRCA1/BRCA 2 mutated gene carriers and 1 non-carrier with a history of one-sided breast cancer and genetic testing performed by the Hong Kong Hereditary Breast Cancer Family Registry, who subsequently underwent CPM, were assessed using thematic analysis and a Stage Conceptual Model. Breast cancer history, procedures conducted, cosmetic satisfaction, pain, body image and sexuality issues, and cancer risk perception were discussed. Retrieval of medical records using a prospective database was also performed. Results: All participants opted for prophylaxis due to their reservations concerning the efficacy of surveillance and worries of recurrent breast cancer risk. Most participants were satisfied with the overall results and their decision. One-fourth expressed different extents of regrets. Psychological relief and decreased breast cancer risk were stated as major benefits. Spouses' reactions and support were crucial for post-surgery sexual satisfaction and long-term adjustment. Conclusions: Our findings indicate that thorough education on cancer risk and realistic expectations of surgery outcomes are crucial for positive adjustment after CPM. Appropriate genetic counseling and pre-and post-surgery psychological counseling were necessary. This study adds valuable contextual insights into the experiences of living with breast cancer fear and the importance of involving spouses when counseling these patients.

• 한국방재안전학회논문집
• /
• 제15권4호
• /
• pp.11-20
• /
• 2022

국내의 앵커볼트 일반 비파괴 검사법은 육안검사와 타음검사를 적용하고 있으나, 육안검사는 기초에 포함된 부분이나 너트 및 베이스 플레이트가 설치된 부분에서 앵커볼트의 부식이나 피로균열 등을 확인하는 것이 어렵다. 타음검사는 주변 환경과 개인차에 의한 영향을 받기 때문에 객관적인 조사가 어려운 것이 현실이므로 이러한 결함을 정량적으로 추정할 수 있는 비파괴 검사 기술개발이 필요하다. 국내 도로시설물 앵커볼트의 점검은 육안조사를 수행하고 있으며, 교량받침, 낙교방지시설 등의 앵커볼트 중요도가 높으므로 기존 점검방법과 함께 비파괴검사 기술을 개발하여 앵커볼트의 예방정비를 통해 교량 수명연장에 기여할 필요가 있다. 본 기술 개발을 통해 현재 수행하고 있지 않은 앵커볼트의 비파괴검사를 수행함으로 도로시설물 앵커볼트의 선제적/능동적 유지관리가 가능한 기술로 연구개발 및 실용화가 시급하다. 본 논문에서는 비파괴 검사 기법 중 초음파탐상법(Ultrasonic test)을 적용하여 부식, 균열 등 앵커볼트의 결함 검출 가능성 및 실뢰도를 실험적으로 검증하였다. 기술 개발이 완성되면 검사 신뢰성 향상 원천기술 확보로 앵커볼트에 대한 선제적/능동적 유지관리의 실현이 가능할 것으로 기대된다.

• The Journal of Advanced Prosthodontics
• /
• 제6권5호
• /
• pp.351-360
• /
• 2014

PURPOSE. The aim of present study was to identify characteristic and response of mouse bone marrow (BM) derived low-adherent bone marrow mesenchymal stem cells (BMMSCs) obtained by quantification of extracellular matrix (ECM). MATERIALS AND METHODS. Non-adherent cells acquired by ECM coated dishes were termed low-adherent BMMSCs and these cells were analyzed by in vitro and in vivo methods, including colony forming unit fibroblast (CFU-f), bromodeoxyuridine (BrdU), multi-potential differentiation, flow cytometry and transplantation into nude mouse to measure the bone formation ability of these low-adherent BMMSCs. Titanium (Ti) discs with machined and anodized surfaces were prepared. Adherent and low-adherent BMMSCs were cultured on the Ti discs for testing their proliferation. RESULTS. The amount of CFU-f cells was significantly higher when non-adherent cells were cultured on ECM coated dishes, which was made by 7 days culturing of adherent BMMSCs. Low-adherent BMMSCs had proliferation and differentiation potential as adherent BMMSCs in vitro. The mean amount bone formation of adherent and low-adherent BMMSCs was also investigated in vivo. There was higher cell proliferation appearance in adherent and low-adherent BMMSCs seeded on anodized Ti discs than machined Ti discs by time. CONCLUSION. Low-adherent BMMSCs acquired by ECM from non-adherent cell populations maintained potential characteristic similar to those of the adherent BMMSCs and therefore could be used effectively as adherent BMMSCs in clinic.

• 한국생산제조학회지
• /
• 제25권1호
• /
• pp.48-53
• /
• 2016

An EMAT can be used to reliably detect defects as it serves as a non-contact transducer with the ability to transmit ultrasonic waves into specimens without couplant. Moreover, an EMAT can easily generate desired waves by altering the design of the coil and magnet. This study proposes an SH-EMAT to evaluate the integrity of the TIG welding part. A stainless steel was welded using the TIG welding method. The welding current was varied to create artificial defects. Both the PA-UT and the RT were applied to verify the defect size. The experimental results generated by using the EMAT were compared with those methods. The amplitude was observed to decrease with an increase in the defect size. These results confirmed that the presence of defects can be reliably detected by attenuation of signal amplitude. The results demonstrated that the proposed method is suitable for evaluating the integrity of TIG welding.

