공공하수 처리시설 방류수 T-N 기준을 만족하기 위해서는 호기조에서 질산화가 안정적으로 이루어져야 한다. 수온 및 pH가 질산화에 민감한 영향을 주고 있음에도 불구하고 기존 하수처리장 설계 시 동절기 저수온만 고려하고 호기조 pH는 상시 7.0으로 가정하여 설계하고 있다. 이에 본 연구에서는 MLE 공법 하수처리장의 생물반응조 유입수 알칼리도를 계절별로 파악하여 시뮬레이션을 수행하고, 알칼리도 변화가 호기조 pH 및 NH3-N 농도에 주는 영향을 확인하였다. 연구대상 처리장의 계절별 일평균 생물반응조 유입수 알칼리도는 춘/추절기 190 mg CaCO3/L, 하절기 185 mg CaCO3/L 그리고 동절기 210 mg CaCO3/L로 하절기에 저농도 알칼리도가 유입되는 것을 실험을 통해 파악하였다. 시뮬레이션 결과, 동절기 MLSS 농도가 2,500 mg/L인 경우, 유입수 알칼리도 변화와 관계없이 호기조 NH3-N 농도는 10 mg/L 이상이며 알칼리제 투입을 통한 목표 호기조 NH3-N 농도 2.5 mg/L 달성이 어려운 것으로 확인되었다. MLSS 농도가 3,000 및 3,500 mg/L인 경우에는 유입수 알칼리도에 따라 호기조 NH3-N 농도는 각각 1.3-5.0 mg/L와 0.8-3.1 mg/L의 범위인 것을 파악하였다. 춘/추절기 및 하절기 생물반응조 유입수 알칼리도가 하한치가 유입되는 경우, MLSS 및 DO 농도와 관계 없이 pH와 알칼리도가 제한 인자로 작용하여 호기조 NH3-N 농도 2.5 mg/L 이하를 만족하지 못하였다. 반면 유입수 알칼리도가 충분한 조건에서는 DO 및 MLSS 농도만 제어해도 안정적인 질산화가 가능한 것으로 나타났다. 또한 춘/추절기 및 하절기에 호기조 DO 농도가 1.0 mg/L가 되어도 질산화가 발생되는 것이 확인되어 처리장 운영에 있어서 탄소 발생 저감 방안이 수행될 수 있다.

This study selected two labor-intensive processes in harsh environments among domestic food production processes. It analyzed their improvement effectiveness using 3-dimensional (3D) simulation. The selected processes were the “frozen storage source transfer and dismantling process” (Case 1) and the “heavily loaded box transfer process” (Case 2). The layout, process sequence, man-hours, and output of each process were measured during a visit to a real food manufacturing factory. Based on the data measured, the 3D simulation model was visually analyzed to evaluate the operational processes. The number of workers, work rate, and throughput were also used as comparison and verification indicators before and after the improvement. The throughput of Case 1 and Case 2 increased by 44.8% and 69.7%, respectively, compared to the previous one, while the utilization rate showed high values despite the decrease, confirming that the actual selected process alone is a high-fatigue and high-risk process for workers. As a result of this study, it was determined that 3D simulation can provide a visual comparison to assess whether the actual process improvement has been accurately designed and implemented. Additionally, it was confirmed that preliminary verification of the process improvement is achievable.

Ball stud parts are manufactured by a cold forging process, and fastening with other parts is secured through a head part cutting process. In order to improve process quality, stabilization of the forging quality of the head is given priority. To this end, in this study, a predictive model was developed for the purpose of improving forging quality. The prediction accuracy of the model based on 450 data sets acquired from the manufacturing site was low. As a result of gradually multiplying the data set based on FE simulation, it was expected that it would be possible to develop a predictive model with an accuracy of about 95%. It is essential to build automated labeling of forging load and dimensional data at manufacturing sites, and to apply a refinement algorithm for filtering data sets. Finally, in order to optimize the ball stud manufacturing process, it is necessary to develop a quality prediction model linked to the forging and cutting processes.

