큰 정각재의 가열판과 고주파 진공건조간 건조특성의 비교

정희석,강욱,이철현 한국목재공학회 2002 목재공학 Vol.30 No.2

변장 14.0 ㎝와 16.5 ㎝인 소나무 정각재의 가열판진공건조와 고주파진공건조간의 건조속도, 함수율분포와 比에너지를 비교하였다. 고주파진공건조는 가열판진공건조보다 건조속도 및 변장이 건조속도에 미치는 영향이 컸었다. 가열판진공건조 목재의 재장방향, 두께방향과 폭방향의 함수율분포는 볼록 형태를 나타내었고, 고주파진공건조 목재는 오목 형태를 나타내었다. 가열판진공건조 목재의 폭방향과 두께방향간의 수분경사는 유사하였으나 고주파진공건조 목재의 경우는 폭방향의 수분경사가 두께방향보다 완만하였다. 가열판진공건조와 고주파진공건조의 比에너지곡선은 함수율이 감소할수록 증가하는 경향을 나타내었고, 가열판진공건조의 比에너지는고주파진공건조보다 컸었다. Red pine(Pinus densiflora) square timbers with 14.0 ㎝ and 16.5 ㎝ of face size and 2.4 m long were dried in a vacuum-press kiln and in a radio-frequency/vacuum(RF/V) kiln to compare drying rate, moisture content(MC) distribution and specific energy. RF/V drying rate was higher than vacuum-press drying rate. The effect of size of cross section on the RF/V drying rates were more pronounced than those of vacuum-press drying. The longitudinal- and the transverse MC distribution of dried square timber showed convex profile for the vacuum-press drying and concave profile for the RF/V drying. Moisture gradient of width direction was similar to the thickness direction in vacuum-press dried square timber and was more slight than that of the thickness direction in the RF/V dried large square timber. The specific energy consumption curve increased as MC decreased. Specific energy(kWh/㎏ of water evaporated) of the vacuum-press process required more than that of the RF/V process.

침엽수 구조용 정각재의 천연건조곡선과 함수율분포

정희석,이철현,강욱,엄창득 한국목재공학회 2003 목재공학 Vol.31 No.1

이 논문은 소나무와 일본잎갈나무의 변장 14.0cm와 16.5cm인 큰 정각재의 천연건조과정과 함수율분포에 관한 내용으로서 건조속도는 건조개시 첫 8주 동안 비교적 컸었으나 그 이후부터 점차 감소하였다. 생재에서 규격함수율 18% 수준까지 건조시간은 소나무 14.0cm와 16.5cm가 각각 26주와 32주이고, 일본잎갈나무의 경우는 각각 32주와 48주이었다. 이들 정각재의 재장방향과 두께방향의 수분경사는 비교적 완만하였다. 일본잎갈나무의 수분경사는 소나무의 것보다 컸었고, 일본잎갈나무의 변장의 크기가 수분경사에 미치는 영향은 소나무의 것보다 컸었다. This paper presents the results of air-drying processes and mositure content (MC) distribution of red pine (P. densiflora) and Japanese larch (I. leptolepis) square timber with 14 cm and 16.5 cm of face size, respectively. The air-drying rates of square timber were comparatively high during the first 8 weeks, after that gradually decreased. The time to air dry square timber from initial MC to specified MC of 18 percent required about 26 weeks for 14.0 cm and 32 weeks for 16.5 cm square of red pine, and 32 weeks for 14.0 cm and 48 weeks for 16.5 cm square of Japanese larch. The longitudinal-and transverse MC distribution of these air-dried squares showed slight moisture gradient. The effect of face size on moisture gradient of Japanese larch square was more pronounced comparing with red pine one.

