Cars using diesel have always had problems with reducing exhaust fumes, and have been studied steadily in this regard. There were studies on the remanufacturing effect of DOC catalyst deactivated by diesel vehicle smoke reduction device, analysis of vehicle fire accident cases caused by damage to diesel vehicle smoke reduction device, and related studies on the remanufacturing effect of diesel vehicle smoke reduction device DPF. This study is also to develop a burner structure in a smoke reduction device suitable for an exhaust engine to completely burn smoke generated by an engine using a diesel engine in a low-temperature exhaust gas. The main systems to be developed are high-performance heaters, burner structures that can maintain ignition in exhaust flows, and exhaust flow control units that reduce exhaust gas backflow effects caused by diesel engines.

This study investigates the melting point and brazing properties of the aluminum (Al)-copper (Cu)-silicon (Si)-tin (Sn) alloy fabricated for low-temperature brazing based on the alloy design. Specifically, the Al-20Cu-10Si-Sn alloy is examined and confirmed to possess a melting point of approximately 520oC. Analysis of the melting point of the alloy based on composition reveals that the melting temperature tends to decrease with increasing Cu and Si content, along with a corresponding decrease as the Sn content rises. This study verifies that the Al-20Cu-10Si-5Sn alloy exhibits high liquidity and favorable mechanical properties for brazing through the joint gap filling test and Vickers hardness measurements. Additionally, a powder fabricated using the Al-20Cu-10Si-5Sn alloy demonstrates a melting point of around 515oC following melting point analysis. Consequently, it is deemed highly suitable for use as a low-temperature Al brazing material.

PURPOSES : The numeric-based Highway Pavement Management System (HPMS), along with an advanced three-dimensional pavement condition monitoring profiler vehicle (3DPM), in South Korea has presented remarkable advancements in pavement management since the early 2000. Based on these results, visual distress on pavement surfaces can be easily detected and analyzed. Additionally, the entire expressway pavement surface conditions in South Korea can be easily monitored using the current graphical user interface-based advanced information graphic (AIG) approach. Therefore, a critically negative pavement section can be detected and managed more easily and efficiently. However, the actual mechanical performance of the selected pavement layer still needs to be investigated in a more thorough manner not only to provide more accurate pavement performance results but also to verify the feasibility of the current 3DPM and AIG approaches. In this study, the low-temperature performance of the selected asphalt pavement layer section was evaluated to further verify and strengthen the feasibility of the current 3DPM and AIG approaches developed by the Korea Expressway Corporation. METHODS : Based on 3DPM and AIG approach, the positive and negative-riding-quality road sections were selected, respectively. The asphalt material cores were extracted from each section then bending beam rheometer mixture creep test was performed to measure their low-temperature properties. Based on the experimental results, thermal stress results were computed and visually compared. RESULTS : As expected, the asphalt material from the negative driving performance section presented a poorer low-temperature cracking resistance than that from the positive driving performance section. CONCLUSIONS : Current 3DPM equipment can successfully evaluate expressway surface conditions and the corresponding material performance quality. However, more extensive experimental studies are recommended to verify and strengthen the findings of this study

In this study, numerical modeling on the gas flow and off-gases in the low temperature carbonization furnace for carbon fiber was analyzed. The furnace was designed for testing carbonization process of carbon fibers made from various precursors. Nitrogen gas was used as a working gas and it was treated as an incompressible ideal gas. Three-dimensional computational fluid dynamics for steady state turbulent flow was used to analyze flow pattern and temperature field in the furnace. The off-gas mass fraction and cumulative emission gas of species were incorporated into the CFD analyses by using the user defined function(UDF). As a results, during the carbonization process, the emission of CO2 was the dominant among the off-gases, and tow moving made the flow in the furnace be uniform.

