• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2006년도 제27회 추계학술대회논문집
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• pp.43-46
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• 2006

축열식 가열기는 주로 초음속 지상추진 시험설비의 고고도 조건 모사를 위하여 구축되는 장비로 이외에도 로켓 엔진 노즐의 추력 보정시험, 가스터빈 엔진 연소기 모사시험에 범용으로 사용할 수 있다. 한국항공우주연구원에서 보유하고 있는 축열식 가열시스템은 마하 $2{\sim}5$, 고도 $0{\sim}25km$의 범위에서 구동하는 초음속 지상추진시험설비의 전온도 모사를 목적으로 설계되었으며, 최고 모사 온도 1,300 K, 최고 가압압력 3.5 MPa의 성능을 낸다. 본 논문에는 본 원에서 구축한 축열식 가열기의 목표로 한 일본 JAXA RJTF에 구축되어있는 축열식 가열기에 대하여 정리하도록 한다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권6호
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• pp.46-52
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• 2010

Derivative analysis, based on the derivative of the drawdown as a function of time (i.e., rate of drawdown change), was applied to the evaluation of hydraulic parameters of the aquifer as an aid of the aquifer test interpretation based on the Theis solutions. Pumping tests were conducted at a coastal fractured aquifer in Muan county, Korea, of which the drawdown data, measured at the two observation wells, were used for derivative analysis. Wellbore storage and transition period were hard to identify at conventional log-log and semi long plots, but was easily recognized by distinctive curves of positive unit slope, hump and negative unit slope in the derivative plot. For the observation well of OW-2 at which wellbore storage and transition lasted over an hour, conventional aquifer analysis would suffer from the uniqueness problems and in further result in erroneous hydraulic parameters. Derivative analysis was found to be effective for distinguishing the drawdown data directly reflecting the aquifer property from those reflecting non aquifer effects such as wellbore storage and transition, which offers a unified methodology to yield correct hydraulic parameters from aquifer test data.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.517-522
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• 2005

A cold storage refrigerator using phase change material(PCM) has been developed and its performance test results are provided here. The inner temperature of the refrigerator is controlled with forced convection driven by a fan using a DC battery. At the first, to freeze all the PCM of the ambient temperature by a built-in refrigerating machine, it took about 8 and 10 hours respectively at the refrigerator and the freezer mode. Then, without external power supply, the inner temperature of the cold storage refrigerator has been maintained at $-18{\pm}1^{\circ}C$ during 14 hours at the freezer mode and maintained at $3{\pm}^{\circ}C$ during 34 hours at the refrigerator mode. Just after the end of its valid usage as a refrigerator or a freezer, it took about 6 hours to refreeze the PCM for its reuse. During the test, the ambient temperature was kept at $30^{\circ}C$.

• 설비공학논문집
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• 제20권2호
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• pp.97-105
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• 2008

This paper presents simulated and experimental test results of optimal control algorithm for an encapsulated ice thermal storage system with full capacity chiller operation. The algorithm finds an optimal combination of a chiller and/or a storage tank operation for the minimum total operation cost through a cycle of charging and discharging. Dynamic programming is used to find the optimal control schedule. The conventional control strategy of chiller-priority is the baseline case for comparing with the optimal control strategy through simulation and experimental test. Simulation shows that operating cost for the optimal control with chiller on-off operation is not so different from that with chiller part load capacity control. As a result from the experimental test, the optimal control operation according to the simulated operation schedule showed about 14 % of cost saving compared with the chiller-priority control.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.479-484
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• 2005

The test blasts were carried out by detonating some single blastholes at two upper sites of the underground storage cavern the crude oil. One was performed at the entrance site of the construction tunnel and the other at the middle part of the underground storage cavern. Based on the blast-induced vibration measured by the test blasts, we suggested the propagation equations of blasting vibration that were capable of estimating the peak particle velocity. In addition, in order to assess the stability of the nearest ground storage tank, we did the frequency analysis and the response spectrum analysis with the particle velocity-time history and the particle acceleration-time history that were measured by the test blast carried out on the entrance site of the construction tunnel. In result, it was predicted that the displacement on the highest part of the tank shell was less than the allowable displacement.

