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김석현 한국잔디학회 2004 한국잔디학회지 Vol.18 No.1
The efficient refinement of seed is required to reduce the cost and labor input in artificial propagation of wild plant. This study was carried out to develop methods for collecting and refining tiny seeds from wild plants. For obtaining Phragmites communis seeds, the inflorescence was cut into small fragments using a Straw Cutter and subsequently detached pappus hairs from seed coat by Hammer Mill. The primary refined seeds were passed 1.0 mm sieve. The screened seeds were subjected to Seed Blower with wind speed of 0.25 mㆍsec-1 to collected intact and well-ripen seeds. The seeds of Imperata cylindrica were refined as follows. Inflorescences were cut using a Straw Cutter first. The pappus was removed from cut fragments using a Hammer Mill and subsequently subjected to Seed Scarifier at 500rpm for 60 sec. for further separation. The separated seeds were passed 1.0 mm screen and collected after blowing with Seed Blower of wind speed of 0.15 mㆍsec-1. When the amount of seed was too little to refine with Seed Scarifier and Blower, the procedure was slightly modified from the procedure described above. The crude seed mixture obtained from Hammer Mill step was hand-refined roughly and then immersed into cone. (95%) sulfuric acid for 2 min. and collected floating portion after dilution of sulfuric acid solution 100 times with tap water. The collected seeds were dried and passed 0.149 mm sieve. During seed refining process using mechanical or sulfuric acid treatments, a small portion of damaged seed were evolved, however, the amount was not noticeable as compared to the total amount of collected seeds. Because the germination percentages between hand-refined seeds and seeds refined by above methods were not statistically different, the developed procedures for refining tiny seed of wild plants are helpful to reduce the cost and labor input in artificial propagation of two species.
숭례문 장여 제작 기법을 통해 본 여말선초 건축 기술 연구
김석현 한국건축역사학회 2024 건축역사연구 Vol.33 No.1
본 연구는 숭례문 장여에 남아있는 가공흔적을 고찰하여, 고려 말에서 조선 초기에 사용되었던 공정별 도구를 밝히고 여말선초 시기 고급 건축 조영에 사용된 치목 기술에 대해 논하는 것을 목표로 한다. 연구를 통해 14~15세기 숭례문의 장여 제작 시 제재 기법은 쪼개기 제재법과 더불어 켤톱 제재법 함께 사용되고 있는 것을 확인할 수 있었다. 그리고 목재 마감 가공에는 대패 사용을 확인할 수 있는데, 당시 대패의 사용 특성은 조선시대 후기의 현전하고 있는 대패와 크게 다르지 않았던 것도 추정해 볼 수 있었다. 켤톱 제재와 대패 마감 가공은 태조 및 세종연간 장여 부재에서 모두 볼 수 있으며, 고려시대 말에 켤톱과 대패를 사용하는 기법이 이미 보급되어 있던 것을 규명할 수 있었다. 이를 통해 볼 때 조선 개국 이후 경복궁을 비롯한 한양의 주요 관영 건물과 왕족 및 양반의 제택 등 고급 건축 조영에도 켤톱 제재와 대패 마감 가공 기술이 적용되었을 정황도 엿볼 수 있다. This study aims to examine the cutting traces remaining on the bracket tie beams of Sungnyemun gate, identifying thetools employed during the late Goryeo to early Joseon periods by specific processes, and deliberating on the timbershaping techniques utilized in advanced architectural construction during the late Goryeo to early Joseon eras. Throughthe research, it was confirmed that in the production of Sungnyemun Gate's bracket tie beams during the 14th to 15thcenturies, both the timber splitting and ripsawing methods were used in conjunction. Moreover, the wood finishingprocess revealed the use of a plane. It can be inferred that the characteristics of the plane used during that time werenot significantly different from those observed in the later period of the Joseon dynasty. The ripsawing and planefinishing techniques were evident in various parts of the bracket tie beams of Sungnyemun gate across the reigns of kingTaejo and Sejong, indicating that the techniques involving ripsaw and plane were already prevalent in the late Goryeoperiod. Consequently, it can be inferred that the ripsawing and plane finishing techniques might have been applied in theconstruction of prominent government buildings in Hanyang(Seoul), including Gyeongbokgung Palace, and in theresidences of royalty and nobility after the establishment of the Joseon dynasty.
뇌척수액루가 동반된 전두사골 점액농류 조대술 후 발생한 긴장성 기뇌증 1례
김석현,정재훈,문수진,노환중 대한비과학회 2018 Journal of rhinology Vol.25 No.1
After the trauma of frontoethmoidal sinus, post-traumatic mucocele may occur. Surgical removal of the lesions rarely produces cerebrospinal fluid (CSF) leakage and even delayed tension pneumocephalus. We experienced a case of fronto-ethmoid mucocele complicated with peri-operative CSF leakage and post-operative tension pneumocephalus which was improved by conservative treatment. It is imperative to take into account the potential for tension pneumocephalus when a patient suffers from severe headache after sinus surgery.
김석현,장호식,김정헌 한국철도학회 2001 한국철도학회논문집 Vol.4 No.3
Characteristics of the local vibration modes of an aluminium extruded panel are investigated by the finite element analysis and modal testing. Practical methods to increase the damping of the local resonances are proposed. Effects by filling urethan foam in the core cavity and by coating tar on the panel surface are compared by experiments. Modified panel structures to shift the local resonance frequency band are proposed. The results of the study are utilized to predict the severe local resonances in the aluminium extruded panels and prevent their undesirable effect on the sound insulation.
김석현,김태형,김윤호,한영호 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.A
The Chun-cheon Citizen's Bell was cast in memory of hosting the 2010 world leasure conference and a striking ceremony was held at the city hall on December 31, 2005. In this study, vibration and sound of the bell are measured and the property of the magnificent sound of the bell is scientifically investigated. Frequency components making the sound are identified and how the frequency components decrease with time is observed using waterfall plot(3-dimensional frequency spectrum). Beat characteristics of the hum(1st frequency) and the fundamental(2nd frequency)are examined by experiment. Directivity of the sound radiation of the bell is examined by measuring the vibration and sound in several directions. Duration of the vibration and the sound is estimated using damping ratio.