무선전송 채널에서 Differenctial encoding을 이용한 QAM 신호의 전송에 관한연구

김희구,윤두만,오동진,김철성 대한전자공학회 1996 전자공학회논문지-A Vol.33 No.4

As the demand for high-speed and wirelesstransmission of information is rapidly increasing, spectrally efficient digiral radio modulation and demodulation scheme is preferred. In this paper, we have studied the signal generation, demodulation and performance evaluation of spectrally efficient QAM signals in a wireless channel environment. We propose differential modulation and demodulation scheme for QAM in rayleigh fading channel. First, formulas for theerror probability of proposed QAM scheme are derived over QWGN channel. Second, we evaluate the performance of the proposed QAM scheme in rayleigh fading environment through computer simulation, and confirm that it shows much better performance compared to that of conventional QAM scheme.

일반한천, 분무건조한천, 압출성형한천의 열 특성 및 표면구조의 비교

김희구,손홍주 한국식품영양학회 1997 韓國食品營養學會誌 Vol.10 No.2

식품산업을 포함한 다양한 분야에서 이용되고 있는 한천의 용도를 개발하기 위하여 각종 물리적인 처리가 한천의 열적 특성에 미치는 영향과 각 처리에 따른 표면구조의 변화를 조사하였다. 시차주사 열량분석기를 이용하여 조사한 일반한천의 흡열개시온도(T_o), 최대흡열점의 온도(T_p) 및 흡열완료온도(T_c)는 81.02, 95.51, 및 112.14℃였으며, 분무건조한천은 60.11, 76.45 및 89.54℃였고, 압출성형한천은 41.30, 61.72 및 80.50℃로 압출성형한천이 가장 낮은 온도에서 진행되었다. 또한 엔탈피도 일반한천 3.22cal/g, 분무건조한천 1.53cal/g, 압출성형한천 0.73cal/g의 순서로 압출성형한천에서 가장 낮았다. 완전히 가열용해한 각 한천을 다시 냉각, 응고 후에 다시 승온하였을 때의 T_o ,T_p 및 T_c는 일반한천 80.70, 95.61 및 110.92℃, 분무건조한천 79.54, 93.76 및 109.84℃, 압출성형한천 79.25, 93.19 및 108.77℃로 한천의 종류에 따른 차이는 없었다. 엔탈피 역시 큰 차이를 보이지 않았다. 광학현미경과 주사 전자현미경에 의해 표면구조를 관찰한 결과, 일반한천의 경우 단단한 구조로 균열이나 기공들이 관찰되지 않았고, 분무건조한천은 많은 미세입자들이 다량으로 느슨하게 붙어있는 다공질구조로 외부에 노출되는 표면적이 넓었으며, 압출성형한천은 굴곡, 요철 및 균열이 생겨서 수분침투가 용이한 구조를 이루고 있었다. Agar has widely been used as medical aids and food ingredients due to its pecular physicochemical and rheological properties. In this paper, the effects of spray drying and extrusion drying on functional properties of agar were investigated to clarify the sol-gel transition mechanism at low temperature and microstructure of agar gel by measuring phase transition by differential scanning calorimetery, structural differences by light microscope and scanning electron microscope observation. The lowest endothermic onset(T_o), peak(T_p), conclusion(T_c) temperature and enthalpy(△H) using differential scanning calorimetery were showed in extrusion-dried agar which were checked in 41.30, 61.72, 80.50 and 0.73cal/g. In cases of unmodified and spray-dried, the values were 81.20, 95.51, 112.14 and 3.22cal/g, and 60.11, 76.45, 89.54 and 1.53cal/g, respectively. When all samples were reheated using differential scanning calorimetery after gelling fully, no significant differences of endothermic T_o, T_p, T_c and △H appeared. The surface structure of unmodified agar powder observed by light microscope and scanning electron microscope appeared a continuous surface without any indication of small pores, gaps or point of discontinuity. In cases of spray-dried agar, the unstavble structures with pores was resulted The microstructures of extrusion-dried agar, however, was solid with large gaps and areas of discontinuity in the surface. From the results above, it was suggested that significant differences in phase transition and surface microstructures were clearly related to the physicochemical changes and rheological properties, solubility and gelling ability of the types of agar gel.

