• Tribology and Lubricants
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• v.31 no.2
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• pp.35-41
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• 2015

A water-pump located in the cooling area of a car circulates cooling water. A particular bearing element, known as a water-pump bearing, installed in the rotating part carries the entire load. The failure of this water-pump bearing has a direct impact on the failure of the automobile engine, and so securing its reliability is crucial. Several researchers have examined the design principles of the water-pump bearing, but there are no reports on the life characteristic of the bearing yet. Herein, we report the construction of test equipment to reproduce the spalling of the roller contact, which is the main failure mode of the chosen water-pump bearing. We chose the radial load as an accelerated stress factor and validated the failure mode by monitoring the surface defects. We conducted the accelerated life test after determining the accelerated stress level through a combination of finite element analysis and a preliminary test. In the life tests, we used an accelerometer to perform failure diagnosis. In the last stage of this study, we present a statistical reliability analysis. Thus, we fully estimated the shape parameter of the water-pump bearing, accelerating level on the load , and the lifetime (MTTF and B₁₀ life) under real use conditions, and finally proposed an interval estimation value considering the uncertainty of the estimated value.

• Journal of Advanced Marine Engineering and Technology
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• v.36 no.8
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• pp.1083-1090
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• 2012

Copper alloys are widely used for casting materials including ship's propellers and pump impellers as they provide high corrosion resistance. In addition, the demand for these alloys is increasing with rapid growth of offshore structures and exploitation of various substitute energy sources. However, they require regular maintenance because of erosion and cavitation damages induced by exposure to marine environment at high speed flows for a long period of time. Water cavitation peening have received attention as one of surface modifications for durability improvement of the copper alloys. This is a environment friendly technology without influence of heat and easily applicable to casting materials. In this research, water cavitation peening was employed in distilled water for copper alloy castings as a function of time and evaluation of corrosion resistance was followed in seawater for the modified surface by using electrochemical methods. The result suggests that the water cavitation peening for 2 minutes was found to be the optimal peening parameter in terms of durability and corrosion resistance.

• Proceedings of the Korean Society of Computer Information Conference
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• 2017.07a
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• pp.170-171
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• 2017

오늘날 바쁜 일상에 따라 화분관리의 어려움을 많이 느꼈다. 따라서 Raspberry, Arduino를 이용한 사용자 지향적인 화분관리시스템을 목표로 두고 개발 하여 체계화, 단순화, 간편화하였다. 본 논문은 현재 가장 많이 사용하는 습도 센서(Gravity: Analog Soil Moisture Sensor For Arduino)와 워터펌프(Peristaltic Liquid Pump with Silicone Tubing) 중심으로 개발하였다. 또한 편의성과 휴대성, 접근성에 수익성까지를 고려하여 앱을 구현, 이용함으로써 사용자에게 화분 관리에 대한 정보 관리를 용이하도록 하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.3
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• pp.164-169
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• 2006

A systematic methodology has been proposed to establish a reliable design of water pump system. A simplified steady-state dynamic model of water pump system has been developed to study the response of water pump system to the dynamic load mainly due to the run-out and unbalance. Design modifications are needed to strengthen the structural integrity of existing designs. Increasing the natural frequency of system is pursued to prevent a resonance from occurring in the engine excitation range. A computational reliability methodology combined with finite element analysis is used to identify the most significant factor affecting the system performance. This method considered influence of design control parameters for the performance of design. By including control factors to the system model in a systematic way, more reliable design is expected.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.5
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• pp.395-409
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• 2022

To overcome the limitation of conventional rock excavation methods, the excavation with abrasive waterjet has been actively developed. The abrasive waterjet excavation method has the effect of reducing blasting vibration and enhancing the excavation efficiency by forming a continuous free surface on the rock. However, the waterjet cutting performance varies with rock fracturing characteristics. Thus, it is necessary to analyze the cutting performance for various rocks in order to effectively utilize the waterjet excavation. In this study, cutting experiments with the high pressure waterjet system were performed for basalt and granite specimens. Water pressure, standoff distance, and traverse speed were determined as effective parameters for the abrasive waterjet cutting. The cutting depth and width of basalt specimens were analyzed to compare with granite results. The averaged cutting depth of basalt was shown in 41% deeper than granite; in addition, the averaged cutting width of basalt was formed by 18.5% narrower than granite. The results of this study are expected to be useful basic data for applying rock excavation site with low strength and high porosity such as basalt.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.2
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• pp.153-170
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• 2022

Waterjet has been comprehensively used in urban areas owing to a suitable technique for cutting concrete and rock, and low noise and vibration. Recently, the abrasive waterjet technique has been adopted and applied by the Korea Atomic Energy Research Institute to demolish concrete plugging without disturbing and damaging In-situ Demonstration of Engineered Barrier System in the disposal research tunnel. In this study, the use of abrasive waterjet in the tunnel was evaluated for practical applicability and the existing cutting model was compared with the experimental results. As a variable for waterjet cutting, multi-cutting, water flow rate, abrasive flow rate, and standoff distance were selected for the diversity of analysis. As regarding the practical application, the waterjet facilitated path selection for cutting the concrete plugging and prevented additional disturbances in the periphery. The pump's noise at idling was 64.9 dB which is satisfied with the noise regulatory standard, but it exceeded the standard at ejection to air and target concrete because the experiment was performed in the tunnel space. The experimental result showed that the error between the predicted and measured cutting volume was 12~13% for the first cut and 16% for second cut. The standoff distance had a significant influence on the cutting depth and width, and the error tended to decrease with decrement of standoff distance.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.109.2-109.2
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• 2016