솔-젤법에 의한 Nb_2O_5-Fe_2O_3 혼합산화물의 제조 및 산 특성조사

정석조,양희정,권재범,이내우,우희철 釜慶大學校 2000 釜慶大學校 論文集 Vol.5 No.-

In this study, some of results from a study conducted on the preparation of niobium coated hematite particles to be used as a catalyst are presented.α-Fe_2O_3 (hematite) particles obtained by aging an acidic solution of ferric(Ⅲ) ions at high temperature were first prepared as core particles and synthesised by hydrolysis at high temperature with layers of amorphous niobium pentaoxide (Nb_2O_5) deposited by the hydrolysis of niobium pentachloride. The effects of varying molecular ratio of Nb/Fe (10/1, 5/1, 1/2, 1/5, 1/10) were studied. The synthesised particles were characterized for their physical and chemical properties using XRD, SEM, TPD, BET etc. The process of the surface coating showed heterocoagulation rather than surface nucleation and growth. A preliminary investigation of the acidic characterization and specific surface area of the synthesised particles showed that these particles can achieve an acidic characteristic changed and enhanced specific surface area of that of pure niobia and α-Fe_2O_3 prepared here.

1,2-Benzisothiazol-3-one-1,1-Dioxide 유도체의 합성

정대일,정희철,변석인,이용균,박유미,최순규,한정태 東亞大學校附設基礎科學硏究所 2002 基礎科學硏究論文集 Vol.19 No.1

사카린 유도체는 제초제, 항독성, 살균제 등에 광범위하게 연구되어져 오고 있다. 새로운 농략 활성을 가진 물질을 합성하기 위해 먼저 선도물질로 사카린 1을 산화, 염소화 시킨 3-chloro-1,2-benzisothiazol-1,1-dioxide(BID-CI) 2와2cholromethy-1,2-benzisohizol-3-one1,1-dioxide 4를 합성하였다. 선도물질, amines, imidazoles, trones등과 반응시켜 다음과 같은 물질들을 얻었다. ; 3-cyclohexylamino-1,2-benzisothiazol-1,1-dioxide 6, 3-furylamino-1,2-benzisothiazol-1,1-dioxide 8, 3-(3-imidazol)-1,2-benzisothiazol-1,1-dioxide 10, 3-(2-methy-3-imidazol)-1,2-benzisothaizol-1,1-dioxide 12, 2-(3-imidazol)methy-1-1,2-benzisothiazol-3-one-1,1-dioxide 13, and 2-(-3-imidazol)methyl- 1,2-benzisothiazol-1,1-dioxide 14.

정상 관동맥을 가진 심장 점액종 환자에서 발생한 급성 심근 경색증 1예

이정민,이현승,전은정,윤호중,정욱성,오용석,김철민,김재형,최규보,홍순조,이교영,심상인 대한순환기학회 1998 Korean Circulation Journal Vol.28 No.9

Urea를 이용한 Diesel 자동차 배기가스의 de-NOx 촉매 활성에 관한 연구

온중수,이성철,정석진 慶熙大學校 材料科學技術硏究所 2000 材料科學技術硏究論集 Vol.13 No.-

디젤 자동차의 배출규제를 만족시키기 위해 우리나라를 비롯한 세계의 여러 나라에서 활발히 연구되고 있으며, 본 실험에서는 현재 고정원 SCR 공정의 상업용 de-NOx 촉매로 일반적으로 사용되고 있는 V_(2)O_(5)/TiO_(2) 촉매를 가지고 초희박 연소조건인 Diesel 자동차의 질소산화물 제거용 촉매로의 가능성을 타진하기 위해 여러 공정변수에 따른 실험을 실시하였다 NH_(3)보다 안전하고 취급이 용이한 urea를 환원제로 하여 실험을 실시한 결과 1 mole의 urea가 2 mole의 NH_(3)로 분해된다고 판단되는 350℃이상의 분해온도에서 urea가 주입되었을 때 60%이상의 de-NOx activity를 보였다. 결론적으로, urea를 환원제로 하는 복합촉매 system은 Diesel 자동차의 de-NOx 촉매로써 상당한 적용 가능성을 가진다 하겠다.

