PURPOSES : This study aimed to secure the work space in alarm valve rooms to ensure stable working conditions for the engineers. METHODS : We analyzed situations where alarm valve room work spaces were inadequately secured posing a problem. Using the Ovako working posture analysis system (OWAS) method, we measured the body size of adult male technicians and their tools to analyze the actual space needed for them to maintain a healthy posture while working. On this basis, we proposed regulations governing workspace size and acceptable durations for unstable body postures. RESULTS : By measuring valve room work space and technician body size, we found that the workspace was inadequate for technicians. Applying OWAS showed that securing more space in the valve room improved the construction stability. CONCLUSIONS : Regulations on valve room size and appropriate work space for technicians will improve construction and inspection stability. This reduces the probability of poor construction and inadequate inspection, increasing the reliability of the firefighting facility system.

In this study, a numerical analysis study was conducted on the flow characteristics according to the internal flow path change and differential pressure of the hydrogen shut-off valve, and through this, the pressure loss characteristics and flow coefficient of the hydrogen shut-off valve were predicted. ANSYS CFX program was used to predict the flow characteristics of the hydrogen shut-off valve. When the flow path gap was 1.3 mm, the design conditions of the hydrogen shut-off valve were satisfied, and the value of the flow coefficient of the valve was about 1.53. As the inlet pressure of the hydrogen shut-off valve increases, the outlet flow rate increases, but regardless of the inlet pressure, the flow coefficient of the valve is almost constant, ranging from 1.53 to 1.56, indicating that it is the inherent flow coefficient of the designed hydrogen shut-off valve.

In the semiconductor manufacturing clean room, contamination that directly affects process yield is managed through the operation of a monitoring system that measures molecular contamination in the air. In this study, I presented the component inspection method, test conditions, and judgment criteria through the life test of the solenoid valve that will be applied to the sampling module of the AMC Monitoring System.

Recently, in the case of the root industry, although it is a basic industry that forms the basis of manufacturing competitiveness, there continues to be a shortage of manpower due to reasons such as dangerous working environments, industrial economic difficulties, and low wage systems. In addition, the demand for automation of production lines using robots is increasing due to a shrinking labor market due to a decrease in the working population due to aging, higher wages, shorter working hours, and limitations of foreign workers. In this study, a system was developed to automate the injection molding process for producing ball valves for automobiles by applying robot system. The applied process flow consists of alignment and insertion of insert parts, and removal, transfer, and loading of the product after injection molding, which is currently performed manually. Through the application of the developed robot automation system, the cycle time was improved by more than 30% and the defect rate was reduced by more than 70%.

The domestic shipbuilding industry is building high-value-added ships such as LNG and LPG, and the demand for natural gas, a clean energy source, is continuously increasing. Climate change, such as global warming, is occurring due to rising oil prices and excessive use of fossil fuels. To protect their homes from the changing environment, 121 countries announced intensive climate target policies to reduce carbon emissions to 0% by 2050. In this study, modeling and design were performed using SUS410 and SUS304L about the operating part of the Pilot valve based on the physical properties of the aluminum alloy used in the Pilot valve, a component of the gas pressure Regulating valve for LNG ships. Numerical We want to develop the optimal Pilot valve by comparing and analyzing the results using ANSYS, an analysis simulation program.

In this study, a vibrating nozzle using the waste vibration energy of the compressor body was installed in the suction flow path to improve the efficiency of the compressor through the pre-compression. To this end, the behavior of the suction valve according to the vibrating nozzle and the mass flow rate of the refrigerant entering the compression chamber were numerically analyzed. The results showed that the mass flow rate increased proportionally as the angle of the vibration nozzle increased. Among the profile shapes of the vibration nozzle, the concave or straight shape showed the highest mass flow rate. Considering the ease of machining, the straight shape is more favorable. On the other hand, as the operating frequency and stroke of the vibration nozzle increased, the mass flow rate also increased proportionally. It can be seen that the largest nozzle angle, operating frequency, and stroke are favorable for pre-compression unless the suction flow is restricted.. In the future, it is necessary to apply the vibrating nozzle system to an actual compressor model to experimentally check the compressor's cooling power, compression work and EER.

