Tube Bank에 있어서 流線의 有無에 따른 壓力降下에 관한 硏究

정경락,정재성,김성종,김능배 전북대학교 공업기술연구소 1986 工學硏究 Vol.17 No.-

Pressure drops have been measured in 80℃ water flowing through two banks of 2.54cm steel tubes. The flow was horizontal and perpendicular to the vertical tube. The tube banks had uniform and non-uniform transverse spacing. The uniform bank was an in-line array, five tubes wide and twenty-one tubes long with 9.525mm clearance between adjacent tubes. In the nonuniform case, a tributary was formed by removing the center row of tubes. Measurements were made with and without progressive removal of water through a grid of uniform openings in the bottom tube sheet.

TiO_2 超微粒子의 相轉移에 관한 연구

정경락,변윤섭,김성종,장경환,양영석,정인수 전북대학교 공업기술연구소 1991 工學硏究 Vol.22 No.-

본 연구는 염소법으로 TiCl_4와 O²를 기상반응시켜 TiO²초미립자를 제조하여 생성된 Anatase 형 TiO_2를 대상으로 Anatase-Rutile의 상전이, 첨가제 및 기체 주위조건의 영향을 연구하였다. 연구결과를 요약하면 다음과 같다. 1. Anatase-Rutile의 상전이 반응에서 주된 변수는 온도이며, 속도식은 Avrami식의 결정생성과 성장모델을 따른다고 할 수 있으며, 활성화 에너지는 70kcal/mole이었다. 2. 첨가제 및 기체 주위조건의 영향에 대해서 CuO의첨가는 전이를 촉진시키는 역학을 하였으며, 진공에서는 억제시키는 것으로 나타났다. 3. Anatase형에서 Rutile형으로의 상전이 메카니즘은 Rutile핵 생성 자리가 될 수 있는 외부이온의 확산 또는 기체 주위조건의 영향에 의해 음이온 공백을 형성하고, 음이온 공백은 티타네이트 화학물을 생성한다. 이런 단계를 거치면서 Anatase형 안에서 격자결함을 유발시켜 Rutile형으로의 전이에 영향을 미치는 것이라 할 수 있다.

제 12 회 분체공학 하계 워크샵을 마치고

정경락 한국화학공학회 1998 NICE Vol.16 No.5

유비무환

정경락 한국화학공학회 1995 NICE Vol.13 No.1

섬유상활성탄에 의한 수용액중 페놀류의 흡착특성

정경락,장경환 全北大學校 1992 論文集 Vol.34 No.-

The adsorption characteristics of phenols by the surface-modified activated carbon fibers from its aqueous solution was examined. Cellulose activated carbon fiber(toyobo Co. KF-1500) was used as an adsorbent, and it was treated with heat, air and helium. Pore-size distribution, BET surface area and surfce acidity were measured. The adsorption isotherms were found to conform with the Freundlich equation and its k values were ranged from 1.5381 to 3.6076 mmol/ g and its 1/ n values were ranged from 0.1798 to 0.3144. The affinity of each adsorbate on activated carbon fiber increased in the order ; Phenol <PCP<PNP. The adsorption capacity decreased when oxidized carbon was used, while it increased when redused carbon was used. The adsorption capacity increased when its surface area increased. It is concluded that the adsorption capacity changes in relation with the surface oxides and the surface area of the activated carbon fiber.

제11회 분체공학 기술교육 세미나를 마치고

정경락 한국화학공학회 1999 NICE Vol.17 No.2

TiO_2 超微粒子의 熱的 擧動에 관한 연구

정경락,변윤섭,김성종,장경환,양영석,정인수 전북대학교 공업기술연구소 1991 工學硏究 Vol.22 No.-

Anatase TiO_2 particles prepared by experiment were used to study change of crystal structure by calcination temperature. The results were as follows. Crystallite size of anatase TiO_2 particles increased with calcination temperature. The rate of increasing the crystallite size of anatas TiO_2 particles was decreased below 700℃ and was markedly increased above 700℃. Unit cell volume of TiO_2 was expanded at low temperature and was contracted at high temperature. This result means that the growth of crystallite size was occurred in the C direction.