JNDI를 이용한 Mobile Agent 기반 망관리시스템

김정철,김강석,송왕철 제주대학교 산업기술연구소 1999 尖端技術硏究所論文集 Vol.10 No.2

Recently, network management technology by delegation has been studied as a kind of network management technology to satisfy the user's requirements. Mobile Agent in the technology issues in the distributed network system. Mobile Agent is a software program which is able to move on network with mission for managing a NE(Network Element). Therefore, We have studied the efficient network management technology which is the network management system based upon Mobile Agent Using JNDI(Java Naming Directory Interface). JNDI is API(Application Program Interface) to support interface which make user's application program to be used the naming & directory service. We have designed and implemented the mobile agent network management system using JNDI. This Mobile Agent system is expected to provide a solution for the conventional centralized network system.

다발성 연조직 종괴를 동반한 급성 림프구성 백혈병의 증례 보고

장정용,허경회,이원진,허민석,이삼선,최순철 대한구강악안면방사선학회 2005 Imaging Science in Dentistry Vol.35 No.2

A 15-year-old patient, who had been diagnosed and treated as Burkitt cell type acute lymphoblastic leukemia (ALLL3) already, visited our department. He complained of gingival enlargement and loosening teeth 1 month ago. The clinical examination revealed anterior open bite, gingival enlargement, and nontender swelling particularly in molar regions of both jaws. Deep periodontal pockets and severe mobility was shown on most of the teeth. The panoramic radiographs showed severe bone destruction and extrusion of the molars. The contrast enhanced CT showed multiple enhanced mass and bone marrow obliteration in both jaws. Chemotherapy was done and the swelling was subsided at 1 month later. In conclusion, radiologic findings of leukemia with soft tissue mass, known as chloroma or granulocytic sarcoma, mimic those of lymphoma, so blood test may be needed for the final diagnosis.

Silent Discharge와 TiO₂광촉매 산화반응을 이용한 VOCs 처리

박석출,정창훈,서정민,최금찬 동아대학교 환경문제연구소 1999 硏究報告 Vol.22 No.2

This study has been carried out for evaluation of VOCs treatment let out at the industrial field using a silent discharge process through process approvement and TiO₂ photocatalytic oxidation. And it was presented experimental results on the silent discharge plasma and TiO₂ photocatalytic oxidation processes at atmospheric pressure gas streams containing diluted concentrations of benzene, toluene, and xylene out of VOCs. It has shown that each concentration, background gas, flowrate, and applied power have effected on three materials decomposition and byproduct distribution. Analyses of benzene, toluene, xylene and byproduct concentration was carried out by GC-FID.

워터스, 파노라마 방사선사진과 Scanora 방사선사진의 상악동 점막비후 진단 결과의 비교

윤숙자,강병철,정현대 大韓口腔顎顔面 放射線學會 1995 Imaging Science in Dentistry Vol.25 No.2

The purpose of this study was to compare the diagnostic performance of Waters' and panoramic view ; maxillary sinus posteroanterior and lateral scanography of ?? for mucosal thickening of maxillary sinus as well as to identify the utility of ?? for the detection of maxillary sinus disease. The assessment was done at 66 maxillary sinuses in 45 patients and the results were as follows ; 1. Estimation of presence or absence of mucosal thickening. The sensitivity, specificity, and positive and negative predictive value of maxillary sinus posteroanterior and lateral scanography were 0.865, 0.860, 0.921, and 0.805 respectively and slightly higher than those of Waters' and panoramic views, which were 0.832, 0.835, 0.903, and 0.728 respectively. However, paired t-test showed no significant differences in the diagnostic performance of the two pairs of imaging modalities. 2. Estimation of the types of mucosal thickening. The diagnostic accuracy for type Ⅰ, Ⅱ, Ⅲ was 75.3% on Waters' and panoramic view ; 77.9% on maxillary sinus posteroanterior and lateral scanography. It was higher on the latter, but showed no significant differences from that on the former. 3. Reliability of interpretation. In intraobserver and interobserver agreement, both overall rates of agreement and kappa-value were slightly higher on maxillary sinus posteroanterior and lateral scanography than on Waters' and panoramic views. There was no significant differences between the two pairs of imaging modalities. These results suggested that scanogram is a useful diagnostic radiography as well as Waters' and panoramic views for detection of maxillary sinusitis.