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박가현,정영훈 대한토목학회 2020 KSCE Journal of Civil Engineering Vol.24 No.1
This paper explains a newly developed technique for identifying particles belonging to the contact force chains in a model particle assembly. This was accomplished through digital image analysis of the color images obtained from photoelastic measurements. Descriptive statistics for RGB color intensities of pixels in a central square region inside the particle were digitally measured to determine the particle force, as opposed to the traditional method of counting fringe orders. The relationships between the descriptive statistics of the RGB color intensities and the applied forces were analyzed. The developed image analysis technique was applied to digital photoelastic images of an assembly of stacked particles. This technique could embed the numeric data of the particle forces in the digital photoelastic images which provide comprehensive information for a quantitative analysis of the progressive evolution of the soil arching phenomena in a particulate media.
박가현,김덕규,허윤현,이규석,이수현,홍윤경,김선헌,국민석,고정태,전장수,이시은,류제황 생화학분자생물학회 2017 Experimental and molecular medicine Vol.49 No.-
Periodontal disease is one of the most prevalent chronic disorders worldwide. It is accompanied by inflammation of the gingiva and destruction of periodontal tissues, leading to alveolar bone loss. Here, we focused on the role of adipokines, which are locally expressed by periodontal tissues, in the regulation of catabolic gene expression leading to periodontal inflammation. The expression of the nicotinamide phosphoribosyltransferase (NAMPT) adipokine was dramatically increased in inflamed human and mouse gingival tissues. NAMPT expression was also increased in lipopolysaccharide- and proinflammatory cytokine-stimulated primary cultured human gingival fibroblasts (GF). Adenovirus-mediated NAMPT (Ad-Nampt) overexpression upregulated the expression and activity of COX-2, MMP1 and MMP3 in human GF. The upregulation of IL-1β- or Ad-Nampt-induced catabolic factors was significantly abrogated by the intracellular NAMPT (iNAMPT) inhibitor, FK866 or by the sirtuin (SIRT) inhibitor, nicotinamide (NIC). Recombinant NAMPT protein or extracellular NAMPT (eNAMPT) inhibition using a blocking antibody did not alter NAMPT target gene expression levels. Moreover, intragingival Ad-Nampt injection mediated periodontitis-like phenotypes including alveolar bone loss in mice. SIRT2, a part of the SIRT family, was positively associated with NAMPT actions in human GF. Furthermore, in vivo inhibition of the NAMPT-NAD+-SIRT axis by NIC injection in mice ameliorated the periodontal inflammation and alveolar bone erosion caused by intragingival injection of Ad-Nampt. Our findings indicate that NAMPT is highly upregulated in human GF, while its enzymatic activity acts as a crucial mediator of periodontal inflammation and alveolar bone destruction via regulation of COX-2, MMP1, and MMP3 levels.
박가현,박홍주,곽희붕,이여진,문원진 대한이비인후과학회 2008 대한이비인후과학회지 두경부외과학 Vol.51 No.8
The superior canal dehiscence syndrome (SCDS) is a rare disorder caused by the dehiscence of the temporal bone overlying the superior semicircular canal. It has become apparent that SCDS can lead to a variety of clinical manifestations, vestibular and/or auditory, in contrast to the typical symptoms, as initially described. We recently examined a 54-year-old woman with unilateral stepsynchronous tinnitus without any vestibular symptoms. Tinnitus is a quite unremarkable finding among variable symptoms of the syndrome; however, it can be one of the clues to identify SCDS when it is accompanied by low-frequency conductive hearing loss. Therefore, in diagnosing SCDS, attention must be also paid to those patients with nonspecific complaints, for example, stepsynchronous tinnitus. (Korean J Otorhinolaryngol-Head Neck Surg 2008;51:738-41)
