• 한국환경과학회지
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• 제25권8호
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• pp.1191-1206
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• 2016

Transported deposit was accumulated in a grit chamber built at the mouth of Yeocheoncheon in 1987 with the intention of blocking the influx of sediment into the Ulsan-harbor. This study attempted to analyze the effects of the transported deposit on the water quality at Yeocheoncheon. Only one episode of dredging has been performed in the approximately 25 years since the grit chamber were built, leading to the formation of stagnant water in the grit chamber due to a large amount of transported deposit. The deposit has a relatively high organic content, in the range of 11.7-25.9% (mean 18.3%). It appears that the main reason for the upstream transport of water pollution from the mouth of the Yeocheoncheon is the tides. The effects of organic content and stagnant water on water quality were analyzed using WASP. Moreover, the changes in water quality arising due to the removal of the grit chamber were analyzed. Results indicated that BOD improved by 18.8-100%, while T-P improved by 90.0-617.4%, between the grit chamber and Hanbi-Gyo, which is located 1.3 km away from the grit chamber.

• 한국의학물리학회지:의학물리
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• 제9권1호
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• pp.29-35
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• 1998

There has been necessity of an air free ionization chamber using the gold-crystal-aluminium plates, henceforth called the crystal chamber. The crystal chamber formed of parallel plates is very small in size and has more response for absorbed dose of therapeutic radiation beams. The gold plate on the crystal facing the photon and electron beam acts as an intensifier of signals and crystal plate as an ionization medium respectively. Both the copper guard ring and the aluminum collecting electrode are connected to an electrometer. Using high energy photon (6, 15 MV) and electron (9, 12, 15, 18 MeV) beams, the responses of the crystal chamber are evaluated against a PTW Farmer-type chamber at a field size of 10${\times}$10cm$^2$ and 100 cm SSD. The responses of crystal chamber for therapeutic radiation electron and photon beams are greater in magnitude by several order than Farmer. The crystal chamber has good linearity without correction factor C$\_$t,p/ with respect to the signals, a reading reproduction with good accuracy and precision less than 0.5%, and has other useful functions in measuring radiation beams.

• 건축역사연구
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• 제31권4호
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• pp.57-70
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• 2022

The Joseon royal family considered the act of burying the placenta very important for various reasons. Accordingly, they developed their own ritual culture of burying the placenta based on the geomancy(Pungsu). In 1661, The King Sukjong's placenta chamber was built in Gong-ju, and later stone objects were added in 1683. Since its establishment, the King Sukjong's placenta chamer have been continuously managed by the Joseon royal family, but During the Japanese colonial period, the placenta chamber was partially destroyed, and now only some stone objects remain in the original site. This study aims to estimate the original style and structure of King Sukjong's placenta chamber by focusing on the stone objects which were discovered through recent field surveys. In addition to that, the stylistic review of Joseon Dynasty's royal placenta chamber was conducted to secure a literary data basis and acquired data were comprehensively analyzed. As a result, Some of the original style and structure of King Sukjong's placenta chamber could be confirmed. The results of this study are expected to help restore the authenticity of the royal placenta chamber damaged in japanese colonial period, and are expected to be a good example in the research methodology of historical evidence of other damaged royal placenta chambers.

• 한국생산제조학회지
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• 제26권4호
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• pp.387-394
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• 2017

This paper develops a pump system for patient with chronic pain or cancer. The pump module is consists of two micro-valve and membrane. The micro-valve is operated by a solenoid. With two solenoid valves which are connected via a drug transport line, the inlet and outlet are completely blocked. A silicon rubber membrane located between the two valves makes the flow-rate constant without any backflow. This pump module can control the flow-rate of drugs by controlling the time that the valves are opened and closed. The reservoir consists of a drug chamber and a gas chamber. As the gas chamber encloses the drug chamber, propellant gas which is injected into the gas chamber pressurizes the drug chamber regardless of volume of the drug chamber. To design the pump module, analysis a constant efficiency test, and accuracy test for the pump module were conducted.

