플라즈마 용사에 의한 BSCCO 초전도체 형성을 위한 용사 분말의 제조에 관한 연구

박정식,조창은,박경채,Park, Jeong-Sik,Cho, Chang-Eun,Park, Kyung-Chae 한국분말야금학회 2008 한국분말재료학회지 (KPMI) Vol.15 No.6

Formation and characteristics of spraying powder for BSCCO High-Tc superconductor prepared by plasma spray coating were investigated. The addition of 3% of binder gives the best flowability of the powder. Ball milling for 30h and 35h gives the best flowability of powder in the case of 2001 and 0212, respectively. The withdraw ratio increases upon binder addition from 12 to 27% in the case of 2001 and from 18 to 31% in the case of 0212 for sieving powder of $30-90{\mu}m$ in size. The built-up efficiency for $100{\mu}m$ thickness of spray coating is increased more than 30% by binder addition. The microstructure of the spray coated layers was investigated by XRD and EDS analysis.

BSCCO 플라즈마 용사피막의 부분용융열처리 후 어닐링 시간에 따른 초전도 특성

박정식,이선홍,박경채,Park, Jeong-Sik,Lee, Seon-Hong,Park, Kyeung-Chae 한국재료학회 2014 한국재료학회지 Vol.24 No.2

$Bi_2Sr_2CaCu_2O_x$(Bi-2212) and $Bi_2Sr_2Ca_2Cu_3O_y$(Bi-2223) high-Tc superconductors(HTS) have been manufactured by plasma spraying, partial melt process(PMP) and annealing treatment(AT). A Bi-2212/2223 HTS coating layer was synthesized through the peritectic reaction between a 0212 oxide coating layer and 2001 oxide coating layer by the PMP-AT process. The 2212 HTS layer consists of whiskers grown in the diffusion direction. The Bi-2223 phase and secondary phase in the Bi-2212 layer were observed. The secondary phase was distributed uniformly over the whole layer. As annealing time goes on, the Bi-2212 phase decreases with mis-orientation and irregular shape, but the Bi-2223 phase increases because a new Bi-2223 phase is formed inside the pre-existing Bi-2212 crystals, and because of the nucleation of a Bi-2223 phase at the edge of Bi-2212 crystals by diffusion of Ca and Cu-O bilayers. In this study the spray coated layer showed superconducting transitions with an onset Tc of about both 115 K, and 50 K. There were two steps. Step 1 at 115 K is due to the diamagnetism of the Bi-2223 phase and step 2 at 50 K is due to the diamagnetism of the Bi-2212 phase.

3GPP 운영위원회(PCG) 및 표준화단체(OP) 회의

박정식,류창호,Park, Jeong-Sik,Ryu, Chang-Ho 한국정보통신기술협회 2006 TTA저널 Vol.105 No.-

OMA 일본 오사카 회의

박정식,Park, Jeong-Sik 한국정보통신기술협회 2006 TTA저널 Vol.106 No.-

3GPP2 일본 미야자끼 회의

박정식,Park, Jeong-Sik 한국정보통신기술협회 2006 TTA저널 Vol.106 No.-

적응 콤 필터링을 이용한 이동 통신 환경에서의 강인한 음성 인식

박정식,정규준,오영환,Park Jeong-Sik,Jung Gue-Jun,Oh Yung-Hwan 대한음성학회 2003 말소리 Vol.46 No.-

In this paper, we employ the adaptive comb filtering for effective noise reduction in mobile communication environment. Adaptive comb filtering is a well-known method for noise reduction, but requires correct pitch period and must be applied just in voiced speech frames. To satisfy these requirements we use two kinds of information extracted from speech packets, one of which is the pitch period information measured precisely by a speech coder and the other is the frame rate information related to a decision on speech or silence frame. Experiments on speech recognition system confirm the efficiency of this method. Feature parameters employing this method give superior performance in noise environment to those extracted directly from output speech.