홍삼의 일반적인 가공법인 물과 주정 혼합용매로 추출여과하여 농축액으로 제조 시 증숙 등의 가열처리에 의해 가수분해되거나 중합반응이 일어나게 되어 현재 기능성이 밝혀진 30여 가지 주요 진세노사이드 외 극미량인 200여 종의 진세노사이드가 검출되고 있어서, 오히려 홍삼 본래 의 기능성 규명과 효능 구현을 복잡하게 만들고, 추출 횟 수를 거듭할수록 떫은맛이 강해지는 등 건강기능식품으로 서 부정적인 영향을 배제하기 위하여 저온(40oC 미만)에 서 1차만 추출한 홍삼농축액을 제조한 결과 수율은 고형 분 66-77% 정도에서 26-30%를 나타내어 기존의 연구 결 과인 40.47±0.47% 보다 현저히 적은 수율을 나타내었고, 동결건조 분말의 진세노사이드 함량분석시험을 진행한 결 과 시료 18종 전체에서 진세노사이드 34종이 검출되었고, 특히 홍삼 지표성분 3종인 Rb1, Rg1, Rg3 합계는 42.48 mg/ g으로 시판 홍삼제품의 환산량 9.0 mg/g과 8.7 mg/g 보다 4-5배 많았다. 본 시료는 진한 홍삼의 향취와 함께 면역력 증진 등 6가지 기능발현에 9-25%의 소량 복용으로 1일 복 용량이 유의성 있게 작아서 복용의 편의성과 함께 제품의 보관, 유통에 장점이 있는 것으로 판단된다.

With the development of drone technology, drones are being used in various industries. In general, drones use lithium-based battery pack, which is sensitive to external impact and temperature characteristics. Therefore, in order to prevent this problem, a battery case for protecting the battery from the outside is used. Usually, carbon fiber is used as case material, carbon fiber is expensive and has disadvantages of being difficult to manufacture. In this study, a battery case was fabricated to minimize the influence of external impact and temperature by using expanded polypropylene material, and also the battery efficiency test was performed using fabricated case. After basic design for battery case was conducted, a system capable of maintaining temperature was constructed by attaching a surface heating element inside the case, and the effect of maintaining temperature according to the presence or absence of the case was confirmed. Using manufactured prototype case, flight tests were carried out to check the battery voltage level according to the presence or absence of the case and to analyze the effect of improving the battery efficiency for the flight time of the drone.

본 연구는 저염분 상태에서 수온 및 사육밀도와 같은 환경요인이 흰다리새우(Litopenaeus vannamei)의 성장에 미치는 영향을 조사하기 위하여 수행하였다. 연구 결과, 흰다리새우는 저 염분 상태에서 전반적으로 수온이 높을수록 생존율이 높게 나타났고, 사육밀도가 낮을수록 생 존율이 높아졌다. 사료효율에 관한 연구에서는 수온이 높을수록 증체량(WG)이 증가하였고, 사 육밀도가 증가할수록 증체량은 감소하였다. 수온이 높을수록(수온 31℃) 성장 속도가 빨랐다. 또한 사육밀도에 따른 성장도의 평가에서도 사육밀도가 낮은 상태에서 성장 속도가 빨라지는 것을 확인하였다. 본 연구 결과를 흰다리새우의 최적 성장을 위한 적정 사육밀도 및 사육수온 의 결정에 유용하게 적용되리라 사료된다.

대표적인 비구조요소인 배관의 지진에 의한 손상은 관성력과 두 지지점 사이의 위상차에 의해 작용하는 반복하중 그 리고 허용변형량을 초과하는 상대변위 등에 의해 발생할 수 있다. 특히 주요 손상모드는 큰 반복하중에 의한 저주기피로임이 많은 실험적 연구를 통하여 알려졌다. 따라서 과도한 지진변위에 의한 배관의 손상을 방지하기 위하여 지진상대변위가 발생할 수 있는 위치에 지진분리이음 또는 지진분리장치의 적용이 요구된다. 신축관이음 중 하나인 벨로우즈는 지진분리이음으로 적용 할 수 있다. 본 논문에서는 3ply 금속 벨로우즈 신축관이음의 온도차에 의한 내진성능의 변화를 분석하기 위한 실험적 연구를 수행하였다. 상온환경에서 점진증폭 반복하중재하실험을 수행하였으며, -20°C의 저온조건에서 동일한 실험을 수행하고 그 결과 를 비교하였다. 실험 결과로부터, -20°C의 저온환경에서 금속벨로우즈의 변위성능은 약 10% 저하될 수 있음을 확인하였다.

