• 한국ITS학회 논문지
• /
• 제20권4호
• /
• pp.71-82
• /
• 2021

본 연구에서는 세종시 포장도로 구간을 대상으로 모바일매핑시스템(MMS)과 딥러닝 균열 감지시스템을 활용한 도로포장 모니터링 방안을 제시하고 경제성 분석을 통한 최적 유지보수 공법을 제시하였다. 나아가, 기존 대부분의 연구에서는 도로포장 조사 차량에 의해 취득된 데이터를 활용한 사례가 대부분이었으나 본 연구에서는 직접 모니터링 조사를 통해 취득한 도로 포장 상태등급을 기준으로 경제성 분석을 실시하였다. 도로포장 상태 모니터링 결과 일반국도, 시도, 지방도의 순서대로 도로포장 상태가 양호한 것을 확인하였다. 또한 포장파손모델을 활용한 경제성 분석 결과, 예방적 유지보수공법인 마이크로서페이싱 공법을 적용하는 것이 유지보수비용과 이용자 편익 측면에서 가장 경제적인 것으로 나타났다. 본 연구의 성과는 지자체의 기반시설 관리계획 수립을 위한 기초적 자료로 활용될 것으로 기대된다.

• Computers and Concrete
• /
• 제32권1호
• /
• pp.61-74
• /
• 2023

This article investigates the wave propagation analysis of the imperfect functionally graded (FG) sandwich plates based on a novel simple four-variable integral quasi-3D higher-order shear deformation theory (HSDT). The thickness stretching effect is considered in the transverse displacement component. The presented formulation ensures a parabolic variation of the transverse shear stresses with zero-stresses at the top and the bottom surfaces without requiring any shear correction factors. The studied sandwich plates can be used in several sectors as areas of aircraft, construction, naval/marine, aerospace and wind energy systems, the sandwich structure is composed from three layers (two FG face sheets and isotropic core). The material properties in the FG faces sheet are computed according to a modified power law function with considering the porosity which may appear during the manufacturing process in the form of micro-voids in the layer body. The Hamilton principle is utilized to determine the four governing differential equations for wave propagation in FG plates which is reduced in terms of computation time and cost compared to the other conventional quasi-3D models. An eigenvalue equation is formulated for the analytical solution using a generalized displacements' solution form for wave propagation. The effects of porosity, temperature, moisture concentration, core thickness, and the material exponent on the plates' dispersion relations are examined by considering the thickness stretching influence.

• 대한환경공학회지
• /
• 제35권7호
• /
• pp.509-517
• /
• 2013

본 연구의 목적은 도심지역 중소하천의 효율적인 수질정화를 위해 물리화학적, 생물학적 처리공정을 결합한 장치형 하천수질정화공법의 적용성을 평가하는데 있다. 본 연구의 하천정화시설은 TSS 및 TP 제거를 위한 가압부상(Micro Bubble Process, MBP)공정과, BOD 제거를 위한 관로형 미생물 부착(Attached Microbial Pipe System, AMPS)공정으로 구성하였다. 각 장치의 실험 조건은 MBP 공정의 부상조 체류시간 및 초미세기포 주입량 변화와 AMPS 공정의 체류시간의 변화를 설정하였다. 또한 계절 변화에 따른 각 공정의 오염원 제거효율을 평가하였다. 각 공정의 연속운전 결과 MBP 공정에서는 최대 TSS 83.69%, TP 95.15%의 처리효율을 나타냈으며, AMPS 공정의 TBOD5 제거효율은 최대 53.0%를 나타냈다. 또한 각 공정의 순환운전 결과 MBP 공정에 의해 최대 TSS 69.75%, TP 70.17%의 처리효율을 나타냈으며, AMPS 공정에 의해 TBOD5 제거효율은 최대 68.58%를 나타냈다. 따라서 본 하천정화시설은 도심지역 내 오염된 하천의 수질을 개선하는데 효과적이라고 사료된다.

• 대한환경공학회지
• /
• 제38권9호
• /
• pp.513-520
• /
• 2016

수중에 용존된 가스뿐 아니라 소독부산물과 같은 휘발성 화합물은 탈기에 의해 효과적으로 제거할 수 있는 것으로 알려져 있다. 탈기공정에 사용되는 미세 기포는 수백~수천 ${\mu}m$이지만 부상 공정의 기포는 수 ${\mu}m$ 정도로 작다. 이에 따라 부상공정에서의 마이크로 기포는 수중의 휘발성 화합물이 대기로 방출될 수 있는 매우 넓은 기-액 비표면적을 제공한다. 또는 마이크로 기포는 상승 속도가 느려서 휘발성 화합물이 방출될 수 있는 긴 체류시간을 갖게 된다. 본 연구에서 일련의 탈기와 부상 실험을 실시한 결과, THMs의 제거율에서 상당히 큰 차이가 있었다. THMs의 물질전달계수 $K_La$ 역시 큰 차이를 보였다. 따라서 부상공정에서 THMs과 같은 휘발성 화합물을 제거하기 위해서는 일반적으로 입자제거를 위하여 적용되는 통상적인 운전범위보다 더 높은 기포체적농도가 필요함을 알 수 있다.