상부벽식-하부골조 구조시스템 해석에 관한 연구

金熙球,鄭在吉 홍익대학교 산업기술연구소 1999 産業技術 Vol.9 No.-

A building should be evaluated closely when signs of deterioration such as peeling of the outer skin(i.e., cement finish or even paint) start to indicate. Moreover, small sign of deterioration ; for example, water leakage on the floor, possibly points to a major structural failure. In order to prevent this costly yet avoidable fiasco, tight maintenance and through examination of the buildings should be carried out periodically, particularly the old ones. This study overlooks the general methods of maintenance and preservation. Also, the study suggests diagnosis method for structural evaluation as well.

Littoral Cell Angioma (LCA) Associated with Liver Cirrhosis

김희구,박인서,이정일,정석,이진우,권계숙,이돈행,김범수,김형길,신용훈,김영수,안인선,이건영 연세대학교의과대학 2005 Yonsei medical journal Vol.46 No.1

A littoral cell angioma (LCA) is a rare benign vascular tumor of the spleen. A 60-year-old man, with multiple nodules in imaging study and liver cirrhosis graded as Child-Pugh classification class A, was transferred for splenomegaly. A thrombocytopenia was found on hematological evaluation. Because there was no evidence of hematological and visceral malignancy, a splenectomy was performed for a definitive diagnosis. The histological and immunohistochemical features of the splenic specimens were consistent with a LCA. After the splenectomy, the thrombocytopenia recovered to the normal platelet count. There has been no previous report of a LCA combined with liver cirrhosis. Herein, the first case of a LCA in Korea, diagnosed and treated by a splenectomy, is reported.

유공 경량 H형강보의 거동에 관한 연구

金熙球,鄭在吉 홍익대학교 산업기술연구소 1998 産業技術 Vol.8 No.-

To out openings in the web of H. Beam can provide for the passage of service ducts and result in material savings. This study is to investigate the ultimate load capacity of light H. Beams with multiple circular openings on the web. The result of this study shows that an adjacent opening at the spacing of 1.5 times the reduos dose noe reduce the strength significantly for various ratios of shear to moment, when the diameter of the opening is less than 70% of the beam depth.

치자 황색색소에 대한 변이원성 시험

김희구 한국식품영양학회 1998 韓國食品營養學會誌 Vol.11 No.1

세균을 이용한 복귀돌연변이 시험계는 Salmonella typhimurium 히스티딘 요구성 변이주를 이용하여 염기대치환(base change)의 돌연변이를 검출하는 S. typhimurium TA100, TA1535와 frameshift형의 돌연변이를 검출하는 S. typhimurium TA98, TA-1537로 구성되어 있으며, 화학물질의 변이원성에 의하여 히스티딘 비요구성으로 복귀하는 돌연변이를 검토하는 시험계로 널리 이용되고 있다^13). 시험결과, Yellow pigment는 S. typhimurium에 대한 독성도 나타나지 않았으며, 배지 1ml당 200㎍ 이하의 모든 농도에서 S-9 Mix(대사활성계)의 유무에 관계없이 S. typhimurium 모든 변이주에서 히스티딘 요구성에 대한 복귀돌연변이를 유발하지 않는 물질로 판단되었다. 이상의 결과로부터 치자황색색소는 S. typhimurium을 이용한 복귀돌연변이시험에서 유전독성이 없는 물질로 사료되었다. Gardenia yellow pigment produced by Gardenia jasminoides Ellis was tested for reverse mutagenic test in Salmonella typhimurium strains TA1535, TA1537, TA98 and TA100 at concentrations raging from 6.25 to 200 ㎍/ml per plate. No significant reverse mutagenic activity was observed in any of the S. typhimurium strains, in either presence or absence of S9 mix. There was no toxicity to the bacteria. These result indicate that yellow pigment doesn't have mutagenicity.