Purpose: This study verified the effects of simulation-based communication education on the problem-solving process, communication self-efficacy, and communication ability of nursing college students. Methods: As an experimental study of single-group pre- and post-design, data were collected from April 12 to June 18, 2021, using a self-report questionnaire from 55 Year 4 nursing college students in city D. The collected data were analyzed in terms of frequency, paired t-test, and Pearson's correlation coefficients using the SPSS/WIN 23.0 program. Results: Our findings indicated that there were significant differences between the problem-solving process (t=-20.54, p<.001), communication self-efficacy (t=-15.31, p<.001), and communication ability (t=-3.62, p=.001) in communication before and after simulation-based communication education. Following simulation-based communication education, the communication ability of nursing students was evaluated through the problem-solving process (r=.46, p<.01), self-efficacy in communication (r=.37, p<.01), and problem-solving process by a doctor. Furthermore, it was found that there was a significant positive correlation with communication self-efficacy (r=.16, p<.01). Conclusion: It can be expected that the simulation -based communication education will improve nursing students’ problem-solving process, communication self-efficacy, and communication ability and thus contribute to high-quality nursing in related clinical situations. In addition, for a more effective communication education, research that could develop various scenarios in the clinical field and verify the effectiveness is required.

최근 환경규제가 강화됨에 따라 액화천연가스(Liquefied Natural Gas)를 이용하여 전력을 생산해내는 신규발전설비인 부유식 LNG 발전설비(floating LNG power plant)가 개발되고 있다. 부유식 LNG 발전설비는 운용 시 증발가스가 발생하고 이를 제거하거나 회수할 수 있는 시스템의 설계가 필요하다. 그러나 해양플랜트는 해상요건에 따라 설계가 상이하고, 부유식 LNG 발전설비의 설계 전 시행착오를 줄이기 위해 지속적으로 수정이 가능한 BOG 회수시스템 공정모사 모델이 필요하다. 따라서 본 연구에서는 상용공정시뮬레이션 프로그램을 통해 부유식 LNG 발전설비에 적합한 모델을 모델링하고자 냉매사용 유무에 따라 서로 다른 BOG(Boil-Off Gas) 회수시스템을 모델링하여 BOG의 회수율과 액화점을 비교 및 분석하였으며, 그 결과 질소냉매를 사용한 BOG 회수시스템 모델을 부유식 LNG 발전설비용 BOG 회수시스템 모델로 제안하고자 한다.

Demand for cosmetics with functionality and eco-friendliness has increased dramatically due to recent aging, well-being trends, and increased interest in beauty. Cosmetics production in 2014 was 8,970.4 billion won, an increase of about 50% compared to 6,014.6 billion won in 2010. In the midst of this, similar companies in intense competition are pursuing differentiated strategies and innovation activities to solve quality, price and delivery problems. In particular, cosmetics packaging work is getting more difficult due to the increasing bill of materials (BOM) and difficult assembly methods. Therefore, in this study, the following problems were identified and suggestions for the improvement of the packaging Many research laboratories such as biotechnology, chemistry, and pharmaceuticals, which are undergoing various studies, are equipped with ready-made laboratory safety equipments such as bio-safety workbenches, aseptic bases, and exhaust workbenches. However, most researchers are disadvantaged in using existing safety equipment. This is because existing safety equipment can not take into account all of the unique characteristics of the research. For this reason, researchers are demanding the development of customized safety equipment that is well suited to their research needs. process of Company C, which is facing difficult situation to respond to the customer 's delivery due to the 52 - hour work week. First, we used the stopwatch to find the difficulty process in the packaging process and show ways to improve it. Second, to improve the efficiency of line balancing in the packaging process, we integrate processes, improve work methods, and perform simple automation. As a result, the prepare loss for replacement was reduced by 1 minute from 5 minutes, resulting in a 23% increase in productivity from 112 ea./hour to 137ea./ hour per person. At this time, the LOB of the packaging process was improved from 70% to 82% by operating one more production line through one person per line, total 9 people saving.

Purpose: This study examined the effects of simulation-based education for high-risk maternity on evaluating problem-solving process, self-leadership, critical thinking disposition, and selfefficacy of nursing students. Method: This study was a one-group pretest-postest test design with 81 junior nursing students as participants. Data were collected from September 4 to December 11, 2019, after students completed their simulation practice class. Students completed a survey on their problem-solving process, self-leadership, critical thinking disposition, and self-efficacy at the beginning and end of the class. Data were analyzed using descriptive statistics, paired t-test, and Pearson’s correlation coefficients using the SPSS WIN 21.0 program. Results: Students’ problem-solving process (t=-7.06, p<.001), self-leadership (t=-3.08, p=.003), critical thinking disposition (t=-2.12, p=.037), and self-efficacy (t=-6.01, p<.001) showed significant improvement after the simulation-based education for high-risk maternity. There was a positive relation between problem-solving process and self-leadership (r=.52, p<.001), critical thinking disposition (r=.39, p<.001), and self-efficacy (r=.53, p<.001). Conclusion: There is a need to supplement the limitations of clinical practice education by providing a simulation-based education environment similar to a hospital since the experience of clinical practice alone is not sufficient to improve students' knowledge and skills. Results of this study may be used as a basic data for efficiently performing simulation-based education on high-risk maternity.