Gate valves are hydraulic components used to shut-off the water flow in water distribution systems. Gate valves may fail owing to various aspects such as leakage through seats, wearing of packing, and corrosion. Because it is considerably challenging to detect valve malfunctioning until the operator identifies a significant fault, failure of the gate valve may lead to a severe accident event associated with water distribution systems. In this study, we proposed a methodology to diagnose the faults of gate valves. To measure the pressure difference across a gate valve, two pressure transducers were installed before and after the gate valve in a pilot-scaled water distribution system. The obtained time-series pressure difference data were analyzed using a machine learning algorithm to diagnose faults. The validation of whether the flow rate of the pipeline can be predicted based on the pressure difference between the upstream and downstream sides of the valve was also performed.

The flange spreader has been used to withdraw butterfly valves during maintenance. The typical flange spreaders required an excessive working space, and the pipe and flange are damaged by the load. In the previous study, the author developed a valve easy out tool with collet, and designed collet shape to ensure structural safety. However, clamping force of the collet had not been checked. In this study, design of collet shape was performed to improve clamping force. Techniques of structural analysis were established and design parameters were selected. Through parametric study, the collet shape with clamping force of 159,748N was suggested. This will contribute to stability and efficiently of valve maintenance.

Most of the steam turbine control valves used for the fossil and nuclear power plants operation in South Korea were developed by GE (General Electric) and manufactured by DHIC (Doosan Heavy Industry Company). For may years, DHIC have tried to develop their own technologies related to the power generation. DHIC has launched many R&D projects and ‘Development of a Control Valve Flow Code for Steam Turbine Operation Control of Fossil Power Plant’ was one of the R&D projects. Through our project, we accomplished the experimental method to obtain a steam turbine control valve characteristic curve using the atmospheric air and the reduced model instead using the steam and the real model. Also, we developed the correction method to calculate the real steam mass flow rate from the characteristic curve obtain by the experiment. In this paper, the effectiveness of the correction method was reviewed and it was concluded that the corrected mass flow rate complies well with the real steam mass flow rate.

The flange spreader has been used to withdraw gaskets and valves during butterfly valve maintenance. When using the conventional flange spreader, an excessive working space (pipe separation distance) appears, and the pipe and flange are damaged by the load. Also, the equipment can’t be operated safely when the pipe has eccentric fitting. To solve the problems, a valve easy out tool with collet was developed for safely fixing and spreading flange. By using Ansys Workbench 2021 R2, the structural analysis of the original collet was performed, and shape design of the collet was carried out to improve structural safety.

In order to cope with climate change, the UN Climate Summit announced a policy to reduce carbon emissions to 0% by 2050. As a result, hydrogen energy is attracting attention as a new energy. Hydrogen energy is one of the future clean energy sources and is the most abundant and ideal fuel on Earth that does not emit pollutants. On the other hand, there is a risk of wide explosion range, easy ignition, and fast flame speed. As a result, There is limited use of hydrogen gases, and research is being conducted to safely use hydrogen gases. However, the localization rate of hydrogen-related equipment parts is low and dependence on foreign countries is high. In order to reduce dependence on foreign countries, this study designed and analysis a model of ultra-high pressure relief valve, which is a safety device for hydrogen charging stations. In order to evaluate the structural stability, a spring, a valve disk, a valve guide, and a valve spindle, which are components of an ultra high pressure relief valve, were applied with pressure resistance test and water pressure test criteria according to KS B ISO 19880-3, and analyzed using an Ansys workbench 2021 R1. Through the analysis results, the structural stability of the relief valve under the water pressure test and the pressure resistance test conditions confirmed.

Motor-operated valve functions to block or connect the flow of fluid in nuclear power plant and especially safety-related valves are evaluated with operability margin calculations, that should have positive value in both open and close stroke. Although all actuators have inertia force which increase operating margin of valve closing stroke, inertia force, after control switch operation in actuator is not considered in evaluating operability margin calculation process. In this paper, the hidden margin by inertia force of each actuator model in closing stroke was studied quantitatively.

In this study, we intend to develop a control valve with oxidation resistance for hydrogen fluoride that can be applied to the semiconductor production process. Operated Valves currently in use is a form of assembling an air cylinder to the valve body. These valves generally have a cylinder body made of aluminum (Al), so they may corrode depending on the external environment, and the solution leaks along the rod inside the cylinder, causing damage to parts due to corrosion. To solve this problem, the valve plug shape was developed by devising and applying a plug using a valve different from the existing method, and it is possible to block the inflow of hydrogen fluoride into the valve control unit, thereby preventing damage to parts as well as maintaining stable valve operation.