철근 콘크리트 구조와 철골 구조 아파트의 비교 관찰

金熙球 홍익대학교 산업기술연구소 1997 産業技術 Vol.7 No.-

This is a comparative study between r.c and s.s apartment of 15 stories. (1) The cost of construction of s.s apartment is 40-50% expensive comparing with that of r.c apartment. (2) The utility of inside space of s.s apartment is better than that of r.c apartment. (3) The unit height of story of r.e apartment is 2.6 - 2.8m, but that of s.s apartment is 3.3m. (4) The easiness of construction are same for both apartments. (5) We need more studies about economy of two apartment.

경량 조립식 연속난방시스템의 효율성 고찰

金熙球 弘益大學校 1991 弘大論叢 Vol.23 No.2

This is a study on efficiency of light weight sectional continuous heating system. Comparing with usual intermittent heating system(heavy ondol system), light weight sectional continuous heating system has some of efficiency and advantages as follows. 1) We can save 26% of reinforcing steel bar in two way slab, 7%~10% in one way slab of apartment, 3%~7% in footing, and 15% of concrete mass in footing. 2) We can save total cost of construction because of ready-made heating system. 3) It gives better utility of land for us because of lower height of story.

천연식용색소 개발을 위한 치자에서 황색소의 추출

김희구,손홍주 한국식품영양학회 1997 韓國食品營養學會誌 Vol.10 No.2

천dus식용색소를 제조하기 위하여 치자를 이용하여 색소추출의 최적조건과 황색 4호와의 내열성 및 내광성을 조사하였다. 에탄올을 추출용매로 사용한 경우 색소추출 최적조건은 추출온도 40℃, 추출시간 42시간, 추출 pH 7.0 및 기질농도 10%였다. 물추출의 경우 추출온도는 70℃, 추출시간 48시간, 추출 pH 7.0 및 기질농도 10%였다. 최적조건에서의 추출수율은 에탄올의 경우 75%였고, 물추출의 경우는 63%로 나타났다. 황색4호와 치자 황색소의 내열성 및 내광성을 비교 검토한 결과, 황색 4호는 내열설과 내광성이 모두 98%이상으로 나타났으나, 치자 황색소의 경우는 내열성은 62%, 내광성은 90%로 나타났다. In order to make natural food color from Gardenia, we invsetigated optimal conditions of color extraction, and thermal stability and light stability of color extracted compared with Yellow-4. In case of ethanol extraction, optimal conditoins for color extraction were substrate 10%, 40℃, pH7.0 and 42hrs, respectively. In case of water extraction, optimal conditions for color extraction were substrate 10%, 70℃, pH 7.0 and 48hrs, respectively. Extraction yield in the optimal conditons was 75% in ethanol and 63% in water. The thermal stability and light stability of Yellow-4 were both upper 98%, but those of Gardenia yellow color were 62 and 90%, respectively.

한국 초고층 아파트 내력벽식 건물의 내진성 고찰

金熙球 홍익대학교 산업기술연구소 1996 産業技術 Vol.6 No.-

This is a study on seismic design of high rise bearing wall apartment buildings of Korea. The study about earthquake pattern of Korean peninsula is too short to make clear about activity of faulting. So seismic design factor of Korea is a kind of possibilism. If seismic regional factor 0.12 increase to 0.24 of west side of U.S.A(the circus-pan-Pactific earthquake belt)about 23 story bearing wall apartment building, we can have following results. (1) The area of reinforcing bar of bearing wall must be increased as 4.32 for under 9 story to that by Korea seismic code. (2) In case of 9 story to 19 story, the area of bar must be incerased as 4.34 comparing that of Korea seimic code. (3) In case of 20 story to 23 story, the area of bar must be incerased as 1.25 comparing that of Korea seismic code. (4) Total average increasing area of bar is 3.03 times comparing that of Korea seismic code.