현민지브이티(Genesis)는 중소기업청 중소기업개발지원사업의 일환으로 진행된 2014년도 구매조건부 신제품 개발사업에 선정되어 '극저온 G-M냉동기를 이용한 대용량 Cold Trap개발'과제를 수행하면서 32인치 급으로 수분에 대해서 30,000[L/s] 이상의 배기속도를 가지는 대형 CWP를 개발하고 있다. 1차년도(2015년) 목표는 80K에서 200W급 단단 G-M극저온 냉동기를 개발하는 것이고, 2차년도(2016년) 목표는 이를 장착하여 30,000[L/s]의 물 배기속도 능력을 갖춘 32인치(800mm)급 직부형(appendage) CWP를 개발하는 것이다. 여기에서 가장 큰 문제점은 CWP 시스템의 물 배기속도를 실제로 측정하는 것이다. 왜냐하면 지금까지는 물(H2O)이 가진 독특한 물리적 특성으로 인해 배기속도 측정에 많은 어려움이 있어 이론적으로 계산한 값을 사용해 왔다. (심지어 크라이오 펌프 제조사 조차도 실험하지 않고 이론적인 계산 값을 일반적으로 사용한다.) 그러나 최근 본 과제 외에 물 배기속도 측정에 관한 요구사례와 일부 크라이오 펌프 제조사에서 수행하고 있다는 보고가 있는 바, 실제 물배기속도 시스템을 구축하여 이론과 실제 사이의 차이와 측정의 어려움 등에 관해 규명하고자 하였다. 물 배기속도 측정 방법은 크게 2가지로 나눌 수 있다. 첫째, 시스템으로 흘리는 물의 양을 Liquid MFC를 이용하여 먼저 측정한 후 Vaporizer로 보내어 기화 시키며 배기속도를 측정하는 방법. 둘째, 물을 Vaporizer로 먼저 기화시킨 후에 High Temp. MFM으로 기체 유량을 측정하며 배기속도를 측정하는 방법이 그것이다. 이에 국내 최초로 두 가지 방법 모두를 사용하여 표준화 된 물 배기속도 측정 설비를 구축하였고, 20인치(500mm) 크라이오 펌프와 인라인(inline)형 CWP 모델에 대한 물 배기속도 측정을 성공적으로 완료할 수 있었다. 향후 본 시험 방법과 결과를 토대로 32인치(800mm) 직부형 CWP 모델에 대한 물 배기속도 측정시험을 수행하고자 한다.

• Journal of Institute of Convergence Technology
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• v.4 no.2
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• pp.61-65
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• 2014

Pressure distribution around rotating impeller blades in centrifugal pump has been main issue for design of efficient and high performance automotive water pump. In addition, pressure losses of inlet water pipes should be considered to reduce additional pressure drop and design high performance engine cooling system. In this paper, pressure distribution inside water pump and pressure drop between inlet and outlet of water pump are investigated numerically to design plastic water pump for clean diesel engine application. And the inlet geometry of water pump was considered to analysis the effect of inlet water pipe geometry on pressure distribution around impeller blades and outlet pressure. The prediction results are compared with experimental data to validate and determine optimal operation condition without water pump cavitation. Major design parameters such as blade angle, volute geometry, system pressure, and coolant flow rate are considered to confirm applying possibility of plastic blades to the clean diesel engine.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.495-496
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• 2021

코로나 19로 인하여 다중이용시설에 출입 시 정부 지침에 따라 QR코드 스캔, 출입 명부 작성, 체온 측정 등 방역절차를 지켜야한다. 본 연구에서는 방역 절차를 간편화하고 동합한 방역 시스템을 제안한다. QR코드 스캐너를 통하여 출입자의 신상 정보를 확인하며 체온 측정 모듈을 통하여 출입자의 체온을 측정한다. 추가적으로 워터펌프를 통하여 소독제를 분사하며 서보모터를 통하여 출입문을 열고 닫는다. 또한, 산업 현장에서는 알코올 측정 센서를 통하여 작업자의 알코올 수치를 측정하여 음주로 인한 산업사고도 예방한다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.05a
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• pp.741-742
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• 2016

IoT(Internet of Things) 기술이 급속도로 발전함에 따라 다양한 분야에 적용되고 있으며, 새로운 부가가치를 창출하고 있다. 최근에는 IoT 기술을 접목하여 도시 내부에 자동화된 농작물 재배시설을 설비하여 재배된 농작물을 직접 현지에 바로 공급할 수 있는 운영시스템을 구축하고 있다. 본 연구는 도심지 내부의 건물 옥상이나 농작물을 재배할 수 있는 임의의 공간에 온실을 설치하여 작물을 재배할 수 있는 환경을 원격으로 관리하는데 있다. 온실 내부의 환경 데이터를 계측하기 위한 온도, 습도, 조도, 토양상태, CO2 센스를 설치하여 온실 내부의 환경을 라즈베리파이2(raspberry Pi2)를 활용하여 계측하였다. 원격으로의 데이터 전송은 Wi-Fi를 이용하여 데이터를 전송하였으며, 중앙에서 관리된 관리정보를 통하여 온실 하우스의 내부 환경을 제어할 수 도록 모터(motor), 환풍기 팬, 조명용 Led, 워터 펌프 등을 제어하도록 하였다. 본 논문의 연구결과를 통하여 비닐하우스의 내부 상태를 계측하고, 다양한 구동장치를 제어할 수 있도록 IoT 기술을 편리하게 적용할 수 있는 라즈베리파이와 원격관리용 스마트 앱(app.)을 이용하여 비닐하우스 내부 관경을 편리하게 관리할 수 있음을 확인하였다.