• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.1035-1040
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• 2003

This research investigates the actual data and construction technology of the massive bottom slab placed by $23,000m^3$ concrete quantity in site of the in-ground type LNG receiving terminal having 20,000kl storage capacity. The purpose of this study is to determine the optimum mix design and control the actual concreting procedures including concrete production, transportation, placement, vibrating and curing in site. For this purpose, the optimum mix design using ternary blended cement(furnace slag cement＋fly ash) and under piping method having 11 gates and 7 distributors are selected. As test results of actual construction, concrete placement is finished during 68hours with good success and obtained the good quality of the fresh and hardened concrete including slump, air contents, no-segregation, compressive strength and low hydration heat. Also, actual data for all of concrete procedures are proved successful and satisfied with our specifications.

• Nuclear Engineering and Technology
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• v.53 no.11
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• pp.3837-3851
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• 2021

To investigate how the fabrication and repair of socket welded joints could be used to enhance fatigue resistance under vibration condition, experimental test data of installation conditions that potentially influence fatigue strength were analyzed with the S-N curve. It was found that the decreasing fatigue strength of stainless steel socket welded joints was attributed to the effect of high heat input of welding process. The effect of welding method, slip-on gap and radial-gap conditions on fatigue strength was insignificant. The test data of repair technique application, 2 × 1 leg length and of socket weld overlay, clearly showed higher fatigue strength but there was a limitation for higher stress region because of the weld toe crack.

• Proceedings of the Korean Information Science Society Conference
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• 2007.10d
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• pp.431-434
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• 2007

국내외 방송환경이 디지털로 급속히 변화함에 따라서 지상파, 케이블, 위성 등의 기존 방송망을 이용하며 서비스 제공자가 제공하는 데이터 서비스를 사용자가 요청 할 때 전송하는 데이터 방송은 기존의 비디오, 오디오 방송 프로그램 이외에 방송과 관련된 데이터 또는 방송과는 직접 관련이 없는 순수한 데이터를 제공하게 되었다. 데이터 방송 표준 단체인 DVB(Digital Video Broadcasting)에서는 데이터 방송 시 데이터 전송 기법으로 데이터 스트리밍(Data Streaming), 데이터 파이핑(Data Piping), 데이터 캐루셀(Data Carousel), 멀티프로토콜 인캡슐레이션(Multiprotocol Encapsulation), 객체 캐루셀(Object Carousel)을 제안하고 있다. 본 논문에서는 데이터 방송에 사용되는 데이터를 효율적으로 관리하기 위하여 메시지 캐슁과 모듈 캐슁을 기반으로 한 데이터 캐루셀 매니저 설계와 구현에 관한 내용을 다룬다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.20-29
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• 2018

Owing to the changing climate and recent flood events, flood damage caused by river levee collapse and overflow is on the rise in Korea, making it necessary to enhance river levee maintenance technologies to deal with various flood damage scenarios. This paper proposes the evaluation system of a river-levee safety map to improve maintenance efficiency and disaster responsiveness. A river-levee safety map, indicating sliding, piping, visual inspection, scouring, and safety index of a levee fill material on a GIS map will enable the dangerous zone to be identified visually and the development of proactive measures to deal with it. This will maximize the river-levee maintenance efficiency, which is a break from traditional practice in that restoration measures are taken only after the damage has occurred. This study includes scouring and levee fill material in addition to previously-proposed sliding, piping and visual inspections. The research activities conducted in the study include 1) categorization of scouring and levee fill material based on document and data examination, 2) evaluation of sliding and piping at 5 locations on the left levee in the Nam river according to the duration time of the flood water level, and 3) evaluation of the characteristics of scouring and levee fill material at 9 locations on the left/right levee in the Nam River. The river levee safety map proposed in this study would be more useful and practical but further study on the manual for river management organization, repair and reinforcement methods, and budget is required.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.2
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• pp.179-184
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• 2009

The Fuel Test Loop(FTL) which is capable of an irradiation testing under a similar operating condition to those of PWR(Pressurized Water Reactor) and CANDU(CANadian Deuterium Uranium reactor) nuclear power plants has been developed and installed in HANARO, KAERI(Korea Atomic Energy Research Institute). It consists of In-Pile Section(IPS) and Out-of Pile System(OPS). The IPS, which is located inside the pool is divided into 3-parts; the in-pool pipes, the IVA(IPS Vessel Assembly) and the support structures. The test fuel is loaded inside a double wall, inner pressure vessel and outer pressure vessel, to keep the functionality of the reactor coolant pressure boundary. The IVA is manufactured by local company and the functional test and verification were done through pressure drop, vibration, hydraulic and leakage tests. The brazing technique for the instrument lines has been checked for its functionality and performance. An IVA has been manufactured by local technique and have finally tested under high temperature and high pressure. The IVA and piping did not experience leakage, as we have checked the piping, flanges, assembly parts. We have obtained good data during the three cycle test which includes a pressure test, pressure and temperature cycling, and constant temperature.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.886-892
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• 2013

