Electric doors have been applied in urban trains since 2007 and operated for a long time. Recently, the failure of mechanical devices in electric doors have been increasing. The door is a device that is directly related to the safety of passengers. The rivet breakage of a ball/nut assembly may occur to an accident during train operation. In this study, the operating voltage and acceleration data of the door were collected for rivet condition monitoring, and 4 features were extracted in the frequency domain using the acceleration data. The classification performance of the rivet condition according to the axial direction of the acceleration data and 4 kernel functions was evaluated using SVM algorithm. When the X-axis data and Gaussian kernel function were used, the highest classification performance was shown for the electric door’s rivet with 90% accuracy.

본 연구에서는 2008년 1월부터 2019년 10월까지 보고된 국내외 출간･비출간 연구를 대상으로 오락용 게임이 일반 사용자의 공격성, 사회성 및 정서에 미치는 영향에 대한 다변량 메타분석을 시행했다. 총 22개 관련 연구(효과 크기 수 = 54개, 참여자 수 = 8031명)에 대한 메타분석 결과에 따르면, 게임의 폭력성 또는 폭력적 게임의 이용이 사용자의 정서기능에 미치는 영향은 크지 않았다. 진실험연구 분석 결과에서만 게임의 폭력성 또는 폭력적 게임의 이용이 사용자 의 공격적 인지와 친사회적 행동에 약한 수준의 부정적 영향을 미치는 것으로 나타났다. 뿐만 아니라 공격적 행동과 부정적 감정(예를 들면 불안, 우울 등)에 미치는 영향은 진실험, 준실험 및 상관회귀 연구 모두 통계적으로 유의미하지 않았다. 조절변수에 대한 메타분석 결과, 게임의 폭력성 또는 폭력적 게임 이용의 효과는 아동보다 청장년에게서, 남녀의 비율이 균등하게 통제된 연구보다 남성의 비율이 더 높은 연구에서, 그리고 방법론적 질이 높은 연구보다 방법론적 질이 낮은 연구에서 더 크게 나타났다. 본 연구의 결과는 게임의 폭력성 또는 폭력적 게임 이용이 사용자의 공격성에 미치는 영향은 크지 않으며, 이 또한 사용자의 연령과 성별 그리고 연구의 방법론적 질에 따라 좌우될 수 있음을 시사한다.

The relationship the between electrical properties and surface roughness (Ra) of a wet-etched silicon wafer were studied. Ra was measured by an alpha-step process and atomic force microscopy (AFM) while varying the measuring range 10×10, 40×40, and 1000×1000μm. The resistivity was measured by assessing the surface resistance using a four-point probe method. The relationship between the resistivity and Ra was explained in terms of the surface roughness. The minimum error value between the experimental and theoretical resistivities was 4.23% when the Ra was in a range of 10×10μm according to AFM measurement. The maximum error value was 14.09% when the Ra was in a range of 40×40μm according to AFM measurement. Thus, the resistivity could be estimated when the Ra was in a narrow range.

The electrical properties and surface morphology changes of a silicon wafer as a function of the HF concentration as the wafer is etched were studied. The HF concentrations were 28, 30, 32, 34, and 36 wt%. The surface morphology changes of the silicon wafer were measured by an SEM (80˚ tilted at ×200) and the resistivity was measured by assessing the surface resistance using a four-point probe method. The etching rate increased as the HF concentration increased. The maximum etching rate 27.31 μm/min was achieved at an HF concentration of 36 wt%. A concave wave formed on the wafer after the wet etching process. The size of the wave was largest and the resistivity reached 7.54 ohm·cm at an 30 wt% of HF concentration. At an HF concentration of 30 wt%, therefore, a silicon wafer should have good joining strength with a metal backing as well as good electrical properties.

