• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2010년도 제35회 추계학술대회논문집
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• pp.359-362
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• 2010

155mm 탄약에 사용되는 항력감소제는 다년간의 생산을 통해 안정적인 성능 및 품질 신뢰도를 확보하여 왔다. 이러한 기반 하에 비행시험 평가 대체기법의 타당성에 대한 연구를 수행하였으며 이를 통해 품질 안정성에 대한 확인뿐 아니라 비용감소, 시험 적체 해소 및 전력화 지연 방지 등의 대내외적인 효과를 얻을 수 있을 것으로 기대된다.

• 한국자동차공학회논문집
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• 제25권2호
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• pp.207-218
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• 2017

Improving fuel consumption, particularly that of commercial vehicles, has become a global concern. The reduction in logistics cost has been a key issue in efforts to improve fuel economy and efficiency of transportation equipment. Typical technologies for reducing reduce fuel usage include air resistance reduction technologies, tire rolling resistance technologies, and idle technologies among others. Air resistance technology is a highly effective method that can be easily applied in a short period. As with air resistance technology, several devices involving side skirt, boat tail and gap fairing have been developed based on an analytical 3-D modeling technique for reducing air resistance attributed to the vehicle configuration. The devices were on a 45 feet tractor-trailer and the emission test was done using PEMS equipment. Fuel economy was evaluated by introducing several devices to reduce outer air resistance. The test was conducted by changing the experimental method of SAE J1321 Joint TMC/SAE Fuel Consumption Test Procedure - Type II test. As a result, air resistance decreased by at least 15 % and fuel economy improved by at least 13 %. This study sought to reduce greenhouse gas and improve fuel economy by applying several devices to a test vehicle to lower air resistance.

• Geomechanics and Engineering
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• 제32권5호
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• pp.503-512
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• 2023

In tunneling projects, a significant part of the costs is spent on segment production. By more economically producing, the cost of tunnel construction can be greatly reduced, especially in long and large-diameter tunnels. In the present study, the effect of using the Carousel method in the improvement of the production system performance compared to the conventional Static system has been studied. To carry out the research, a quantitative comparison of cost and production time was carried out for two production methods using the available documentation. The opinions of experts have been obtained using questionnaires and qualitative comparison of cost, time and production quality was done by implementation of statistical analysis. The SPSS software and the univariate t-test were used to analyze the questionnaires. According to the results of statistical analysis with SPSS, the use of the Carousel method will reduce production time and costs along with increasing manufacturing quality. According to the documentation analysis, the Carousel method reduces the cost of production by almost 30% and leads to a reduction of the production time to approximately 40% of the Static moulds system. The Carousel method has a higher production rate, efficiency, and better performance. Research into quantifying the benefits of Carousel method in the production system performance is very limited. This comparison is based on real information from the under construction Tabriz Metro project. This article can be very helpful in choosing the best production method.

• 한국수소및신에너지학회논문집
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• 제25권5호
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• pp.516-524
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• 2014

Proper discharge of nitrogen gas and water condensate is required in a conventional fuel cell system for performance, stability and durability of fuel cell stacks. Present study covers the development of integrated unit and its functioning logic for simultaneous nitrogen gas purge and water condensate drainage in a fuel cell vehicle system. Configuration of condensate drainage pipe, purge valve and level sensor is considered and optimized in physical integration. As a key factor, discharge time is considered and optimized based on the test result of constant-current operation with various operating temperature in logic development. Consequently, derived optimal values are applied and verified in actual vehicle drive mode test. Increase of system design flexibility, weight reduction and cost reduction are anticipated with this study. Additional study for physical and logical improvement is currently being implemented.

• 한국정밀공학회지
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• 제33권10호
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• pp.781-787
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• 2016

We introduce FEST (Flight Environment Simulation Test) procedures for precise guided missiles to reliably improve systems. Flight vibration specification was established based on power spectral density curves calculated from flight test data of a high speed precise guided missile. A FEST pre-profile was developed according to flight vibration specification and delivered to a precise guided missile assembly. Vibration responses were measured by installing accelerometers on electronic components vulnerable to dynamic forces. The FEST profile was adjusted by comparing the vibration responses and the flight vibration specification. Subsequently, the FEST profile was repeatedly modified through trial and error, because the responses were similar to the flight environment. The modified FEST profile enabled performance testing of assembled precise guided missiles under simulated flight conditions on the ground, where unexpected errors could be corrected before the flight tests, leading to cost and risk reduction in the development of the precise guided missile system.