Hydraulic hose assemblies are used as piping components for construction machinery, automobile, aircraft, industrial machinery, machine tools, and machinery for ships. Then the reliability of hose assemblies is important because total hydraulic system, which used to deliver the fluid power ($P^*Q$) needed to flexibility in the piping system, is not operated if the hose assembly failed in the system. The data of the accelerated life test estimated through the shape parameter(${\beta}$) resulting of the Weibull distribution analysis. This study has tried to reduce the test time resulting from varying impulse pressure range and the flexing diameter. Accelerated life test model for the test results was adopted the GLL(generalized log linear) and the accelerated indexes are identified as 6.64 for the pressure and 4.46 for flexing radius. Also, it found that shape parameter is 6.19, scale parameter(${\eta}$) is $1.035{\times}108$, which were adopted the pressure 35 MPa and the flexing diameter R100 mm in the used condition.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.1
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• pp.20-24
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• 2015

Steam generator(S/G) tubes in pressurized water reactor (PWR's) are subject to several types of degradation. This degradation includes denting, pitting, intergranular attack(IGA), intergranular stress corrosion cracking(IGSCC), fatigue, fretting and wear. Degradation can be derived from either the primary side(inside) or the secondary side(outside) of the tube. Recent issue for tube degradation in domestic steam generator is the tube end cracking on seal weld region. The seal weld region at the tube end and tube itself is regarded as a pressure boundary between the primary side and the secondary side. One of the Westinghouse Model-F S/G has experienced tube end cracking and its number of plugging approximately becomes to the operating limit up to 5% due to tube end cracking which was reported as SAI/MAI(single/multiple axial indication) or SCI/MCI(Single/multiple circumferential indication) from the results of eddy current testing. Eddy current mock-up test was carried out to determine the origin of cracking whether it is from weld zone area or parent tube. This result was helpful to analyze crack location on ECT data. Correct action on this problem was the installation of tube-end sleeve. Last year, after removing 340 installed plugs from tubes, selected 269 tubes took tube-end sleeve installation. Tube-end sleeve brought pressure boundary from parent tube to installed sleeve tube. Tube-end sleeve has the benefit of reducing outage period and increasing more revenue than replacing S/G. This paper is provided to assist interest parties in effectively understanding this issue.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.8 no.2
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• pp.14-20
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• 2012

Full load rejection capability of nuclear power plant depends primarily on steam dump capacity (SDCAP) and steam generator level control capability. Recently, Ulchin Units 1&2 have performed stretched power uprate (SPU) and replacement steam generator (RSG) projects, which increase the power by 4.5 percent. They change major design or operating parameters and especially reduces steam dump capacity at full power due to increase of the steam flow. The reduction of SDC after SPU results in degradation of heat removal capability in full load rejection transients. Therefore, we should perform evaluation to determine whether reactor trips occur in large load rejection transients. Uchin Units 1&2 have experienced full load rejection (FLR) three times from 2004 to 2010. Operating data from the plant occurrence of FLR at Ulchin Units 1&2 showed that steam generator (SG) level transients were limiting in point of reactor trip. However the plant had never reached reactor trip in the FLR and successfully continued in house load operation. The parameters and setpoints for the SG will be changed if the SG is replaced. Therefore, we evaluated the appropriateness of steam dump, main feedwater and steam generator water level control system preventing the plant from reactor trip in case of FLR by the parameter sensitivity study whether SG water level operated smoothly after SPU and RSG projects.

• Fire Science and Engineering
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• v.30 no.4
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• pp.46-58
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• 2016

In this study, the stress applied to screw section, strain, displacement, von Mises stress, and the compression stress applied to the rubber packing for watertightness are estimated with computer simulation when the tightening torque of valve socket is in the range of $10{\sim}130N{\cdot}m$ in order to analyze the influence of valve socket screw section in accordance with the excessive tightening which is supposed to be the cause of water leakage from the synthetic resin piping for fire fighting application of sprinkler equipment, and for the sake of verifying this, adequate value of tightening torque and the value of the compression stress of rubber packing are investigated by examining the number of connected thread for each tightening torque, the deformation state of valve socket and rubber packing and conducting the water hammering test. The result of this test is expected to be utilized as the data required for revising the standard or technical criteria to prevent the water leakage of the synthetic resin piping for fire fighting application.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.4 no.2
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• pp.40-45
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• 2008

There exist many types of pipe and component fatigue through vibrations, thermal fatigues or shifting. In some cases of thermal stratification/thermal fatigue, pipes & components are receiving thermal stress by means of material expansion and shrinkage by continuous thermal repetitive variation. Small cracks initially occur on the inside surface by thermal stress. These cracks grow in depth the pipe wall and finally come to a rupture. Pipe parts of susceptibility to thermal stratification and thermal fatigue are now being examined by conventional UT(ultrasonic test) as volumetric examination. It is difficult to fully satisfy the code & standards requirements because 3" weldolet weldments of RCS 16" pipe to 3" branch connection lines have complex structural shape. To solve the problems of conventional UT examination, we made a realistic mock-up and UT calibration block. We performed a simulation of phased array UT utilizing CIVA as NDE(Non-Destructive Examination) simulation software. Also we designed phased array UT transducer and wedge, optimal frequency by using simulation data. We performed phased array UT experiment through mock-up including artificial flaws(notch). The phased array UT technique is finally developed to improve the reliability of ultrasonic test at RCS 16" pipe to 3" branch connection weld.