• The Journal of Korean Physical Therapy
• /
• 제25권4호
• /
• pp.180-186
• /
• 2013

Purpose: This study was to find a correlation between the bilateral reciprocal leg press test and a the balance in chronic stroke patients. Methods: Eighteen patients performed an isokinetic leg press test consisting of a bilateral reciprocal and unilateral mode. Following the isokinetic leg press testing, subjects performed the balance test: Berg Balance Scale (BBS), Timed Up & Go (TUG) test, and stability limit. Pearson product moment correlation coefficients were used to determine the correlation between the mean score of the isokinetic leg press test, balance test in both affected and non-affected side. Results: This study indicated a significant correlation between the bilateral reciprocal leg press test and stability limit. There were significant correlation between non-affected side bilateral leg press(NBL) and BBS (r=0.501), affected side bilateral leg press (ABL) and non-affected side stability limit(NS) (r=0.614), ABL and total stability limit (TS) (r=0.493), NBL and affected side stability limit(AS) (r=0.480), NBL and NS (r=0.560), NBL and TS (r=0.563), among the patients. Conclusion: Measurement of the lower extremity strength using the bilateral reciprocal leg press test can be used as an evaluating tool of the balance test.

• 한국산업보건학회지
• /
• 제24권3호
• /
• pp.365-370
• /
• 2014

Objectives: The major objective is development of an eco-friendly non-phthalate plasticizer using crude glycol derived from the biodiesel process. Methods: Glycerol monolaurate(GML) was synthesized from glycol and triglyrcerides. Glycerol diacetomonolaurate(GDAL) was synthesized from GML and acetic acid. Results: The synthesis of the GDAL plasticizer was measured with nuclear magnetic resonance spectroscopy(NMR). Mechanical properties were measured by universal testing machine(UTM) and the experimental values were compared with phthalate plasticizers such as dioctyl phthalate(DOP). In particular, the values for tensile strength and elongations with GDAL were higher than with DOP. Conclusions: We confirmed the development of an eco-friendly non-phthalate plasticizer by NMR. Based on our results, applicability for food and drug packaging materials was found.

• Computers and Concrete
• /
• 제34권1호
• /
• pp.15-31
• /
• 2024

This study explores the failure mechanisms of 'I' shaped non-persistent cracks under uniaxial loads through a combination of experimental tests and numerical simulations. Concrete specimens measuring 200 mm×200 mm×50 mm were manufactured, featuring 'I' shaped non-persistent joints. The number of these joints varied from one to three, with angles set at 0, 30, 60, and 90 degrees. Twelve configurations, differing in the placement of pre-existing joints, were considered, where larger joints measured 80 mm in length and smaller cracks persisted for 20 mm with a 1 mm crack opening. Numerical models were developed for the 12 specimens, and loading in Y-axis direction was 0.05 mm/min, considering a concrete tensile strength of 5 MPa. Results reveal that crack starting was primarily influenced by the slope of joint that lacks persistence in relation to the loading direction and the number of joints. The compressive strength of the samples exhibited variations based on joint layout and failure mode. The study reveals a correlation between the failure behavior of joints and the number of induced tensile fracture, which increased with higher joint angles. Specimen strength increased with decreasing joint angles and numbers. The strength and failure processes exhibited similarities in both laboratory testing and numerical modeling methods.

• 비파괴검사학회지
• /
• 제29권5호
• /
• pp.485-492
• /
• 2009

열피로균열은 원자력발전소의 운영 과정에서 구조물의 수명을 결정짓는 문제로 정량적인 탐지가 어렵다. 현재 산업현장에서 구조물에 대한 건전성을 정량적으로 평가하기 위해서 radiographic탐상 및 초음파탐상, eddy current 등 다양한 종류의 비파괴검사 기술이 사용되고 있지만, 위에 열거한 비파괴탐상법의 경우 균열이 일정부분 진행된 이후에나 검출이 가능하다는 제한 사항이 있다. 이러한 이유로 구조물에 대한 연속적인 모니터링이 가능한 장점을 가진 음향방출탐상법(acoustic emission testing)이 대안적인 검사방법으로 제시되고 있다. 일반적으로 구조물이나 장비의 건전성에 영향을 미치는 모든 요인들이 음향방출 신호의 발생을 일으키기 때문에, 음향방출을 이용한 결함 탐상시 함께 발생하는 노이즈를 구분하는 일은 음향방출을 연구하는 대부분의 연구원의 주요 업무중 하나라고 할 수 있다. 이에 본 연구에서는 열피로 사이클 조건에서의 배관에 대한 음향방출 신호를 수집하여 유효한 균열 신호를 노이즈로부터 구분하고자 하는 목적으로 진행되었다. 그 방법으로 유사한 조건에서 실시한 결과를 이용하여 노이즈 필터링 조건을 설정하였으며, 균열의 신호를 찾아내기 위한 방법으로 음향파형(waveform) 구분법을 제시하였다. 이 실험에서 도출된 결과는 구조물의 결함을 탐지하는 실시간 연속적 모니터링 기술 개발에 대한 기초자료로 사용될 수 있을 것으로 기대된다.