박가현,김시형,이동훈 한국건강심리학회 2020 한국심리학회지 건강 Vol.25 No.1
The purpose of this study was to examine the validity and the reliability of a Korean Version of the Beliefs About Emotions Scale(BES-K). The BES(Rimes & Chalder, 2010) is a self-report questionnaire used to measure the beliefs about experiencing and expressing negative emotions. For this study, 1,137 Korean adults participated in the survey. Four steps of the EFA-SEM procedures were applied to identify the factor structure of the BES-K. The results showed three-factor constructs(relational beliefs, intrapersonal beliefs, and conventional beliefs). Also, the BES-K factors showed adequate internal consistency and correlations. The BES-K factors were positively correlated with emotional dysregulation, anxiety, depression, and somatization, supporting good concurrent validity. In conclusion, the BES-K was found to be a valid instrument measuring the beliefs about emotions of the Korean population. 본 연구는 정서에 대한 부정적 신념을 측정하는 정서에 대한 신념 척도를 타당화하고자 하였다. 이를 위해 성인 1,137명을 대상으로 정서에 대한 신념 척도의 요인구조를 확인하고 신뢰도와 타당도를 검증하였다. 먼저, 이순묵 등(2016)이 제시한 EFA-SEM의 4단계 절차를 따라 요인구조를 확인하였다. 이 절차는 요인 분석 가능성 검토 및 요인수효 결정, 탐색적 회전, 부분제약 목표회전, 측정오차 간 상관 추정으로 구성되어있다. 분석 결과, 정서에 대한 신념 척도는 3개의 요인(관계적 신념, 개인내적 신념, 통념적 신념)으로 구성되는 것을 확인하였다. 다음으로, 신뢰도를 확인하기 위해 내적 신뢰도를 검토하였으며 타당도를 확인하기 위해 유사한 개념을 측정하는 정서조절곤란 척도와 상관이 확인된 우울, 불안, 신체화 척도와의 상관분석을 실시하였다. 분석결과, 내적 신뢰도는 우수한 것으로 확인되었으며 BES-K는 정서조절곤란, 우울, 불안, 신체화와 정적 상관을 갖는 것으로 확인되었다. 이러한 연구결과에 기반 하여 본 연구의 논의와 시사점을 제시하였다.
깊이별 지반특성변화가 강우침투에 의한 사면표층 파괴에 미치는 영향
박가현,김지영,정충기,김경석 한국지반공학회 2014 한국지반공학회논문집 Vol.30 No.6
Intensive rainfall causes frequent slope failures at the shallow depths of slopes. Because soil layers at shallow depthsof slopes usually become dense, and its permeability and soil strength vary according to depth, forensic studies andstability analyses of shallow slope failure need to consider the depth-variant soil properties. In this study, the effectof depth-variant soil properties on surface failure of slopes during rain infiltration is investigated using numericalanalysis. Three different cases considering depth-variant soil properties were conducted and the results were compared. For the analysis, undisturbed soils at three different depths were sampled at actual slope failure sites and the propertiesincluding strength and permeability characteristics at each depth were obtained. Stability analysis and seepage analysiswere conducted using actual rainfall records. The comparison of the results shows that analysis could lead to anerroneous conclusion according to the way of considering depth-variant soil properties. The case in which depth-variantsoil properties were considered predicted similar failure times and failure shapes to the actual failure. Therefore itis recommended that the depth-variant soil properties should be considered for the analysis of shallow slope failureduring rain infiltration.
Evolution of Stiffness Anisotropy during Creep of Engineered Silty Sand in South Korea
박가현,정영훈,정충기 대한토목학회 2017 KSCE Journal of Civil Engineering Vol.21 No.6
The variation in elastic shear moduli measured through bender element tests and the nonlinear strains in the axial and radial directions of triaxial specimens during creep were experimentally investigated. To consider various conditions of different relative densities and different stress ratios, a number of triaxial specimens were prepared. The engineered silty sand reconstituted from weathered residual soil in South Korea was used as the testing material. Due to aging, the post-creep stress-strain curve exhibited a stiffer response compared to the pre-creep stress-strain curve. It was found that the variation in elastic shear stiffness and the nonlinear deformation during creep depends on the stress ratio and initial relative density. The continuous change in the stiffness anisotropy during creep was closely related to the creep deformation patterns.