OFDMA 시스템에서 실시간 트래픽 전송을 위한 효율적 스케쥴링 기법

박정식,조호신,Park, Jeong-Sik,Cho, Ho-Shin 한국통신학회 2007 韓國通信學會論文誌 Vol.32 No.1A

본 논문에서는 OFDMA(Orthogonal Frequency Division Multiple Access) 시스템에서 실시간 트래픽 전송을 위한 효율적 패킷 스케줄링 기법을 제안한다. 본 방식은 패킷의 시간 지연 구속을 우선 만족시키면서 데이터 전송률도 향상시키는 기법으로 TEDC(Throughput Enhancement Under Delay-Constraint)라 불리운다. 사용자별 트래픽 특성에 따른 허용 지연 시간(Tolerable Delay Time TDT)을 정의하여 다양한 시간 지연 요구 조건을 차별화 하여 관리함으로써 무선 자원의 사용 효율을 향상시킨다. 논문에서 제안하는 TEDC 방식은 두 단계로 이루어진다. 첫 번째 단계에서는, 실시간 서비스를 위해 요구되는 시간 지연 구속을 만족하기 위해 잔여 허용 시간이 남지 않은 긴급한 사용자들에게 우선적으로 무선자원을 할당한다. 두 번째 단계에서는 첫 번째 단계에서 할당하고 남은 잉여 무선 자원에 대해서 자원의 활용도를 최대화하여 전체 데이터 전송률(Throughput)을 향상시킨다. 제안된 TEDC 방식의 성능은 기존의 자원할당 방식인 Round robin, M-LWDF, EXP 방식과 패킷 손실률, 데이터 전송률, 채널 활용도 측면에서 비교, 분석된다. 시뮬레이션 결과, TEDC 방식이 패킷 손실률, 데이터 전송률, 채널 활용도 측면에서 다른 자원 할당 방식보다 모두 우수한 성능을 보였다. In this paper, a packet scheduling scheme that supports real-time traffic having multi-level delay constraints in OFDMA systems is proposed. The proposed scheme pursues to satisfy the delay constraint first, and then manage the residual radio resource in order to enhance the overall throughput. A parameters named tolerable delay time (TDT) is newly defined to deal with the differentiated behaviors of packet scheduling according to the delay constraint level. Assuming that the packets violating the delay constraint are discarded, the proposed scheme is evaluated in terms of the packet loss probability, throughput, channel utilization. It is then compared with existing schemes for real-time traffic support such as the Exponential Scheduling (EXP) scheme, the Modified Largest Weighted Delay First (M-LWDF) scheme, and the Round robin scheme. The numerical results show that the proposed scheduling scheme performs much better than the aforementioned scheduling schemes in terms of the packet loss probability, while slightly better in terms of throughput and channel utilization.

느타리버섯의 저장조건(貯藏條件)이 자실체(子實體)의 화학성분(化學成分)에 미치는 영향(影響)

박정식,김성열,Park, Jeong Sik,Kim, Seong Yeol 충남대학교 농업과학연구소 1986 Korean Journal of Agricultural Science Vol.13 No.1

These studies were conducted to elucidate the effect of storage conditions on the changes of chemical components in fruit bodies of oyster mushroom(Pleurotus ostreatus), and the results obtained were as follows. 1. The fruit bodies of oyster mushroom sealed with polyethlene film 0.03 mm thickness maintained their freshness for 15 days at $1^{\circ}C$, 10 days at $5^{\circ}C$ and 3 days at $20^{\circ}C$. 2. The respiration rates of the fruit bodies grown in the rice-straw substrate was 29.7mg $CO_2/kg$ F.W/hr. at $1^{\circ}C$, 32.7mg at $5^{\circ}C$, and 46.3mg at $20^{\circ}C$ during the storage, respectively. The respiration rate showed the highest level at the second day during the storage. 3. The contents of total and reducing sugar during the storage of oyster mushroom rapidly increased at $5^{\circ}C$ until the fifth day following slowly decreased. 4. The content of protein in the oyster mushroom was reduced during the storage, while the free amino acid slightly increased. 5. The change of RNA and DNA contents during the storage of oyster mushroom showed inconsistency on the temperature and the storage period. 본(本) 연구(硏究) 저장조건(貯藏條件)에 따른 자실체(子實體)의 화학성분(化學成分) 변화(變化)를 조사(調査)하여 합리적(合理的)인 생체저장방법(生體財藏方法)을 구명(究明)하기 위(爲)한 기초자료(基礎資料)를 얻고자 실시(實施)한 결과(結果)는 다음과 같다. 1. 느타리버섯을 0.03mm 두께의 polyethylene film으로 밀봉포장(密封包裝)하였을 때 $1^{\circ}C$에서는 15일(日), $5^{\circ}C$에서는 10일(日), $20^{\circ}C$에서는 3일간(日閒) 선도(鮮度)가 유지(維持) 되었다. 2. 저장온도(貯藏溫度)에 따르는 느타리버섯 자실체(子實體)의 호흡량(呼吸量)은 $1^{\circ}C$에서 $29.7mgCO_2/kg/hr$, $5^{\circ}C$에서는 $32.7mgCO_2/kg/hr$, $20^{\circ}C$에서는 $46.3mgCO_2/kg/hr$ 로 온도(溫度)가 상승(上昇)함에 따라 증가(增加)하였으며 저장(貯藏), 후(後) 2일(日)째에 가장 높았다. 3. 총당(總糖)과 환원당(還元糖)의 함량(含量)은 저장초기(貯藏初期)에 급격(急激)히 증가(增加)하여 5일(日)째에 최고(最高)에 달(達)하였고 그 후(後)에는 점차(漸次) 감소(減少)하였다. 4. 저장기간(貯藏期間)이 길수록 자실체중(子實體中)의 alkali 가용성단백질(可溶性蛋白質)의 함량(含量)은 감소(減少)하고 유리(遊離) amino 산(酸)의 함량(含量)은 증가(增加) 경향(傾向)을 나타내었다. 5. 저장온도(貯藏溫度) 및 기간(期間)에 따르는 DNA 및 RNA 함량(含量)의 변화(變化)는 일정(一定)한 경향(傾向)을 나타내지 않았다.

