본 연구에서는 소형선박용 중·고속 디젤엔진에 적용하여 연구 중인 SCR+DPF 기술을 저속엔진이 설치된 선박에 탑재하여 해상 실증 시험을 수행하였다. 대상 선박(총 톤수 2,881 톤, 정격출력 1,470kW@240rpm ×1)은 국내 연해를 운항하는 일반화물선으로 배출저감설 비의 선박 탑재를 위해 도면 개발, 승인 및 선박 임시검사를 수행하였다. 저감성능 확인을 위해서 가스상물질 측정장비는 NOx technical code 및 ISO-8178의 분석방법을 준용하는 장비를 사용하였으며, 입자상물질 측정장비는 국제해사기구(IMO)에서 논의하고 있는 블랙카본 측정 방법 중 하나인 스모크미터를 사용하였다. 시험은 황 함유량 따라 MGO(0.043%), LSFO(0.42%) 2종의 연료를 사용하였으며 실제 운항 하는 엔진회전수(130, 160 및 180 rpm)를 고려하여 시험 조건을 설정하였다. 시험 조건에 따라 배출저감설비의 전·후단에서 가스상 및 입 자상(매연) 물질을 측정하여 배출저감설비의 저감효율을 확인하였으며 모든 시험 조건에서 NOx의 경우 90% 이상, 입자상물질(매연)의 경우 95% 이상의 저감효율을 확인하였고 엔진 성능의 영향을 줄 수 있는 배기가스 압력은 허용배압 기준인 50mbar 이하를 만족하였다. 본 연구를 통해 해상실증 연구의 중요성과 중소형 저속엔진 선박의 질소산화물 및 입자상물질의 동시 저감을 위한 대응 기술로 SCR+DPF 설비 적용 가능성을 확인할 수 있었다.

Although the Ti–6Al–4V alloy has been used in the aircraft industry owing to its excellent mechanical properties and low density, the low formability of the alloy hinders broadening its applications. Recently, laser-powder bed fusion (L-PBF) has become a novel process for overcoming the limitations of the alloy (i.e., low formability), owing to the high degree of design freedom for the geometry of products having outstanding performance used in hightech applications. In this study, to investigate the effect of bulk shape on the microstructure and mechanical properties of L-PBFed Ti-6Al-4V alloys, two types of samples are fabricated using L-PBF: thick and thin samples. The thick sample exhibits lower strength and higher ductility than the thin sample owing to the larger grain size and lower residual dislocation density of the thick sample because of the heat input during the L-PBF process.

Because magnets fabricated using Nd-Fe-B exhibit excellent magnetic properties, this novel material is used in various high-tech industries. However, because of the brittleness and low formability of Nd-Fe-B magnets, the design freedom of shapes for improving the performance is limited based on conventional tooling and postprocessing. Laserpowder bed fusion (L-PBF), the most famous additive manufacturing (AM) technique, has recently emerged as a novel process for producing geometrically complex shapes of Nd-Fe-B parts owing to its high precision and good spatial resolution. However, because of the repeated thermal shock applied to the materials during L-PBF, it is difficult to fabricate a dense Nd-Fe-B magnet. In this study, a high-density (>96%) Nd-Fe-B magnet is successfully fabricated by minimizing the thermal residual stress caused by substrate heating during L-PBF.

Anomaly detection for each industrial machine is recognized as one of the essential techniques for machine condition monitoring and preventive maintenance. Anomaly detection of industrial machinery relies on various diagonal data from equipped sensors, such as temperature, pressure, electric current, vibration, and sound, to name a few. Among these data, sound data are easy to collect in the factory due to the relatively low installation cost of microphones to existing facilities. We develop a real time anomalous sound detection (ASD) system with the use of Autoencoder (AE) models in the industrial environments. The proposed processing pipeline makes use of the audio features extracted from the streaming audio signal captured by a single-channel microphone. The pipeline trains AE model by the collected normal sound. In real factory applications, the reconstruction error generated by the trained AE model with new input sound streaming is calculated to measure the degree of abnormality of the sound event. The sound is identified as anomalous if the reconstruction error exceeds the preset threshold. In our experiment on the CNC milling machining, the proposed system shows 0.9877 area under curve (AUC) score.