Valves are one of the indispensable components in modern industry. Filling and de-pressure connectors in rocket valves used for space launch vehicles are very important parts for smooth fluid supply. For this reason, an optimized design that can improve efficiency, miniaturization, weight reduction, and safety of the valve at the same time is required. In this work, flow analysis and structural analysis were performed through 3D modeling using computational numerical analysis for open type filling and de-pressure valves. As results, the flow velocity and pressure distribution of the fluid were analyzed through the flow analysis of valve, and stress distribution was conducted in structural analysis. Through this study, it is consequently expected to provide valves of various specifications by performing production and performance test evaluation of development prototypes.

밸브의 내부 누설 현상은 밸브의 내부 부품의 손상에 의해 발생하며 배관 시스템의 사고와 운전정지를 일으키는 주요 요인이 다. 본 연구는 버터플라이형 밸브의 내부 누설에 따라 배관계에서 발생하는 음향방출 신호를 이용하여 배관 가동 중 실시간 누설 진단의 가능성을 검토하였다. 이를 위해 밸브의 작동 모드별로 측정한 시간영역의 AE 원시신호를 취득하였으며 이로부터 구축한 데이터셋은 데 이터 기반의 인공지능 알고리즘에 적용하여 밸브의 내부 누설 유무를 진단하는 모델을 생성하였다. 누설 유무진단을 분류의 문제로 정의 하여 SVM 기반의 머신러닝과 CNN 기반의 딥러닝 분류 알고리즘을 적용하였다. 데이터의 특징 추출에 기반한 SVM 분류 모델의 경우, 이 진분류 모델에서 구축된 모델에 따라 83~90%의 정확도를 나타냈으며, 다중 클래스인 경우 분류 정확도가 66%로 감소하였다. 반면, CNN 기반의 다중 클래스 분류 모델의 경우 99.85%의 분류 정확도를 얻을 수 있었다. 결론적으로 밸브 내부 누설 진단을 위한 SVM 분류모델은 다중 클래스의 정확도 향상을 위해 적절한 특징 추출이 필요하며, CNN 기반의 분류모델은 프로세서의 성능 저하만 없다면 누설진단과 밸브 개도 분류에 효율적인 접근방법임을 확인하였다.

The Calorifier is a device that supplies hot water to the crew for showering and cooking. In particular, problems such as hot water not coming out when a trainee and a crew member take a shower at the same time may occur due to a malfunction of the temperature control valve that controls the temperature. In particular, when the hot water usage time is almost constant, such as a training ship, a high calorific value is required. When there is no dissatisfaction with the use of hot water, satisfaction with the educational environment is improved. Therefore, in this study, a solenoid temperature control valve is applied to increase satisfaction with hot water use, and a mechanical time switch is applied to the hot water circulating water pump to save energy.

A 19-year-old male Siberian tiger was presented with inappetence and paralysis of hind limbs. In a computed tomography (CT) scan, intervertebral disk disease at L3–L4 was detected. Cardiac arrest occurred during the surgery. At autopsy, myxomatous mitral valve degeneration (MMVD) and eccentric hypertrophy of the left heart were noted. The diagnosis was congestive heart failure caused by MMVD. Microscopically, myocardial and pulmonary fibrosis were observed in addition to the disintegration of the fibrosa layer and accumulation of glycosaminoglycans and proteoglycans in the spongiosa layer of the mitral valve. This is the first case of congestive heart failure with MMVD in a Siberian tiger.

Butterfly valves have been used to control the flow rate of various fluids in many industries because it have unique manageability compare to other valves. However, when a defect occurs due to the failure of the backlash of the power transmission part and the pin breakage of the butterfly valve due to the absence of the design capability of the valve, it is difficult to analyze the cause and maintain it. In this paper, a study was conducted to secure the reliability of the valve by performing structural analysis and analysis using a 3D model of the product to manufacture a high-quality valve.

In this study, a method of leakage detection was proposed to locate leak position for a reservoir pipeline valve system using wavelet coherence analysis for an injected pressure wave. An unsteady flow analyzer handled nonlinear valve maneuver and corresponding experimental result were compared. Time series of pressure head were analyzed through wavelet coherence analysis both for no leak and leak conditions. The leak information can be obtained through either time domain reflectometry or the difference in wavelet coherence level, which provide predictions in terms of leak location. The reconstructed pressure signal facilitates the identification of leak presence comparing with existing wavelet coherence analysis.