MMSE Estimator 기반의 적응 콤 필터링을 이용한 잡음 제거

박정식,오영환,Park, Jeong-Sik,Oh, Yung-Hwan 대한음성학회 2006 말소리 Vol.60 No.-

This paper describes a speech enhancement scheme that leads to significant improvements in recognition performance when used in the ASR front-end. The proposed approach is based on adaptive comb filtering and an MMSE-related parameter estimator. While adaptive comb filtering reduces noise components remarkably, it is rarely effective in reducing non-stationary noises. Furthermore, due to the uniformly distributed frequency response of the comb-filter, it can cause serious distortion to clean speech signals. This paper proposes an improved comb-filter that adjusts its spectral magnitude to the original speech, based on the speech absence probability and the gain modification function. In addition, we introduce the modified comb filtering-based speech enhancement scheme for ASR in mobile environments. Evaluation experiments carried out using the Aurora 2 database demonstrate that the proposed method outperforms conventional adaptive comb filtering techniques in both clean and noisy environments.

알코올 및 바이러스성 간경변증에서 세균성 감염 빈도의 비교

박정식(Jeong Sik Park),조용균(Yong Kyun Cho),이은정(Eun Jung Rhee),정수석(Soo Suk Jeong),김시영(Si Young Kim),김창섭(Chang Seop Kim),박창영(Chang Young Park),손정일(Chung Il Sohn),전우규(Woo Kyu Jeon),김병익(Byung Ik Kim),정을순(Eul 대한내과학회 2002 대한내과학회지 Vol.62 No.2

N/A Background: Liver cirrhosis may be considered one of the most common cause of acquired immunodeficiency. Alcohol abuse may be predisposing factor to infections in patients with liver cirrhosis, so we compared the rate of spontaneous bacterial peritonitis (SBP) and other bacterial infections in alcoholic and viral liver cirrhosis. Methods: We studied 188 patients who had been diagnosed with liver cirrhosis from January 1995 to June 2000 and evaluated the frequency of bacterial infections (SBP, pneumonia, urinary track infection, bacteremia, infectious colitis) retrospectively according to cause and degree of cirrhosis. Results: Among 188 patients (alcoholic 76, viral 112), 64 patients (34%) presented with bacterial infection at hospitalization, 33 (43%;33/76) of 64 subjects were alcoholic and 31 (28%;31/112) of 64 subjects were viral liver cirrhosis. The rate of bacterial infections was higher in alcoholic liver cirrhosis than viral cirrhosis (p<0.05). The rate of SBP and other bacterial infections were more frequent in patients of Child-Pugh class C than in those of Child-Pugh class A and B (p<0.01, p<0.05) respectively. Patients of alcoholic liver cirrhosis were more susceptible to bacterial infection than those of viral liver cirrhosis with Child-Pugh class A/B (p<0.05), but no difference was noted in patients of Child-Pugh class C (p>0.05). Conclusion: This results suggest that the rate of bacterial infections are more common in alcoholic than viral liver cirrhosis in relatively early stage and it may be influence the prognosis of liver cirrhosis.(Korean J Med 62:159-164, 2002)