Powder characteristics, such as density, size, shape, thermal properties, and surface area, are of significant importance in the powder bed fusion (PBF) process. The powder required is exclusive for an efficient PBF process. In this study, the particle size distribution suitable for the powder bed fusion process was derived by modeling the PBF product using simulation software (GeoDict). The modeling was carried out by layering sintered powder with a large particle size distribution, with 50 μm being the largest particle size. The results of the simulation showed that the porosity decreased when the mean particle size of the powder was reduced or the standard deviation increased. The particle size distribution of prepared titanium powder by the atomization process was also studied. This study is expected to offer direction for studies related to powder production for additive manufacturing.

Purpose: The aim of this study was to examine the effect of prebriefing in the nursing process using video simulations on nurses’ critical thinking, simulation immersion, simulation confidence, clinical performance, and simulation satisfaction. Method: This study was a comparative survey between lectures and adoption of the nursing process with video in pre-briefing. The participants were 128 nursing students who had completed the Korean advanced life support program. Data were analyzed using χ2-test, independent t-test, and paired t-test using the SPSS 22.0 program. Results: Pre-briefing with Chmil’s concept, including theory, nursing process, and outcome, increased the clinical performance (t=2.03, p =.044) and critical thinking (t=2.48, p =.015) in this study. But there was no difference in simulation immersion, simulation confidence, or clinical satisfaction. Conclusion: The results indicate that simulation using Chmil’s concept was an effective educational method to increase critical thinking and clinical performance.

Purpose: This study was tried to identify the effects of simulation practice education on the clinical competence, critical thinking disposition and self-confidence of nursing process in new graduated nurses. Methods: This study was one group pre-post test design, participants are 50 new graduated nurses with less than 3 month of working experience. The simulation practice education applied the first semester of the third grade, over 15 weeks with 1 credit per 2 hours per week by two instructors with four scenarios. Data were analyzed by descriptive statistics, paired t-test, Pearson’s correlation coefficients using the SPSS WIN 21.0 program. Result: There was a significant difference simulation practice education on the clinical competence and critical thinking disposition in the new graduated nurses. There was a correlation between clinical competence and critical thinking disposition. Conclusion: New nurses' capacity can be strengthened by applying simulation practice education that improve the clinical performance by enhance the critical thinking Disposition.

산성가스 제거 공정에서 막-흡수 하이브리드 시스템 적용을 위한 설계를 수행하였다. 상용 공정 모사 기인 Promax version 4.0을 이용하여 아민 흡수 공정과 하이브리드 공정의 산성가스 제거 성능을 비교하였다. 전사 모사 결과를 통해 하이브리드 공정은 아민 용매 순환량, 에너지 소모량, 장치 사이즈가 아민 흡수 공정에 비하여 작아지는 것을 확인 할 수 있었다. 따라서, 컴팩트한 장치 사이즈와 에너지 절감 공정인 하이브리드 공정은 LNG-FPSO 천연가스 전처리 공정에 적용하기에 적합한 방안임을 확인하였다.

This study investigated the effect of the grinding media of a ball mill under various conditions on the raw material of copper powder during the milling process with a simulation of the discrete element method. Using the simulation of the three-dimensional motion of the grinding media in the stirred ball mill, we researched the grinding mechanism to calculate the force, kinetic energy, and medium velocity of the grinding media. The grinding behavior of the copper powder was investigated by scanning electron microscopy. We found that the particle size increased with an increasing rotation speed and milling time, and the particle morphology of the copper powder became more of a plate type. Nevertheless, the particle morphology slightly depended on the different grinding media of the ball mill. Moreover, the simulation results showed that rotation speed and ball size increased with the force and energy.