化學技術情報에 대한 定期刊行物의 素引作業에 關한 硏究

鄭炅樂 全北大學校 1976 論文集 Vol.18 No.-

The uniterm card system and the termatrex card system, both based on the principle of coordinats indexing, have been analyed as specified below, along with the analysis of thesaurus as a term control descriptor. (1) The uniterm card system: merits: a. easy to use even without technical knowledge. b. inexpensive c. possible to store much information with few cards. d. mechanizable by the method of concept coordination. e. convenient as a means of storing and retrieving documents concerning single subjects. demerits: a. its user should have sufficient knowledge about the subject matters concerned to arrange various relations among uniterms and to modify word order and meanings. b. the system is complex and requires time and efforts in analyzing subject matter. c. it is difficult to store much information in smallsized cards. d. the retrieval process in complicated. (2) The termatrex card system: merits: a. the retrieval process is simple. b. information can be retrieved with little expense. c. it is easy to use. d. information retrieval takes little time. e. it is possible to select or add any indexing terms. demerits: a. the amount of information storage is limited to 100,000 items, due to the design of cards. b. The installation of input machines costs much. c. Input processes require much efforts. d. Materials cannot be retrieved directly: only their code numbers are retrieved. e. it is difficult to revise information file. f. the functions of storage and retrieval are not interrelated. (3) These systems are applicable to: a. retrieval of pattern information. b. management of research reports. c. management of (architectrual) desingns. d. management of medical research material. e. personnel management. f. management of properties and lands. g. management of information on chemical products. h. development of ready-made articles. (4) In thesaurus, the meaning, hierarchy, and connotation of terms are well specified and controlled, so the thesaurus can be valuable for the classification, storage, retrieval, and distribution of information. On the other hand, the descrpitor should be used only by those who sufficiently know how to use it, because it is too restricted to accommodate natural language. Since the uniterm card system and termatrex card system are simple, inexpensive, and practical methods of information storage and retrieval, they can be usefully adopted as means of pre-computer analysis of technical and scientific information.

Hopper에 있어서 粉粒體의 流動에 關한 硏究

鄭炅樂 전북대학교 공업기술연구소 1976 工學硏究 Vol.5 No.-

These studies were intented to give basic informations on the Gravitational Flow of Granular Materials from a Hopper. Results are summarized as follows; If we could sum up many studies on the Gravitational Flow of Granular Materials from a Hopper two fields, those have to be the Gravitational Flow Mechanism and the Gravitational Flow Rate. Even if we take a little account of Size Distribution and Cohesive Force of Granular Materials, we are found to obtain the materials for a proper design from previous Empirical Equations, when General Equation required to calculate the Flow Rate Equation of Granular Materials from a Hopper is not discovered.

氣相反應에 依한 酸化物 超微粒子의 製造

鄭炅樂,金成種,張京桓,卞潤燮,梁榮錫,鄭寅洙 전북대학교 공업기술연구소 1990 工學硏究 Vol.21 No.-

The production of TiO_2 ultrafine particles from TiCl_4 and oxygen by the vapor phase reaction was investigated at 850~1000℃, whith an emphasis on the effects of its operation on the particle size distribution of the products. The results were as follows: 1) The average particle size of TiO_2 was 0.191~0.213μm and its particles were single crystals. 2) The average particle size did smaller with the increasing of reaction temperature. 3) The average particle size of TiO_2 did smaller with the increasing in the oxygen concentration and decreasing in the TiCl_4 concentration. 4) The weight fraction of rutile in the TiO_2 particles gradually increased to 900℃ and increased largely at 1000℃. The weight fraction of rutile in TiO_2 particles attached the reaction tube wall increased rapidly because of the effects of heat treatment. 5) The weight fraction of rutile in the TiO_2 particles decreased with the increasing of the oxygen and TiCL_4 concentration.