흰점박이꽃무지(Protaetia brevitarsis seulensis) 유충을 사육상자(가로 543 × 세로 363 × 높이 188 mm) 안에서 뽕나무 발효톱밥 기반 사료 를 이용하여 집단으로 사육할 때(25°C, 16:8 L:D), 투입될 수 있는 갓 부화한 유충의 밀도를 검토하였다. 100-175마리 투입구는 90일후 생존율 이 80% 이상으로 사육밀도 사이에 차이가 없었다. 그러나 200마리 밀도에서는 생존율이 약 10% 이상 감소하였다. 100-150마리 밀도에서 유충 평균 무게는 처리 밀도 사이에 유의한 차이가 없었으나, 175마리와 200마리 밀도에서는 100마리 밀도에 비해 유충 무게가 유의하게 낮았다. 사 육밀도가 낮을수록 유충 무게가 더 빨리 증가하였다. 이상의 결과를 종합하여 100-150마리가 처음 투입밀도로 적절하다고 판단하였다. 두 번째 실험으로, 종령 유충을 저온에 보관하는 조건을 검토하였다. 종령 유충을 4개의 무게 집단(1.8-2.0, 2.0-2.3, 2.3-2.5, 2.5 g 이상)으로 구분하여 4, 8, 10°C에 보관하였을 때, 4°C에서는 70일 보관된 유충들은 무게에 관계없이 모두 사망하였다. 그러나 8°C에서는 70일 보관집단에서 약 80%의 유충이 생존하였다. 보관하는 유충의 무게가 무거울수록 생존율이 높았다. 4°C 보관에서는 무게가 2.3 g 이상인 유충을 50일까지 보관한 후 우화 한 성충들만 적은 수의 산란을 하였다. 8°C와 10°C 처리에서는 유충 무게에 관계 없이 모두 산란을 하였다. 이상의 결과로부터 무게가 2.3 g 이상 인 흰점박이꽃무지 종령 유충을 8°C에서 30-50일 범위에서 저장할 수 있다고 판단하였다.

In the present study, the experimental study was conducted using a multi-calorie meter, to investigate the cooling performance and cycle operation changes of the multi-heat pump (3 indoor units) for the low outside temperature in summer. The test temperature condition was the low cooling temperature, and the normal performance and dynamic behavior of 3 rooms, 2 rooms, and 1 room were measured to understand the operating characteristics of seven 7 indoor unit combinations. As a result of the experiment, the cooling capacity and COP of the multi-heat pump at low cooling temperature were about 10% and 6% higher than those of the cooling standard temperature. In addition, the dynamic behavior of the indoor units of 3 and 2 rooms was observed differently due to the load difference according to the indoor unit combinations and the non-uniformity of the refrigerant amount. And, when starting the heat pump, the compressor had a maximum peak value and stabilized by repeating the decrease and increase for each indoor unit combination.

In a nuclear power plant, the activated corrosion products are deposited on the reactor coolant system. The activated corrosion products must be removed to reduce the radiation exposure to workers before maintaining or decommissioning of the nuclear power plant. In order to remove the remove the activated duplex oxide layer generated on the reactor coolant system in the pressurized water reactor (PWR), the Cyclic SP (Sulfuric acid/Permanganate)-HyBRID (Hydrazine Based Reductive metal Ion Decontamination) process developed by KAERI (Korea Atomic Energy Research Institute) can be used. After applying the Cyclic SP-HyBRID process, a sulfate-rich waste powder containing the radionuclide is generated, and the radioactive powder has to be stabilized for final disposal. In the previous study, it was confirmed that the low-temperature sintering method can be applied to immobilize the sulfate-rich waste powder. Thus, immobilization of the Cyclic SP-HyBRID process waste powder was carried out by the low-temperature sintering method using a low melting point glass, and the physicochemical and radiological characteristics of a waste form were evaluated in this study. As a result, the compressive strength of the waste form increased with increasing sintering temperature and sintering time. It is considered that the result was caused by the difference in the band gap between the bismuth borate and zinc borate, which are the products during the sintering process. It was verified that the physical stability was maintained after the 107 Gy of irradiation test. In addition, it was confirmed that the radioactive metal hydroxides contained in the waste powder converted to metal oxide forms, which have the lower solubility, at the sintering temperature. Finally, the waste form was evaluated as a low-level radioactive waste from the concentration of radionuclides contained in the waste form.