• 한국식품조리과학회지
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• 제17권2호
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• pp.149-155
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• 2001

Namul cooked with the standard recipe was examined by research of microbiological test for three months and sensory evaluation of frozen namul after reheating. When the namul was freezed storage, in the microbiological test namul began to change on the 40th day, but there was no problem about stability of storage until 3 months. The overall qualities of taste, flavor, color and texture were examined by sensory evaluation of frozen namul after reheating. The pH was seemed to change slowly, its color was changed on the 20th day from the beginning of storage. Radish root represented substantial difference in texture and overall quality on the 20th day. The off-flavor of immature pumpkin stated on the 25th day. Later 10days nettle tree mushroom began to be changed in its taste, texture, overall quality and appearance, then on the 25th day it was seemed to have low preference. But oak mushroom kept its quality good for 25 days. Oyster mushroom was changed in color, appearance and overall quality on the 20th day. Bracken had low preference in taste, texture and moisture on the 25th day. The color of spinach was changed on the 15th day, and its taste on the 20th day. Soybean sprout was changed in taste, texture and overall quality on the 15th day, and overall quality marked low preference on the 25th day Root of bell flower was changed on the 25th day(p<0.05).

• Structural Engineering and Mechanics
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• 제83권6호
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• pp.745-756
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• 2022

This study aims to determine the cause of the load resistance loss in storage racks that can be attributed to external forces such as earthquakes and to improve safety by developing reinforcement systems that can prevent load resistance loss. To this end, a static cyclic loading test was performed on pallet racks commonly used in logistics warehouses. The test results indicated that a pallet rack exposed to an external force loses more than 50% of its load resistance owing to the damage caused to column-beam joints. Three reinforcement systems were developed for preventing load resistance loss in storage racks exposed to an external force and for performing differentiated target functions: column reinforcement device, seismic damper, and viscoelastic damper. Shake table testing was performed to evaluate the earthquake response and verify the performance of these reinforcement systems. The results confirmed that, the maximum displacement, which causes the loss of load resistance and the permanent deformation of racks under external force, is reduced using the developed reinforcement devices. Thus, the appropriate selection of the developed reinforcement devices by users can help secure the safety of the storage racks.

• 한국자동차공학회논문집
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• 제22권2호
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• pp.60-66
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• 2014

A control oriented model of the Lean $NO_x$ trap (LNT) was developed to determine the timing of $NO_x$ regeneration. The LNT model consists of $NO_x$ storage and reduction model. Once $NO_x$ is stored ($NO_x$ storage model), at the right timing $NO_x$ should be released and then reduced ($NO_x$ reduction model) with reductants on the catalyst active sites, called regeneration. The $NO_x$ storage model simulates the degree of stored $NO_x$ in the LNT. It is structured by an instantaneous $NO_x$ storage efficiency and the $NO_x$ storage capacity model. The $NO_x$ storge capacity model was modeled to have a Gaussian distribution with a function of exhaust gas temperature. $NO_x$ release and reduction reactions for the $NO_x$ reduction model were modeled as Arrhenius equations. The parameter identification was optimally performed by the data of the bench flow reactor test results at space velocity 50,000/hr, 80,000/hr, and temperature of $250-500^{\circ}C$. The LNT model state, storage fraction indicates the degree of stored $NO_x$ in the LNT and thus, the timing of the regeneration can be determined based on it. For practical purpose, this model will be verified more completely by engine test data which simulate the NEDC transient mode.

• 한국식품저장유통학회지
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• 제6권4호
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• pp.376-379
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• 1999

만생종 중립계 포도에 대한 저장성을 검토하기 위해 재배면적이 많은 Sheridan, Tano Red 및 Muscat Bailey A 등 3품종을 공시하여 저장전 SO$_2$훈증처리, 저장온도 $0^{\circ}C$, 습도 90% RH의 조건에서 polyethylene film으로 밀봉하여 저장성을 시험하였다. 중량 감소는 저장기간이 경과할 수록 많았으며, Sheridan 품종이 감소의 정도가 가장 적었다. 비정상과는 저장기간이 경과할수록 많았고, 저장 90일 이후 급격히 증가하여 상품성이 저하되었으며, 135일 저장 시 Sheridan

• 한국군사과학기술학회지
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• 제14권5호
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• pp.888-896
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• 2011

A white smoke hand grenade, KM8 is used to make smoke screen in order to provide visual field interceptions or signals. The grenade fails when its time to emit smoke is longer than the specified emission time so that the smoke concentration becomes lighter. This paper considered failure in smoke emission time, and evaluated its storage lifetime. The main objective of this paper is to modify the present specification limits of smoke emission time for the efficient process control in manufacturing, through analyzing effect of its specification change on the storage lifetime, based on the lifetime evaluation results. Accelerated degradation test was performed and then failure in smoke emission time was reproduced from the test. And estimated storage lifetimes from the accelerated test results was compared to evaluated lifetimes of grenades using the ASRP data. Past process testing results of the grenade in manufacturing were analyzed in this paper. Then, each storage lifetime for the specifications, ${\pm}3$ and ${\pm}5$ in seconds, extended from the current specification in manufacturing were estimated using the past testing results, and compared to one another.