• International Journal of Aerospace System Engineering
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• 제2권2호
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• pp.29-33
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• 2015

The multidisciplinary design optimization (MDO) of a launch vehicle (LV) with a hybrid rocket engine (HRE) was carried out to investigate the ability of an HRE for a single-stage LV. The non-dominated sorting genetic algorithm-II (NSGA-II) was employed to solve two design problems. The design problems were formulated as two-objective cases involving maximization of the downrange distance over the target flight altitude and minimization of the gross weight, for two target altitudes: 50.0 km and 100.0 km. Each objective function was empirically estimated. Several non-dominated solutions were obtained using the NSGA-II for each design problem, and in each case, a trade-off was observed between the two objective functions. The results for the two design problem indicate that economical performance of the LV is limited with the HRE in terms of the maximum downrange distances achievable. The LV geometries determined from the non-dominated solutions were examined.

• 한국분무공학회지
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• 제24권1호
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• pp.21-26
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• 2019

In Korea, Medium-duty trucks are classified into GVW (Gross Vehicle Weight) 3.5~10tons. MDTs are mostly used for logistics or delivery between regions. There have been studied on diesel fuel vehicles for SUVs(Sports Utility Vehicle) or light-duty trucks. But MDTs have been not studied. Therefore, this study have been used MDTs for characteristic exhaust emission. Test was carried out using the certification test mode (NEDC, New European Driving cycle) and the NIER mode in chassis dynamometer of the MDTs. And emission gas was analyzed for PN (Particulate Number), PN size distribution and aldehydes, VOCs (Volatile Organic Compounds), PAHs (Polycyclic Aromatic Hydrocarbons). This paper concluded that EURO-IV trucks produced more MSATs than EURO V trucks. Depending on the engine temperature, more MSATs were generated in cold temperature than in the hot start operation. However, the driving speed, the opposite results was obtained.

• Computers and Concrete
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• 제32권4호
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• pp.411-423
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• 2023

The rapid development of road transport has increased the number of bridges that require widening. A critical issue in the construction of bridge widening is the influence of vibrations of the old bridge on the casting of wet joint concrete between the old and new bridges owing to the running traffic. Typically, the bridge is closed to traffic during the pouring of wet joint concrete, which negatively affects the existing transportation network. In this study, a newly developed microscopic traffic load modeling approach and the vehicle-bridge interaction theory are incorporated to develop a refined numerical framework for the analysis of random traffic-bridge coupled dynamics. This framework was used to investigate traffic-induced vibrations at the wet joint of a widened bridge. Based on an experimental study on the vibration resistance of wet joint concrete, traffic control strategies were proposed to ensure the construction performance of cast-in-site wet joint concrete under random traffic without interruption. The results show that the vibration displacement and frequency of the old bridge, estimated by the proposed framework, were comparable with those obtained from field measurements. Based on the target peak particle velocity and vibration amplitude of the wet joint concrete, it was found that traffic control measures, such as limiting vehicle gross weight and limiting traffic volume by closing an additional traffic lane, could ensure the construction performance of the wet joint concrete.

• 한국기계연구소 소보
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• 통권13호
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• pp.3-13
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• 1984

Fatigue failure of axle housing could cause many injuries and much financial loss. This challenges the engineer to improve design decisions involving fatigue. Endurance evaluation of axle housing is great interest to auto-mobile manufacturers for the sake of safety and reliability. Axle housing is subjected to gross vehicle weight(G.V.W)as mean load and alternating load. Theoretical design diagram involving mean and alternating stresses is used for the evaluation of axle housing fatigue endurance with the equivalent stress of fatigue critical area on the axle housing. Four point bending fatigue tests on axle housing with constant amplitude loading at approximately R=0 were performed with 50 ton servohydraulic strucural fatigue testing machine developed at KIMM. Specimens were made with the same material STKM 13B as the axle housing and tested to obtain S_N data. Five specimens of STKM 13B were tested at 253.61 MPa and weibull distribution was obtained at the same stress level. Material data and structural data were compares and fatigue stress property factor and fatigue life property factor were obtained.