This present contribution examines by means of a discrete event and agent-based simulation the potential of a joint use of resources in the installation phase of offshore wind energy. To this end, wind farm projects to be installed simultaneously are being examined, the impact of weather restrictions on the processes of loading, transport and installation are also taken into consideration, and both the wind farm specific resource allocation and the approach of a resource pool or resource sharing, respectively, are being implemented. This study is motivated by the large number of wind farms that will be installed in the future and by the potential savings that might be realized through resource sharing. While, so far, the main driver of the resource sharing approach has been the end consumer market, it has been applied in more and more areas, even in relatively conservative industries such as logistics. After the presentation of the backgrounds and of the underlying methodology, and the description of the prior art in this context, the network of the offshore wind energy installation phase will be described. This is the basis for the subsequent determination of the savings potential of a shared resource utilization, which is determined by the performance indicators such as the total installation time and degree of utilization of the resources. The results of the simulation show that weather restrictions have a significant effect on the installation times and the usage times of the resources as well as on their degree of utilization. In addition, the resource sharing approach, has been identified to have significant savings potential for the offshore wind energy installation.

본 연구에서는 기존에 제안되었던 공정 중심 모델링 방법을 개선하여 조선소의 다양한 생산 정보와 제약조건을 효과적으 로 표현할 수 있도록 개선된 공정 중심 시뮬레이션 모델링 방법을 제안하였다. 그리고 이를 이용하여 시뮬레이션 모델을 구축할 수 있도록 다이어그램 구성 요소와 모델링 방법을 상세히 기술하였다. 이 모델링 방법에서는 복수의 제품과 설비가 공정에 투입되었을 때 우선순위를 지정할 수 있으며, 계층 구조를 가진 시뮬레이션 모델을 표현할 수 있도록 레이어 개념이 적용되어 있다. 그리고 조선 소 생산 계획 정보를 바탕으로 절단 공정부터 대조립 블록 조립 공정까지를 본 논문에서 제안하는 방법으로 모델링하다. 이를 통하여 본 논문에서 제안하는 방법이 단일 설비가 여러 용도로 사용되는 경우에 기존의 모델링 방법에 비하여 유리한 것을 확인하였다. 결과 적으로, 개선된 공정 중심 시뮬레이션 모델링 방법은 기존의 공정 중심 시뮬레이션 모델링 방법에서 표현하기 힘들었던 제약 조건과 흐름을 효과적으로 표현할 수 있으며, 계층 구조를 가진 조선소 생산 계획 검증 시뮬레이션 모델을 체계적으로 구축하는데 활용할 수 있다.

Particle morphology change and different experimental condition analysis during composite fabrication process by traditional ball milling with discrete element method (DEM) simulation were investigated. A simulation of the three dimensional motion of balls in a traditional ball mill for research on the grinding mechanism was carried out by DEM simulation. We studied the motion of the balls, the ball behavior energy and velocity; the forces acting on the balls were calculated using traditional ball milling as simulated by DEM. The effect of the operational variables such as the rotational speed, ball material and size on the flow velocity, collision force and total impact energy were analyzed. The results showed that increased rotation speed with interaction impact energy between balls and balls, balls and pots and walls and balls. The rotation speed increases with an increase of the impact energy. Experiments were conducted to quantify the grinding performance under the same conditions. Furthermore, the results showed that ball motion affects the particle morphology, which changed from irregular type to plate type with increasing rotation speed. The evolution was also found to depend on the impact energy increase of the grinding media. These findings are useful to understand and optimize the particle motion and grinding behavior of traditional ball mills.

매립지에서 발생되는 바이오 가스를 정제하여 고순도 메탄을 얻음으로써 높은 열량을 갖는 가스로 전환 시킬 수 있다. 이를 자동차 연료나 도시가스로 활용할 경우 경제적 효과가 매우 클 것으로 예상된다. 본 연구에서는 다양한 조건 의 공급기체 변화와 그에 따른 공정조건의 변화를 통해 최종 메탄농도 95%와 회수율 95%를 만족하는 3단 중공사막 모듈 재순환 공정에 대하여 메탄과 이산 화탄소 혼합기체 투과실험으로 얻은 메탄 분압의 함수로 나타낸 투과도를 이용하여 메탄농도 75%∼80%, 공급유량 30 L/min∼100 L/min, 공급압력 5 atm∼15 atm, 막면적 0.85 m2∼3.42 m2 으로 변화시켜 전산모사를 수행하였으며, 이러한 조건 변화들에 따른 메탄순도와 회수율의 변화를 전산모사 하고자 하였다.