AZ91 합금융체내의 Fe 용해도

권순일,변지영,김선진,심재동 대한금속재료학회 2004 대한금속·재료학회지 Vol.42 No.1

Fe solubility in AZ91 alloy melts was measured by a new method designed for removal of Al_(8)(Mn,Fe)_(5) inclusions. In the AZ91 alloy melts, Al_(8)(Mn,Fe)_(5) precipitates were formed due to supersaturated Mn and Fe, but all precipitates were not settled down from the melts and hence part of them was included in the samples for measuring Fe solubility. This means that the solubility measured from these samples is higher than the true solubility. In the present study, it was shown that these Al_(8)(Mn,Fe)_(5) inclusions could be separated from the samples by the new method. As a result, the Fe solubility measured by the present method was lower than the previous solubility data. Amount of the unsettled Al_(8)(Mn,Fe)_(5) inclusions was estimated to be 59-148 ppm. It was also observed that Fe contents in Al_(8)(Mn,Fe)_(5) were varied with the Fe and Mn content in AZ91 alloy melts.

모 주물공장 근로자의 작업공정별 분진폭로량, 자각증상 및 건강진단판정 비교

이범식,조영채,변정식,김동현,원선혜,김정윤 忠南大學校 環境問題硏究所 1995 環境硏究 Vol.13 No.-

The relationship among dust exposure dose, special health diagnosis results and subjective symptom questionaire survey for 109 casting foundry workers supervised by a local laber office has been studied from august to october 1993. Subjective symptom, dust exposure dose and health examination evaluation of respective working processes have been analized and concluded as follows; 1. Metal fume concentration in melting process measured 3.21±1.46㎎/㎥ is under threshould limit value(TLV;5.0㎎/㎥), casting sand dust measured in molding and desanding process is 5.8 ±3.41㎎/㎥ and 9.69 ±2.64㎎/㎥ which is 3-5 times higher than TLV(2.0㎎/㎥), metal fume, welding fume and metal dust in finishing process measured 9.34 ±1.32, 13.73 ±16.97 and 10.17 ±3.50㎎/㎥ respectively, which are also 2-3 times higher than TLV(5.0㎎/㎥). 2. The complain rate subjective symptoms appeal evaluated for finishing process are 35.9%, 46.2%, 27.2% and 42.2% for eye smptoms, respiractory, skin, general symptom respectively and the rates above express the highest values and the complain rates for melting process are 24.4%, 37.5% and 35.7% for eye smptoms, respiratory and mental system respectively and for molding and desanding it is 24.3%. 3. Perceived occupational disease rate is found 0.9% with are out of 109 worker surveyed who have been exposed in metal fume of finishing process. 4. 33.0% of workers surved are found to require close examination, the worker of hepatopathy suspected are 21.4% which is the highest and 3.7% for circulatory disturbance suspected. 5. The statistically significant variables in general chracteristics that affect health examination evaluation are smoking(P<0.001), respirator put-on (P<0.05) and working career(P<0.05). 6. Cough(P<0.001), "headache"(P<0.05) and "easily skin exchange by slight stimulation" (P<0.05) are statistically significant to the subjective symptom variables affect health examination evaluation.

Bark Constituents from Mushroom-detoxified $Rhus$ $verniciflua$ Suppress Kainic Acid-induced Neuronal Cell Death in Mouse Hippocampus

Byun, Jong-Seon,Han, Yoon-Hee,Hong, Sung-Jun,Hwang, Sung-Mi,Kwon, Yong-Soo,Lee, Hee-Jae,Kim, Sung-Soo,Kim, Myong-Jo,Chun, Wan-Joo The Korean Society of Pharmacology 2010 The Korean Journal of Physiology & Pharmacology Vol.14 No.5