• 한국독성학회:학술대회논문집
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• 한국독성학회 2003년도 추계학술대회
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• pp.132-132
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• 2003

In this GLP study, 4 study groups of 12 Sprague-Dawley (SD) rats/sex were given vehicle, or 1,000, 1,500, or 2,000 mg/kg/day Sophora Japonica Linne Seed Extract (SE) for 13 weeks. Standard endpoints in this study included mortality, clinical observations, body weight, food and water consumption, ophthalmoscopic examination, urinalysis, hematology, serum biochemistry, organ weights, gross anatomic pathology and histopathology.(omitted)

• 대한한의학방제학회지
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• 제10권2호
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• pp.73-83
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• 2002

The single dose toxicity of Jengjengamiyjintang, a herbal drug for duodenal ulcer was evaluated in male and female Sprague-Dawley (SD) rats. Jengjengamiyjintang was once administered to both sexes of rats at the dose levels of 2000, 1000, 500, 250 and 125mg／kg for oral route according to KFDA guidelines for single dose toxicity test (1999-61). In addition, vehicle control group was added in order to compare clinical signs, body weight changes and abnormal necropsy findings. After single administration, clinical signs were observed every twice a day for 14 days and body weights were measured 5 times including initial measurement on day 0. When observation period was over, the animals were sacrificed and macroscopic examination of major organs was conducted. Neither significant clinical signs nor death after administration was observed during the observation periods except for soft feces or diarrhea that were restricted to Day 1 of 2000 and 1000mg/kg-dosing groups. Although some accidental findings such as gross and histopathological changes of lung that were demonstrated in some animals of all experimental groups including vehicle control group, no abnormal necropsy findings and changes of body weight were observed at terminal necropsy in both sexes. From these results, it is considered that $LD_{50}$ of Jengjengamiyjintang is over 2000mg／kg in oral administration in both sexes of rats and approximated lethal dose was considered over 2000mg/kg.

• 대한한방내과학회지
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• 제35권1호
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• pp.37-49
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• 2014

목적 및 방법 : 본 연구에서는 한의학에서 전통적으로 신경보호 약물로 사용되어온 총명탕 물 추출물의 급성 독성증상을 관찰하기 위하여 한국식품의약품안전청 고시 제 2009-116호에 따라 암수 ICR마우스 단회 경구투여 독성 실험을 실시하였다. 반수치사량, 개략적치사량, 표적장기 등을 관찰하기 위하여, 수율 9.70% 총명탕 물 추출물 2,000, 1,000 및 500 mg/kg을 암수 마우스에 단회 경구 투여하고, 투여 후 14일 동안의 임상증상, 사망례, 체중 및 증체량의 변화 및 부검소견을 관찰하였으며, 투여 14일 후 14개 주요 실질 장기에 대한 중량 및 조직병리학적 관찰을 실시하였다. 또한 별도의 암수 매체 대조군을 두어 그 결과를 비교하였다. 결 과 : 본 실험의 결과, 설치류 최대 한계투여 용량인 2,000 mg/kg까지 총명탕 물 추출물 투여와 관련된 사망례가 인정되지 않았으며, 암수 매체 대조군을 포함하여, 모든 실험군에 걸쳐 산발적으로 관찰된 일부 우발적인 육안부검 및 조직병리학적 소견을 제외하고, 총명탕 물 추출물 투여와 관련된 임상증상, 체중 및 장기 중량의 변화, 14개 주요장기에 대한 육안부검 및 조직병리학적 소견이 인정되지 않았다. 결 론 : 따라서 마우스 단회 경구투여 독성실험에서 총명탕 물 추출물의 반수치사량 및 개략적 치사량은 각각 설치류 투여 한계용량인 2,000 mg/kg 이상으로 관찰되어, 매우 안전한 약물로 판단되며, 임상사용에는 별 다른 문제를 일으키지는 않을 것으로 판단된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1246-1247
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• 2008