본 논문은 14~20대 국회 고용보험 관련 법률안 318건을 대상으로 의 원·정부의 입법관심 정책영역과 정책영역별 입법결과를 분석했다. 한 법 률 전체를 동일 정책영역으로 간주하는 기존 연구와는 달리 본 논문은 정책과정모형, 사회보험분석틀을 수정 및 보완하여 의안원문의 개별 개 정안을 정책영역별로 분류했다. 분석결과, <정책의제>에서 의원·정부의 입법관심이 가장 높은 정책영역은 실업급여사업이었고 정부의 이념적 성 향이 정책 입안에도 드러났다. 고용안정·직업능력개발사업은 경제상황에 따라 의원·정부의 입법관심이 증감했고, 모성보호사업은 정부보다 의원이 더 높은 입법관심을 보였다. 입법결과의 경우 정부는 고용안정·직업능력 개발사업의 정책 수에서 의원을 앞섰는데, 실업급여사업과 모성보호사업 은 정부안 가결률이 높고 입법성공 정책 수는 의원안에서 더 많았다. <행정체계>의 전체 정책영역에서 정부 정책안의 입법 성공률이 의원안보 다 더 높고 특히 재정정책은 정부가 주된 입법주체임을 확인했다. 결론 적으로 정책영역에 따라 법률적 변화를 견인하는 입법주체가 다르다는 점과 의원·정부의 입법관심 영역과 입법성공 가능성을 고려해 입법논의 가 이뤄진다면 효율적일 것이다.

Recently, due to the rapid increase in vehicle accidents, research on improving seat belts and restraint system are being actively on going to solve the problems in vehicle for passengers. The characteristics of lap belt load and pelvic displacement were simulated through MADYMO program using Hybrid III 50th percentile male dummy to analyze the submarining by changing the collision speed and seat back angle by applying the forward collision pulse form accident scenario. As a result, the submarining occurred when the seat-back angle was 60° or higher at the collision speed of 50km/h or higher. Lastly, using the characteristics of the lap belt load and pelvic displacement when the anti-submarining belt (ANSB) system adapted, the pelvic displacement was reduced as well as submarining.

This study focused on natural organic matter and trihalomethane removal by ozonation with various ferrous concentration in surface water. Ozonation is more affected by injection concentration than reaction time. dissolved organic carbon removal rates in ozonation increased with the increase in ferrous concentration. The highest removal was obtained at 6 mg/L of ferrous concentration. When 1 mg/L of ferrous was added with 2 mg/L of ozone concentration, it was found to be a rapid decrease in specific ultraviolet absorbance at the beginning of the reaction because ferrous acts as a catalyst for producing hydroxyl radical in ozonation. As ozone concentration increased, trihalomethane formation potential decreased. When 2 mg/L of ozone was injected, trihalomethane formation potential was shown to decrease and then increase again with the increase in ferrous concentration.

PURPOSES: The objective of this study is to evaluate the structural capacity of asphalt pavement in subsurface cavity sections using falling weight deflectometer (FWD) backcalculation method. METHODS: It is necessary to analyze the reduction of structural capacity in asphalt pavements due to the occurrence of subsurface cavities. The FWD testing was conducted on the cavity and intact asphalt pavement in the city of Seoul. The GAPAVE, backcalculation program for FWD deflections, was utilized to determine the layer moduli in asphalt pavements. The remaining life of asphalt pavements in cavity sections were predicted using the pavement performance model for fatigue cracking. The backcalculated layer moduli between cavity and intact sections were compared to determine the reduction of structural capacity due to subsurface cavity. The relationship between the reduction of layer modulus and cavity depth/length was analyzed to estimate the effect of cavity characteristics on the structural capacity degradation. RESULTS: According to the FWD backcalculation results, the modulus of asphalt layer, subbase, and subgrade in cavity sections are generally lower than those in intact sections. In the case of asphalt layers, the backcalculated modulus in cavity section was reduced by 50% compared to intact section. A study for the prediction of remaining life of cavity section shows that the occurrence of subsurface cavity induces the decrease of the pavement life significantly. It is found that there is no close relationship between the backcalculated modulus and cavity length. However, the reduction of asphalt layer modulus is highly correlated with the cavity depth and was found to increase with the decrease of cavity depth. CONCLUSIONS : This reduction of structural capacity due to the occurrence of cavities underneath asphalt pavements was determined using FWD backcalculation analysis. In the future, this approach will be utilized to establish the criteria of road collapse risk and predict the remaining life of cavity sections under numerous varied conditions.

This study is focused on effects of factors that affect the formation of THMs during chlorination in drinking water treatment. During the chlorination, chlorine consumption is increased by increasing the initial chlorine dose, the pH and the total dissolved solid (TDS) concentration. Also THMs formation is increased up to 58.82 μg/L and 55.54 μg/L by increasing initial chlorine concentration and increasing pH. However, concentration of chloroform is decreased by increasing TDS concentration. This is caused the cation(Na+) of the total dissolved solids preferentially reacts with the functional groups of the organic material which influence the trihalomethane formation. But total trihalomethane formation is increased up to 127.46 μg/L by Br- contained in the total dissolved solids. DOC reduction was not influenced by any of the factors.