• 한국재료학회지
• /
• 제18권12호
• /
• pp.635-639
• /
• 2008

In this paper, experimental studies of the regrinding of tungsten carbide (WC-Co) tools for high-speed machining were conducted. Regrinding and a subsequent evaluation test were carried out for a flat endmill tool with diameters of 10 mm and 3 mm using a CNC five-axis tool grinder and a CNC three-axis machining center. Tool wear on the two types of endmill tools increased as the cutting length increased, and the tool wear was not influenced by the regrinding state. In case of the micro endmill with a tool diameter of 3 mm, the effective regrinding time was determined for a flank wear threshold of 0.3 mm considering the tool life according to cutting length. The tool lives of the 10 mm and 3 mm endmill tools were increased by 80% and 72%, respectively. This conclusion proves the Feasibility of the recycling of tungsten carbide materials in the high-speed machining of high-hardened materials for industrial applications.

• 농업과학연구
• /
• 제39권1호
• /
• pp.125-132
• /
• 2012

The 2009 Agricultural Survey is one of the most important official statistics about agricultural sector, which is mostly used by experts. However users have kept claiming about the problems of the 2009 Agricultural Survey, which need to be discussed in the academic area. The purpose of this paper is to analyze the 2009 Agricultural Survey and the level of satisfaction of users and to evaluate the 2009 Agricultural Survey. Then, the paper presents some suggestions to upgrade the 2009 Agricultural Survey. The results of studies present a few findings: First, the 2009 Agricultural Survey shows overall excellence but should focus on adding more various topics in agricultural sector, Second, the 2009 Agricultural Survey need to consider offering micro level data for experts such as data in the city or county level, Third, the 2009 Agricultural Survey had better to offer more specific examination and guide line for general users.

• KDI Journal of Economic Policy
• /
• 제40권1호
• /
• pp.67-83
• /
• 2018

We have hypothesized that nuclear risk is significantly inversely related to the distance from residences to nuclear power plants and that the level of life satisfaction of residents therefore increases with the distance. We empirically explore the relationship between Ulsan citizens' life satisfaction levels and the distance between their residences and the Kori and Wolsong nuclear power plants (NPP) based on the life satisfaction approach (LSA). The dataset we used covers only Ulsan citizens from the biennial Ulsan Statistics on Citizen's Living Condition and Consciousness of 2014 and 2016. Controlling for micro-variables such as education, work satisfaction, gender, marital status, and expenditures, we found a statistically significant relationship between life satisfaction and the distance between the residences and the nuclear power plants. Nuclear negative externalities including (i) health and environmental impact, (ii) radioactive waste disposal, and (iii) the effect of severe accidents can be quantified in terms of LS units and monetary units. We were able to calculate the monetary value of NPP externalities at $277 per kilometer of distance for Kori and $280 per kilometer of distance for Wolsong at constant 2015 prices. These estimates are quite different from the traditional estimates made with the contingent valuation method, whereas they are similar to the findings of LSA studies abroad. Hence, the need to adopt the LSA in South Korea and policy implications are demonstrated.

• 재활간호학회지
• /
• 제19권1호
• /
• pp.55-63
• /
• 2016

Purpose: The purpose of this study was to examine the characteristics of suicide attempters visiting emergency department in a general hospital located at local city. Methods: To investigate the characteristics of suicide attempters, the medical records of 201 suicide attempters were reviewed with a structured analytic sheet. Data were analyzed using ${\chi}^2$ test, two sample t-test, and oneway ANOVA. Results: Among total of 201 suicide attempters, 114 (56.7%) lived in rural areas. 114 (56.7%) were men and most of them (71, 35.3%) lived in rural areas. 155 (77.5%) was the first trier and the most frequently used method was taking pesticides. There were gender and regional differences in the suicide-related characteristics of suicide attempters. Conclusion: The results provide empirical evidences to design and implement strategies at both macro and micro levels to prevent suicide.

• 한국환경과학회지
• /
• 제20권6호
• /
• pp.767-773
• /
• 2011

The objectives of this research are to investigate the proper coagulation conditions which are a type and doses of coagulants, mixing conditions (velocity gradients and mixing times), pH and so on through Jar-test, to evaluate the flux variations, permeate, backwashing according to characteristics of pretreatment of the wastewater by means of MF membranes for river maintenance water reuse. The effluent water from B-city K-sewage treatment plant are used for this research. Turbidity and suspended solids(SS) are 14.2 NTU and 10.4 mg/L respectively. This condition causes fouling for membrane process. The flux decline could be reduced when coagulation pretreatment was carried out. Optimal coagulations PAC which are commonly used in the sewage treatment plant was observed in this research. The results indicate that an optimal coagulation dose and pH are 80 ppm and pH of 7 respectively, but coagulation efficiency was lower at strong acid or strong base. Results showed that continuous and steady operations in membrane separation process by means of the effective removal of organic matter and turbidity with coagulation pretreatment of sewage secondary effluent were achieved.

• 성인간호학회지
• /
• 제17권4호
• /
• pp.548-560
• /
• 2005

Purpose: High risk women with congenital heart disease decide to get pregnancy is determined by not individual autonomous intention but complex interaction with their physical status and socio-psychological environments. This study tried to the answer to the question. : "What is experience high risk women who have congenital heart disease during transition to parenthood?". Method: A micro-ethnographic research method and oral historic research approach were done at the Grown-Up Congenital Heart Disease Clinic in one Korean metropolitan city from July 2002 to September 2003. Result: It was discovered that high risk women's experience of transitional parenthood is accounted as the process of lonely and fearful self-accomplishment. Their need for self-accomplishment creates them seek more opportunities to increase enduring abilities for their parenthood. Conclusion: We suggest that from the time of beginning of patient's making decisions about becoming pregnant, collaborative efforts must be considered that priority level of patient's needs be reviewed and find appropriate advices for their situation. Special counseling program should be provided to all the prospective parents with understanding their meaning of parenthood.