In this paper, cycle performance analysis of two-stage compression two-stage expansion refrigeration system using eco-friendly refrigerants is presented to offer the basic design data for the operating parameters of the system. Eco-friendly refrigerant R600a(Isobutane) for freon refrigerant R22 were used working fluids in this study. The coefficient of performance(COP) of R600a is about 5% greater than that of R22 two-stage compression refrigeration system in the range of evaporation temperature –30℃∼-60℃. The coefficient of performance of two-stage compression and two-stage expansion refrigeration system decreases with the increasing condensation temperature and superheating degree but increases with the increasing evaporation temperature, subcooling degree and mass flow rate ration of intercooler.

글루탐산은 식물의 생장과 발달에 중요한 역할을 하는 필수 아미노산의 전구체이며, 저온 보호 물질로 이어지는 생합성 경로를 자극하여 저온 피해를 줄이는 생물자극제 중 하나이 다. 본 연구에서는 저온 스트레스 조건에서 글루탐산 엽면 처 리가 배추에 미치는 영향을 평가하였다. 글루탐산 2가지 엽면 시비 농도(0 및 10mg·L-1)와 3가지 주/야간 온도 수준(11/－1 °C extremely low, E; 16/4°C moderately low, M; 21/9°C optimal, O)을 결합하여 6개의 처리가 수행되었다. 글루탐산 의 엽면 처리는 정식 후 10일에 1회 살포하고, 글루탐산 처리 직후 온도 처리는 최대 4일 동안 실시하였다. 처리 4일 후, ABA, PA, DPA 및 ABA-GE 함량은 M 처리에서 Glu 0 처리 보다 Glu 10 처리에서 함량이 더 높았다. Glucose 함량은 E 및 Glu 10 처리에서 가장 높은 반면(52.1mg·100g-1 dry weight), fructose 함량은 O 및 Glu 0 처리에서 함량이 가장 높았다 (134.6mg·100g-1 dry weight). GLP, GBS, 4MGBS, GNBS 및 GNS 함량은 E 및 Glu 10 처리에서 모든 처리 중 가장 높았 다(0.72, 2.05, 1.67, 9.40 및 0.85μmol·g-1 dry weight). 처리 2일 후 E 및 Glu 10 처리의 PA와 DPA함량에서 급격한 변화 를 확인하였고, 몇몇 개별 glucosinolate 함량(GLP, GBS, 4MGBS, GNBS 및 GNS)은 저온과 글루탐산 처리에 따라 유 의적 차이를 확인할 수 있었다. 또한, fructose는 glucose 대신 fructan을 에너지원으로 사용하였기 때문에 처리 4일후 E와 M처리에서 O 처리에 비하여 유의적으로 낮은 함량을 보였다. 따라서, 저온과 글루탐산 엽면 처리에 따른 PA, DPA, glucose, fructose 및 개별 glucosinolate 물질들의 변이를 확 인하였지만, 저온과 글루탐산의 효과에 관한 명확한 상관관계를 평가할 수는 없었다. 배추과 작물은 호냉성 채소로서 저 온에 민감하게 반응하지 않고, 대부분 내한성을 가지고 있기 때문으로 판단된다.

Measurement of the physical properties of high-temperature molten salts is important for the efficient design and operation of molten salt reactors (MSR) in which the reactor coolant and nuclear fuel are in a homogeneous liquid state. Although some crucial physical properties such as viscosity, thermal conductivity, density, etc., have been drawing much attention, relative data, especially for molten chloride salts, are scarce. Thus, it is urgent to prepare the viscosity data as one of the key transport properties in thermal hydraulics analysis. However, it is not an easy task to measure the molten salt viscosity with high accuracy due to end effect, a small gap between the chamber and spindle, thermal expansion of the chamber and spindle at high temperatures in a rotational viscometer. Additionally, molten salt temperatures inside furnace are not uniform due to the large temperature gradient inside the chamber, and therefore the assumption of laminar condition can be violated. In this study, geometric factors, which can be a major interference in the torque measurement, were considered for the accurate determination of the viscosity. We established a high-temperature molten salt viscosity measurement system with Brookfield rotational viscometer. KNO3 molten salt was used as a model substance at a temperature range of 650–773 K. In-house designed spindles and chambers were made of corrosion-resistant alumina. Thermal expansion has a significant influence on the size and shape of the chamber and spindle. The effect of thermal expansion on the conventional correction method was examined with temperature variation and distribution. Gap size variation was also investigated in order to improve the accuracy.