PURPOSES: The objective of this study was to develop an asphalt pavement response model for a subsurface cavity section using the 3D finite element method and a statistical approach. METHODS: It is necessary to analyze the structural behavior of asphalt pavement with a subsurface cavity to evaluate the degree of risk for a road cave-in. A 3D finite element model was developed to simulate the subsurface cavity underneath asphalt pavement and was verified using the ILLIPAVE program. Finite element analysis was conducted for asphalt pavement sections with different asphalt layer thickness/modulus, and cavity depth and length, to generate the artificial pavement response database. The critical pavement response considered in this study was the tensile strain at the bottom of the asphalt layer because fatigue cracking is the main cause of road cave-in. The relationship between the critical pavement response and influencing factors was investigated using the pavement response database. The statistical regression approach was adopted to develop the asphalt pavement response model for predicting the critical pavement response of asphalt pavement with a subsurface cavity. RESULTS : It was found from the sensitivity analysis that the asphalt layer thickness or modulus, and cavity depth or length, are the major factors affecting road cave-in incidents involving asphalt pavement. The asphalt pavement response model showed high accuracy in predicting the tensile strain at the bottom of asphalt layer. It was found from the verification study that the R square value between finite element model and pavement response model were 0.969 and 0.978 in the cavity and intact sections, respectively. CONCLUSIONS: The work reported in this paper was intended to figure out the pavement structural behavior and to develop a pavement response model for the occurrence of cavities underneath asphalt pavement using 3D finite element analysis. In the future, critical pavement response will be utilized to establish the criteria of risk of road cave-in based on various different conditions.

This study is focused on manganese (Mn(II)) removal by ozonation in surface water. Instant ozone demand for the water was 0.5 mg/L in the study. When 0.5 mg/L of Mn(II) is existed in water, the optimum ozone concentration was 1.25 mg/L with reaction time 10 minutes to meet the drinking water regulation. The ozone concentration to meet the drinking water regulation was much higher than the stoichiometric concentration. The reaction of soluble manganese removal was so fast that the reaction time does not affect the removal dramatically. When Mn(II) is existed with Fe, the removal of Mn(II) was not affected by Fe ion. However As(V) is existed as co-ion the removal of Mn(II) was decreased by 10%. Adding ozone to surface water has limited effect to remove dissolved organic matter. When ozone is used as oxidant to remove Mn(II) in the water, the existing co-ion should be evaluated to determine optimum concentration.

With the advent of the fourth industrial revolution, the digital transformation craze has intensified in diverse industries, such as finance, automotive, health care and agriculture. However, relative to industry demand, there is only few domestic research on digital transformation of small traders and no one has implemented empirical study on this field at all. Thus, the study conducted an empirical study to measure the digital transformation intention of domestic small traders. In the early days of domestic business start-ups, we searched for factors affecting the digital conversion intention of small business owners and designed an integrated framework to explain the causal relationship between factors. This study not only expanded and refined the scope of related research but also suggested the direction of another research that was not presented in previous research. However, there are limitations in many ways as much as the initial stage of a specific field of small business owners. There are limitations in explaining the overall perception of Korean small business owners. Therefore, in future studies, it is necessary to study more deeply by presenting more specific and various variables. In addition, although the number of respondents was sufficient in the process of empirical analysis, it is considered that the respondents are not enough to universalize the research result as a traditional small business person who did not convert all digital. It is necessary to carry out a comparative analysis by dividing the two groups in more detail and more specifically in the future study. The result of this study can suggest the direction for accelerating small traders’ digital transformation intention in terms of practical view, and provide useful references which can support the theoretical foundation for researchers who will perform future related research in terms of academic view.

PURPOSES : The objective of this study is to evaluate the potential risk level of road cave-ins due to subsurface cavities based on the deflection basin measured with falling weight deflectometer (FWD) tests. METHODS: Ground penetrating radar (GPR) tests were conducted to detect road cavities. Then FWD tests were conducted on 13 pavement test sections with and without a cavity. FWD deflections and a deflection ratio was used to evaluate the effect of geometry of the cavity and pavement for road cave-in potentials. RESULTS: FWD deflection of cavity sections measured at 60 cm or a closer offset distance to a loading center were 50% greater than more robust sections. The average deflection ratio of the cavity sections to robust sections were 1.78 for high risk level cavities, 1.51 for medium risk level cavities, and 1.16 for low risk level cavities. The relative remaining service life of pavement with a cavity evaluated with an surface curvature index (SCI) was 8.1% for the high level, 21.8% for the medium level, and 89.8% compared to pavement without a cavity. CONCLUSIONS : FWD tests can be applied to detect a subsurface cavity by comparing FWD deflections with and without a cavity measured at 60 cm or a closer offset distance to loading center. In addition, the relative remaining service life of cavity sections based on the SCI can used to evaluate road cave-in potentials.