With recent advanced in portable electric devices, wireless sensor, MEMS and bio-Mechanics device, the new typed power supply, not conventional battery but self-powered energy source is needed. Particularly, the system that harvests from their environments are interests for use in self powered devices. For very low powered devices, environmental energy may be enough to use power source. Therefore, in other to made piezoelectric energy harvesting device, PMN-PZT thick film was formed by the screen printing method on the Ag/Pd coated alumina substrate. The layer was 8 layers and slurry where a-terpineol, ethycellulose, ferro B-75001 as Vehicle, PMN-PZT powder used are fabricated by ball mill. The output power quality was be also investigated by changing the load resistance, weight and frequency. The made piezoelectric energy harvesting device was resulted from the conditions of 33$k{\Omega}$, 0.25g, 197Hz respectively. The thick film was prepared at the condition of 2.75Vrms, and its power was 230${\mu} W$ and its thickness was 56${mu}m$. The piezoelectric energy harvesting device output voltage was increased, when the load weight, load resistance was increasing and resonance frequency was diminishing. The other side, resonance frequency was diminished, when the weight was increasing. And output power was continuously it changed by load resistance, output voltage, weight and resonance frequency.

• International Journal of Industrial Entomology and Biomaterials
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• 제32권1호
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• pp.12-25
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• 2016

Recently, research investment in the improvement of food safety as a food source and specializing of nutritional source of edible insects is being actively conducted. Cricket especially has been attracting considerable interest in entomophagy; however, research on the safety assessment of cricket is limited. This study investigated the effects of cricket ethanol extract when orally administrated in Sprague-Dawley rats. Here, we performed a 4 wk repeated oral dose toxicity test in Sprague-Dawley rats following the Organization for Economic Cooperation and Development test guidelines 407 under Good Laboratory Practice regulation. Rats were randomly allocated 4 groups: vehicle control, 250, 500, 1,000 mg/kg test groups and administrated based on body weight for 28 d. The animals were observed for mortalities and clinical signs, body weight changes, food and water consumption. At the end of treatment period, blood and urine were collected and analyzed. Subsequently, the animals were sacrificed and subjected to gross pathological examination and organ weight measurement. The organs were preserved for histopathological examination. The results showed that there were no systemic toxicological effects related with the cricket ethanol extract in the 4 wk oral repeated dose toxicity study. It is considered that NOAEL of cricket ethanol extract is greater than 1,000 mg/kg/d and there was no target organ detected.

• 대한본초학회지
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• 제34권3호
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• pp.31-36
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• 2019

Objectives : In this animal study, we performed the single oral dose toxicity test of Standardized Cornus officinalis Sieb. et Zucc. and Psoralea corylifolia L. 30% ethanol extract (SCP) in Sprague-Dawley (SD) rats owing to aims for verifying approximate lethal dose (ALD). Methods : According to OECD guidelines for the testing of chemicals section 4 health effects test No. 420 acute oral toxicity study - fixed dose procedure (17 December 2001), single oral dose toxicity test was performed. Animals were divided into two groups: Group 1, vehicle-treated rats (Control); Group 2, SCP 5000 mg/kg treated rats. SCP is composed of two medicinal herbs: Cornus officinalis Sieb. et Zucc. (650 g) and Psoralea corylifolia L. (350 g) in 30% ethanol. SCP was once orally administered to female and male SD rats at dose levels of 5000 mg/kg. Animals were monitored on the mortality, clinical signs, body weight changes and necropsy findings for 14 days. Results : After single oral treatment of SCP, we could not find any mortality up to 5000 mg/kg. Compared with the control group, there were also no significant differences in clinical sign, weight change, weight gain and gross abnormalities in SCP 5000 mg/kg-treated group. Conclusions : Taken together, these results suggest that the ALD of SCP in both female and male SD rats were considered as over 5000 mg/kg. Results from this study provide scientific evidence for the safety of SCP.