This research tested how the perceived risk and the trust affect the usage intention of the cloud computing. To this end, this research setups a research model and tests it with the statistic tools. In order to build the model, TAM (Technology Acceptance

  The purpose of this study is to identify the factors determining users" acceptance of individualized virtual community. While there has been considerable research on the Technology Acceptance Model (TAM) that has predicted whether individuals will accep

  The purpose of this study is to identify the factors affecting intention to use blog. For this end, the individual characteristics (Subject Norm, Perceived Enjoyment, and Self-Efficacy) and the variables used in TAM (Perceived Ease of Use, and Perceived

The purpose of this study is to identify the factors affecting intention to use blog. Especially, The factors such as subject norm, perceived enjoyment, self-efficacy are individual characteristics to identify in this study. Also, Technology Acceptance Model(TAM) that has been widely used to predict the end-user's acceptance of a new technology is adopted for the study. A model with individual characteristics (subject norm, perceived enjoyment, and self-efficacy) and Technology Acceptance Model variables (perceived ease of use, and perceived usefulness) were used to explain intention to use blog. The suggested model has been empirically tested with questionaries. The result shows that individual characteristics such as perceived enjoyment and self-efficacy and factors of technology acceptance model have significant impact on users' intention using blog.

Recently, there is the trend that online and reuse have been focused via digitalization of information and business proc-ess that individuals, government and firms own This study, by designing and Implementing a system, has the arm to pro-vide on-line inf

최근 들어 지구온난화 등의 환경적요인 및 지역별 온도차 등으로 인한 국지성호우가 증가하고 있다. 엄청난 양의 폭우가 좁은 지역에 집중적으로 비를 뿌리면서 산사태와 축대 붕괴, 저지대 침수의 가능성 또한 커지고 있다. 도시지역은 도시개발로 인해 자연공간이 감소하여 개발 전 지표면이 가지고 있던 유역 내 저류 및 지연효과가 현저하게 감소하고 시가지의 확대와 도로포장 등 유역 내 불투수층의 증가로 인하여 홍수유출량과 첨두유출량이 점차 증가되고 있으며 유출구 까지의 도달시간은 자연유역에 비해 현격하게 짧아져 과거 자연하천 유역과는 다른 수문학적 특성을 가진다. <br> 특히, 도시집중 현상으로 택지 및 시설부지의 부족현상이 가중됨으로써 하천범람 구역이나 홍수우려가 있는 범람원내 저지대까지 도시화가 이루어짐으로써 치수상의 안전도가 상대적으로 저하되고 있는 한편, 도시유역에서 집중호우로 인한 홍수 피해는 다른 지역에 비해 상대적으로 피해규모가 증대되고 있다. 하지만 이러한 피해규모를 예측하기란 상당히 많은 어려움이 있으며, 이러한 피해를 정량적으로 분석하기엔 경제적 손실 금액을 산출하는 것이 필요하다 생각된다. 본 연구는 국지성호우로 인한 도시지역 피해사례 및 각 피해에 대한 개선 및 대책방안을 도출하기위한 위험도 산출 시 경제적 손실을 분석하기 위한 방안을 제안함으로써, 좀 더 객관적이고 정량적인 위험도 분석이 이루어지도록 한다.

Spontaneous resolution of aortic dissection is extremely rare and only a few cases have reported. We report on the case of an elderly man who presented with DeBakey type III aortic dissection, which was resolved spontaneously over two years after antihypertensive treatment. We also discuss the possible mechanism and the role of conservative management.

자외선 차단제는 자외선의 흡수 기능을 갖는 유기 계열과 반사 기능을 갖는 무기계로 구분된다. 이들은 SPF 지수로 평가되는데 in-vivo 실험은 높은 비용과 시간이 오래 걸리는 단점이 있어 in-vitro 평가가 연구에 많이 이용된다. 하지만 in-vitro 평가로 사용되는 SPF 평가 장치는 재현성이 매우 낮아 값에 대한 신뢰가 매우 어렵다. 또한, UV-vis spectrometer를 이용한 분석은 재현성은 높지만 투과/흡수/반사의 구분된 결과를 구하기 어려운 단점이 있다. 본 연구에서 제시하는 elipsometer는 높은 재현성과 투과/흡수/반사의 구분된 결과, 다양한 각도에서의 평가의 장점이 있어 자외선 차단제 평가에 매우 유용하다. 이를 위해 상업용 자외선 차단제를 다양한 방법으로 평가하여 elipsometer를 이용한 방법의 타당성을 알아보았다.