Urushinol, a plant allergen, has significantly restricted the medical application of $Rhus$ $verniciflua$, although it has been reported to possess a wide variety of biological activities such as anti-inflammatory, antioxidant, and anti-cancer actions. To reduce the urushinol content while maintaining the beneficial biological activities, mushroom-mediated fermentation of $Rhus$ $verniciflua$ was carried out and this method resulted in significantly attenuated allergenicity [1]. In the present study, to examine the neuroprotective properties of mushroom-fermented stem bark of $Rhus$ $verniciflua$, two constituents were isolated from mushroom-fermented bark and their neuroprotective properties were examined in a mouse model of kainic acid (KA)-induced excitotoxicity. KA resulted in significant apoptotic neuronal cell death in the CA3 region of mouse hippocampus. However, seven daily administrations of RVH-1 or RVH-2 prior to KA injection significantly attenuated KA-induced pyramidal neuronal cell death in the CA3 region. Furthermore, pretreatment with RVH-1 and RVH-2 also suppressed KA-induced microglial activation in the mouse hippocampus. The present study demonstrates that RVH-1 and RVH-2 isolated from $Rhus$ $verniciflua$ and detoxified using mushroom species possess neuroprotective properties against KA-induced excitotoxicity. This leads to the possibility that detoxified $Rhus$ $verniciflua$ can be a valuable asset in herbal medicine.

Initial biocompatibility and enhanced osteoblast response of Si doping in a porous BCP bone graft substitute

Byun, In-Seon,Sarkar, Swapan Kumar,Anirban Jyoti, M.,Min, Young-Ki,Seo, Hyung-Seok,Lee, Byong-Taek,Song, Ho-Yeon Springer-Verlag 2010 Journal of materials science, Materials in medicin Vol.21 No.6

An Experimental Implementation of a Cross-Layer Approach for Improving TCP Performance over Cognitive Radio Networks

Byun, Sang-Seon Korea Information Processing Society 2016 Journal of information processing systems Vol.12 No.1

In cognitive radio networks (CRNs), the performance of the transmission control protocol (TCP) at the secondary user (SU) severely drops due to the mistrigger of congestion control. A long disruption is caused by the transmission of primary user, leading to the mistrigger. In this paper, we propose a cross-layer approach, called a CR-aware scheme that enhances TCP performance at the SU. The scheme is a sender side addition to the standard TCP (i.e., TCP-NewReno), and utilizes an explicit cross-layer signal delivered from a physical (or link) layer and the signal gives an indication of detecting the primary transmission (i.e., transmission of the primary user). We evaluated our scheme by implementing it onto a software radio platform, the Universal Software Radio Peripheral (USRP), where many parts of lower layer operations (i.e., operations in a link or physical layer) run as user processes. In our implementation, we ran our CR-aware scheme over IEEE 802.15.4. Furthermore, for the purpose of comparison, we implemented a selective ACK-based local recovery scheme that helps TCP isolate congestive loss from a random loss in a wireless section.

Kainic Acid-induced Neuronal Death is Attenuated by Aminoguanidine but Aggravated by L-NAME in Mouse Hippocampus

Byun, Jong-Seon,Lee, Sang-Hyun,Jeon, Seong-Ho,Kwon, Yong-Soo,Lee, Hee-Jae,Kim, Sung-Soo,Kim, Young-Myeong,Kim, Myong-Jo,Chun, Wan-Joo The Korean Society of Pharmacology 2009 The Korean Journal of Physiology & Pharmacology Vol.13 No.4

Nitric oxide (NO) has both neuroprotective and neurotoxic effects depending on its concentration and the experimental model. We tested the effects of NG-nitro-L-arginine methyl ester (L-NAME), a nonselective nitric oxide synthase (NOS) inhibitor, and aminoguanidine, a selective inducible NOS (iNOS) inhibitor, on kainic acid (KA)-induced seizures and hippocampal CA3 neuronal death. L-NAME (50 mg/kg, i.p.) and/or aminoguanidine (200 mg/kg, i.p.) were administered 1 h prior to the intracerebroventricular (i.c.v.) injection of KA. Pretreatment with L-NAME significantly increased KA-induced CA3 neuronal death, iNOS expression, and activation of microglia. However, pretreatment with aminoguanidine significantly suppressed both the KA-induced and L-NAME-aggravated hippocampal CA3 neuronal death with concomitant decreases in iNOS expression and microglial activation. The protective effect of aminoguanidine was maintained for up to 2 weeks. Furthermore, iNOS knockout mice ($iNOS^{-1-}$) were resistant to KA-induced neuronal death. The present study demonstrates that aminoguanidine attenuates KA-induced neuronal death, whereas L-NAME aggravates neuronal death, in the CA3 region of the hippocampus, suggesting that NOS isoforms play different roles in KA-induced excitotoxicity.