• 한국컴퓨터정보학회논문지
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• 제5권2호
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• pp.7-13
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• 2000

객체지향 프로그램의 테스트 적합성 기준에 근거한 구현기반 클래스 테스팅 방법을 제안한다. 데이터 멤버간 종속성과 테스트 데이터 적합성에 대한 공리들을 고려하여 흐름 그래프 기반 테스팅 기준을 만족시키는 테스트 케이스인 메소드의 시퀀스를 생성시킨다. 파생 클래스 테스팅을 위해서 유산관계와 실험을 통해 테스트 비용 절감을 검증한 부모 클래스에 대한 테스팅 정보의 재사용성을 고려한다.

• 항공우주시스템공학회지
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• 제9권3호
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• pp.31-38
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• 2015

Wind Turbines are becoming larger in size in order to improve economic efficiency through cost reduction, such as the construction of growth and power infrastructure of energy efficiency. It have requested the large-scale blade design and production. In the present study the new manufacture technique called a fabric-blade structure using spar, rib, and fabric membrane skin is introduced. The architectural membrane test method has been studied to be applied to the skin of the blade. The density and one-axis tensile tests of the architectural membrane materials are conducted to confirm the physical properties which are necessary to the structural designs and analyses of the wind turbine blade.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제41권
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• pp.35.1-35.7
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• 2019

Background: The purpose of this study was to measure the time of the conventional surgical planning (CSP) and virtual surgical planning (VSP) in orthognathic surgery and to compare them in terms of cost. Material and method: This is a retrospective study of the patients who underwent orthognathic surgery at the Pusan National University Dental Hospital from December 2017 to August 2018. All the patients were analyzed through both CSP and VSP, and all the surgical stents were fabricated through manual and three-dimensional (3D) printing. The predictor variables were the planning method (CSP vs. VSP) and the surgery type (group I: Le Fort I osteotomy + bilateral sagittal split osteotomy [LFI+BSSO] or group II: only bilateral sagittal split osteotomy [BSSO]), and the outcomes were the time and cost. The results were analyzed using the paired t test. Results: Thirty patients (12 females, 18 males) met the inclusion criteria, and 17 patients were excluded from the study due to missing or incomplete data. There were 20 group I patients (LFI+BSSO regardless of genioplasty) and 10 group II patients (BSSO regardless of genioplasty). The average time of CSP for group I was 385 ± 7.8 min, and that for group II was 195 ± 8.33 min. The time reduction rate of VSP compared with CSP was 62.8% in group I and 41.5% in group II. On the other hand, there was no statistically significant cost reduction. Conclusions: The time investment in VSP in this study was significantly smaller than that in CSP, and the difference was greater in group I than in group II.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2011년도 추계학술대회 논문집
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• pp.658-663
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• 2011

The purpose of this study is to develop an air-passing soundproofing panel with more improved structure to reduce the $CO_2$ emission and installation cost. To reduce the emission of $CO_2$ ; it is suggested to choose low $CO_2$ emission material relative to the aluminum and to reduce the materials by developing a specially designed air-passing soundproofing panel structure. First of all, we performed the flow analysis to predict the wind pressure according to the open angle of the air-passing soundproofing panel and the noise level analysis at the receiver point. To verify the simulation, a prototype of the soundproofing panel was made. The flow test in the wind tunnel and load test were performed. The economic evaluation for the installation of the air-passing soundproofing panel was performed and specifications of the installation was prepared. As the results of this research, it was verified that the wind load was reduced about 40% to that of the conventional one at 25m/s wind speed in the wind tunnel test. By applying the 4m span soundproofing wall with air-passing soundproofing panel and under the cost of 250 thousand $won/m^2$ instead of the conventional 2m span panel, the installation cost will always be lowered than the conventional one in the combination of (60:40~50:50) conventional to air-passing soundproofing panel from the economic evaluation. The 20% reduction of $CO_2$ was found by changing the 50% of aluminum soundproof panel to air-passing soundproofing panel.

• 한국산학기술학회논문지
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• 제10권10호
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• pp.3011-3022
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• 2009

본 연구에서는 ASP 도입에 미치는 영향 요인을 조직 요인, 시스템 요인, 환경 요인 등을 독립 변수로 설정하고, 공급사와 고객사 간의 적합성을 조절 변수로 설정하였으며 종속 변수는 ASP 도입 성과로 설정하였다. 검증 결과 독립 변수들 가운데 유일하게 비용 절감의 기대 요인만이 ASP 도입 성과에 긍정적인 영향을 미치지 않는 것으로 분석되었다. 또한, 조절변수로 설정된 공급사와 고객사 간의 적합성 요인은 독립 변수 중 유일하게 비용 절감의 기대요인과 ASP 도입 성과 간에 조절적인 영향을 미치지 않는 것으로 분석되었다.