In recent years, environmental pollution by pharmaceuticals and personal care products (PPCPs) in the aquatic environment is of great concern worldwide. Recent studies have been reported to occur in a variety of environmental organisms such as surface, drinking and ground water, soils, sediments and hospitals. The purpose of this study was to evaluate the occurrence and environmental behavior of fourteen human PPCPs in surface waters of Mankyung River in South Korea. We were conducted to field survey for water quality and PPCPs analysis at November, 2006. PPCPs were analyzed by liquid chromatograph coupled with a tandem mass spectrometer (HPLC-MS/MS). The concentration of COD was measured to be 2.37～19.71 mg/L, which was belong to 4～5 grade in water quality criteria of lake. Station 2 that there is no pollution in upper stream, was appeared to lower concentration. The concentration of TN and TP, that is cause matter of eutrophication, were found to be 7.78～35.42 mg/L and 0.08～0.95 mg/L, respectively, which were exceeding 5 grade in Lake water quality criteria. The 11 kind of PPCPs compounds except levofloxacin and triclosan were detected to Mankyung river. PPCPs concentrations of STP(Sewer Treatment Plant) effluents and aquatic environment in Mankyung river have been detected in the range from dozens of ng/L to hundreds of μg/L that by order of atenolol, carbamazepine, propranolol, Ibuprofen, erythromycin, ifenprodil, clarithromycin, mefenamic acid, fluconazole, indomethacin, disopyramide. PPCPs concentration of Station 1 and 5, which was influenced by Jeonju STP and Wanju STP, was detected high values. Station 2 that there is no pollution, showed lower values. Station 3 which joined Gosan stream and Jeonju stream and station 4 which influenced by stock wastewater was detected to low values.

The modified biochemical oxygen demand (MBOD) were conducted to evaluate the water quality and fertility in the Mangyeong river from november 2002 to april 2003. MBOD method was used to evaluate algal growth potentials and their limiting factors. MBOD depends on the amount of available inorganic nutrient and organic substrate during 5-day incubation in the dark condition at 20℃. The MBOD assay depends on inorganic nutrients such as phosphorus and nitrogen as well as reduced carbon as called MBOD, MBOD-P, and MBOD-N, respectively. The concentration of pollutants were in the range of 3.08～48.36 mg/L for COD. The concentration of nutrients were in the range of 0.37～111.62 mg/L for dissolved inorganic nitrogen (DIN) and 0.00～1.03 mg/L for dissolved inorganic phosphorus (DIP). The results of MBOD bioassay showed that the MBOD, MBOD-P and MBOD-N values were 15～173 mg O2/L, 13～165 mg O2/L and 66～175 mg O2/L ranges, respectively. The MBOD values are found to be the highest in Iksan River and the lowest in Hari River throughout the Mangyeong River. The relationships of MBOD, MBOD-P and MBOD-N in MBOD method were generally found in MBOD≒MBOD-P≒MBOD-N. But the result of Gosan was appeared to MBOD≒MBOD-N>MBOD-P. The MBOD-N value was higher 3 to 5 times than the MBOD-P value in the Gosan station. The algal growth potentials expressed as the concentration of chlorophyll-a were maximum 20 times more than algal biomass in the water column.

To evaluate the change for water quality after the water gate operation in Shiwha lake, in situ survey were conducted on september in 2000 and January, march, jane in 2001. Chemical characteristics and eutrophication level was estimated from the survey data. The water quality of the Shihwa lake was greatly affected by pollutant load from rainfall, and formation of stratification in summer and winter was increased to effect on nutrient release from sediment. Especially, high concentration of chlorophyll-a was occurred in autumn, due to increased nutrient, high water temperature and low salinity after rainfall runoff. The mean concentration of DIN, DIP were 0.346mg/L, 0.0217mg/L in surface water and 0.826mg/L, 0.0415mg/L in bottom water, respectively, which were over Ⅲ grade of seawater standard. Also high percentage of ammonia nitrogen to DIN in bottom water for autumn and winter was affected by released nutrient from sediment. Correlation analysis of chlorophyll-a versus TSS was shown that organic matter was affected by autochthonous organic matter stem from the algae, these factor showed reverse correlation about salinity. Closely correlations among to the water quality constituent in continuity survey was appeared. The results of eutrophication index estimation showed the high potentiality of red tide occurrence in Shiwha lake, particularity in summer or fall. Overall water quality was greatly improve to compared with measuring data during 1997～1998 at the beginning water gate operation, which reported by KORDI. Therefore, to improve of water quality in Shiwha lake, we need to establish of management plan about nutrient release from sediment, rainfall runoff, maximum of seawater exchange.