• 한국연소학회지
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• 제2권1호
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• pp.17-27
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• 1997

It is well known that NOx formation has a strong dependence on the maximum temperature and correspondingly with the maximum chamber pressure of a closed combustion system. However, in a case of impinging-jet-flame (IJF hereafter) combustion with opposed dual pre-chambers, low $NO_x$ formation with high pressure could be achieved, but its mechanism has not been clearly understood so far. In this study, a three-dimensional analysis is adopted to resolve time-variant local properties that might indicate the mechanism of IJF combustion. Numerical results are verified by comparing them with experiments. The IJF combustion in a vessel with no pre-chamber, with single pre-chamber, and with dual pre-chambers is studied. The orifice diameter and the volumetric ratio of pre-chamber are used as geometric parameters. The effects of main-chamber ignition delay time and combustion time of main-chamber, orifice exit velocity, orifice exit temperature, turbulent kinetic energy of main-chamber and spatial distribution of temperature in the latter stage of combustion are investigated. A longer main-chamber ignition delay and a shorter main-chamber combustion time suppress the formation of high temperature region with respect to mean temperature, which consequently results in less NO production.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.890-895
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• 2001

Pressure resonance frequency that is caused in the combustion chamber can be interpreted to acoustic analysis. Until now the pressure resonance has been assumed and calculated to a disc type combustion chamber that neglected the combustion chamber height because the knock occurs near the TDC(top dead center). In this research FEM(fine element method) has been used to calculate the pressure resonance frequency inside the experimental engine combustion. The reduce error of the resonance frequency obtained by FEM has decreased about 50% compared to the calculation of Draper's equation. Due to the asymmetry in the shape of the combustion chamber that was neglected in Draper's equation we could find out that a new resonance frequency could be generated. To make the experimental results equal we could know that the speed of sound that satisfies Draper's equation was selected 13% higher than all the pent-roof type combustion considered.

• 대한기계학회논문집
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• 제17권10호
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• pp.2611-2623
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• 1993

To construct the design back data for a lean-burn gas engine, we investigated the combustion characteristics in the main chamber using a constant volume combustion chamber with subchamber. The combustion characteristics with configuration change of the critical passageholes have been studied by taking pressure data, schlieren photograph, ion current and light emission signal of flame. Heat release rate with various critical passageholes also have been analysed by using the combustion model of a prechamber diesel engine. It was found that combustion characteristics in the main combustion chamber were greatly influenced by the geometric configurations of critical passagehole.

• 한국자동차공학회논문집
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• 제8권1호
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• pp.48-53
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• 2000

The effects of the internal flow in a diesel injection nozzle on the atomization of the spray has been investigated experimentally. Flow visualization was made using a transparent acrylic model nozzle. And also, measurement of the sac chamber pressure was made for clartfying the effect of pressure fluctuation in the sac chamber on the wpray behaviors. The geometry of the model nozzle was scaled up 10 times of the actual nozzle and the injection pressure for the model nozzle was adjusted so as to achieve a Reynolds number at the discharge hole which was the same as the actual nozzle. Polystyrene tracers, a laser sheet light and a still/high speed video camera were used to visualize the flow pattern in the sac chamber. When the needle lift was small, the high turbulence in the sac chamber generated by the high velocity seat flow made the spread angle of the spray large. Cavitation which arose in the sky chamber induced the pressure fluctuation and then affects the spread angle of the spray.

• 한국항공우주학회지
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• 제31권4호
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• pp.76-81
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• 2003

Kerosene/LOX를 추진제로 사용하는 액체로켓의 추력실에서 발생하는 열유속을 측정하기 위하여 calorimetric combustion chamber를 제작하여 연소실험을 수행하였다. 본 실험에 사용된 calorimetric combustion chamber는 연소실 및 노즐 부분이 각각 하나의 구역으로 제작되었으며, 각각의 구역에서 발생하는 열유속을 측정하기 위하여 냉각제의 출구에 열전대를 설치하였다. 실험은 O/F ratio 2.0에서 연소압 100psi에서 300psi까지 수행하였다. 본 실험에서 연소실에서 복사 열전달은 고려하지 않았다. 측정된 열유속은 연소압에 다라 거의 선형적인 변화를 보였다.

• 한국가스학회지
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• 제20권4호
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• pp.44-49
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• 2016

본 연구는 연소실 형상 변화에 따른 디젤연소와 배출가스의 특성에 대해 살펴보았다. 발전용 커먼레일 디젤엔진의 최적화 설계를 위한 연소실형상을 제시하기 위해 5가지 타입형상을 연비 측면에서 계산하였다. 연소실 형상은 연소 시 분무면적을 변화시킴으로서 연소특성에 영향을 주었으며 이러한 주요요소는 연소실 형상 비였다. 이러한 수치해석의 결과는 연소실 형상의 변화는 발전기의 연비 개선을 가능하도록 한다고 판단되었다.