Measurement Allocation by Shapley Value in Wireless Sensor Networks

Byun, Sang-Seon The Korea Institute of Information and Commucation 2018 Journal of information and communication convergen Vol.16 No.1

In this paper, we consider measurement allocation problem in a spatially correlated sensor field. Our goal is to determine the probability of each sensor's being measured based on its contribution to the estimation reliability; it is desirable that a sensor improving the estimation reliability is measured more frequently. We consider a spatial correlation model of a sensor field reflecting transmission power limit, noise in measurement and transmission channel, and channel attenuation. Then the estimation reliability is defined distortion error between event source and its estimation at sink. Motivated by the correlation nature, we model the measurement allocation problem into a cooperative game, and then quantify each sensor's contribution using Shapley value. Against the intractability in the computation of exact Shapley value, we deploy a randomized method that enables to compute the approximate Shapley value within a reasonable time. Besides, we envisage a measurement scheduling achieving the balance between network lifetime and estimation reliability.

Detection of Internal Damage in CFRP-Laminated Plates Using Signal Extraction Method

Byun Seon-Woo,최동국,이수용,이철주,김상우 한국항공우주학회 2024 International Journal of Aeronautical and Space Sc Vol.25 No.1

Internal damage to carbon fibre-reinforced plastic (CFRP) laminated plates was detected and visualized. This internal damage was generated via low-velocity impact testing. Prior to the experiment, the impact velocity was established through finite element analysis based on LS-DYNA. The damage size, determined through this analysis and subsequent experiment, presented a maximum error of 17%. Piezoelectric sensors were used to detect and visualize the internal damage. This damage was identified using a diagnostic approach, along with a novel signal separation method. The signal separation method was employed because the distance between the plate edge and the sensor was smaller than the distance between the two sensors on the CFRP-laminated plates. The visualized damage was verified though a comparison with the low-velocity impact experimental results. Both the location and size of damage could be detected with an error of approximately 9.7% and 10%, respectively.

Clusterin/ApoJ enhances central leptin signaling through Lrp2‐mediated endocytosis

Byun, Kyunghee,Gil, So Young,Namkoong, Churl,Youn, Byung‐,Soo,Huang, Hu,Shin, Mi‐,Seon,Kang, Gil Myoung,Kim, Hyun‐,Kyong,Lee, Bonghee,Kim, Young‐,Bum,Kim, Min‐,Seon EMBO 2014 EMBO reports Vol.15 No.7

<P>Hypothalamic leptin signaling plays a central role in maintaining body weight homeostasis. Here, we show that clusterin/ApoJ, recently identified as an anorexigenic neuropeptide, is an important regulator in the hypothalamic leptin signaling pathway. Coadministration of clusterin potentiates the anorexigenic effect of leptin and boosts leptin-induced hypothalamic Stat3 activation. In cultured neurons, clusterin enhances receptor binding and subsequent endocytosis of leptin. These effects are mainly mediated through the LDL receptor-related protein-2 (Lrp2). Notably, inhibition of hypothalamic clusterin, Lrp2 or endocytosis abrogates anorexia and hypothalamic Stat3 activation caused by leptin. These findings propose a novel regulatory mechanism in central leptin signaling pathways.</P>

매니폴드 미니채널 구조의 유량분배 최적화를 통한 전기자동차 배터리 냉각 성능 향상에 관한 연구

변선웅(Seon Woong Byun),신현호(Hyun Ho Shin),조현구(Hyun Ku Cho),김용찬(Yongchan Kim) 대한설비공학회 2022 대한설비공학회 학술발표대회논문집 Vol.2022 No.6

As the performance of electric vehicle is improved, battery thermal management is attracting more attentions. In this paper, a novel manifold-mini-channel cooling plate (MMCP) is proposed for battery cooling. The cooling performance is improved owing to the jet impingement effect, and the pressure drop is significantly lowered owing to the increased hydraulic diameter. However, as the flow is concentrated on the front and rear sides of the MMCP, the center of the heat source shows relatively high temperature, and the temperature uniformity is decreased. In this study, the temperature uniformity of the MMCP is increased by optimizing the flow distribution. Specifically, the geometric conditions of slits on the jet plate are changed, which is inserted to maximize the jet impingement effect. As a result, the maximum temperature at the center is lowered by 5.4℃ than the baseline.