• Journal of Korean Society of Occupational and Environmental Hygiene
• /
• v.6 no.1
• /
• pp.97-108
• /
• 1996

A new type of passive samplers were designed and produced by authors. After evaluating the quality of activated carbon by measuring recovery rate of organic vapors and steadiness of sampling rate, activated carbon with 30 - 35 mesh produced by Company S in Korea was selected. In each passive sampler, an amount of 400 mg of the activated carbon was filled in 25-mm cassette and covered by fixed screen (or wire screen with 100 mesh). In addition to the fixed screen, a wind screen (or wire screen with 300 mesh) was also attached at outer face. The sampling rate of the new Korean passive samplers was estimated Conclusions obtained in the study are as follows. 1. Sampling rates of the newly developed Korean passive samplers were affected by sampling time. For n-hexane, sampling rates of 15- and 60-minute samples were 70.92 and 37.45 ml/min, respectively. Sampling rate of both 200- and 450-minute samples was 25.96 ml/min. It is concluded that, when passive samplers are used for measuring organic vapors, samples be collected longer than 60 minutes. 2. Sampling rate of the passive samplers was also affected by airborne concentration of organic vapors. Lower sampling rates were determined at level of 1/2 threshold limit values (TLVs) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). It is recommended that sampling rate of the passive samplers be obtained at site by measuring concentrations using both the NIOSH Method and passive samplers simultaneously. 3. When the passive samplers, which collected organic vapors, were exposed to clean air for five hours, there was no significant loss of organic vapors due to reverse diffusion. 4. When samples were stored at room temperature ($21.8{\pm}0.7^{\circ}C$) and refrigerator ($3.8{\pm}0.7^{\circ}C$), there was no significant difference in the accuracy of results. For trichloroethylene and n-hexane, accuracies were within 25 % at both temperatures until seven days. However, poor accuracy exceeding 25 % was indicated in toluene from the first day. It is recommended that samples be stored at freezing temperature below $0^{\circ}C$. 5. Sampling efficiency was significantly affected by direction of the passive samplers. Results of samplers facing wind and down, respectively, were compared. Lower amount of organic vapors were collected when the sampler was oriented down. It is recommended that, when air velocity is low in plants, the passive samplers be oriented to the wind. However, when air velocity is high, the passive samplers be oriented down.

• Journal of Mushroom
• /
• v.10 no.2
• /
• pp.68-73
• /
• 2012

The plastic culture bottle cap types and accumulated concentration of carbon dioxide, media humidity in the process of medium culture and yield were observed in Pleurotus ostreatus 1,100ml bottle in Iksan, Jeollabuk-do, Korea, during 2011. The concentration of carbon dioxide in the process of medium culture was the highest after 6~11days cultivation irrespective of cap sizes and types. The upper-under 19~38mm perforation hole and under 26~47mm perforation hole of caps in the 1,100ml bottle were best condition for cultivation of mushroom and increased fruit body, 11.4~23.8% and 6.5~17.9%, respectively. However, the upper-under 33mm perforation hole of fruit body were decreased 23.8%. Also it was weak, lose vitality and the lower of biologically activity substance because the upper medium humidity was too dry.

• Journal of the Korean Applied Science and Technology
• /
• v.33 no.3
• /
• pp.483-491
• /
• 2016

Even though the antifogging property of nanosilica coated glass surface is highly increased due to the hydrophilic hydroxyl groups on nanosilica surface, the durability of this property on outdoor glass was diminished rapidly after rain washing. In addition the topology of nanosilica coated glass surface plays very important roles to control an light transmittance or antireflection property. To improve these coating durability and characteristics a hydrophilic nanosilica coating on glass was prepared by coating with 1.5 wt% of nanosilica (Ludox) suspension in the presence of hydrolyzed tetraethylorthosilicate (TEOS). The optimum hydrolysis condition of TEOS in acidic or basic aqueous solution was also examined by contact angle measurement. The final transparent hydrophilic coating layer coated with nanosilica-TEOS in acidic condition (pH=4) showed much improved durability of hydrophilic surface as well as higher visible light transmittance than original uncoated glass by 2 % point.

• Development and Reproduction
• /
• v.2 no.2
• /
• pp.141-148
• /
• 1998

The fine structure of spermatozoa of Pungtungia herzi was examined with scanning and transmission electron microscopies. The spermatozoa of p. herzi are approximately 37.4 ${\mu}{\textrm}{m}$ in length and a relatively simple cell with a spherical nucleus, a short midpiece and a tail. The acrosome is not present as in most teleost fishes. The ultrastructure of spermatozoa represents typical characteristics of cyprinid spermatozoa including the lateral insertion of flagellum, the organization of centriolar complex in shallow nuclear fossa, and the occurrence and asymmetrical arrangement of mitochondria. In the nuclear envelope and mitochondrion, however there were some morphological differences for their ultrastructure. The nuclear envelope is severely undulated and the shallow nuclear fossa contains two centrioles which are at the angle of some 130$^{\circ}$ each other. The most significant feature can be observed with the mitochondrion; five or more mitochondria, which are shown in primary spermatocyte, fuse to form a single one in the mature spermatozoon. The mitochondrial aspect is different from that of other cyprinid spermatozoa, where their mitochondria have a conventional aspect and never fuse to form a mitochondrial derivative. In terms of sperm evolution the fused mitochondria are regarded as the apomorphic character in comparison with the separate mitochondria. The single mitochondrion is not reported in cyprinid spermatozoon except the case of Rhodeus.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.31 no.4
• /
• pp.82-91
• /
• 2003

Experiments to investigate the mixing performance of unlike doublet impinging jets are conducted. Reynolds number of simulants used in this study rages from 1.0 to 1.5 Cold flow test is performed to investigate the hydrodynamic effect and spray of the impinging jets are collected locally and calculated by using Rupe's mixing efficiency equation. Momentum exchanges and relative velocity ratio between two jets are taken as the main parameter to represent the effect of enlargement of the orifice diameter. As diameter ratio increases, the corresponding momentum ratio where maximum mixing efficiency occurs and relative velocity at the maximum mixing efficiency ranges 0.6 to 0.7, respectively. Penetration depth can be taken as a prominent parameter to estimate the mixing efficiency.

• Korean Journal of Environmental Agriculture
• /
• v.21 no.4
• /
• pp.286-290
• /
• 2002

This work has been conducted to investigate the behavior of pesticides in ginseng(Panax ginseng C. A. Meyer) cultivation environment, with a fungicide procymidone as a model pesticide. Procymidone adsorption on ginseng cultivating soil was studied and persistency of procymidone in soil was monitored in indoor incubation experiments at 25$^{\circ}C$ and 10$^{\circ}C$. The soil adsorption coefficients($K_{oc}$) of procymidone were in the range of 513$\sim$743 suggesting the mobility of procymidone in soil is relatively low. Procymidone showed higher persistency in soil under indoor incubation condition than outdoor field condition. The half lives estimated from the first order reaction kinetics were 248 days and 330 days at 25$^{\circ}C$ and 10$^{\circ}C$, respectively.

• Korean Journal of Soil Science and Fertilizer
• /
• v.17 no.4
• /
• pp.381-388
• /
• 1984

Addition of heavy textured red earth is being recommended to improve the texture and nutirent retention capacity of sandy soil in Korea. However, farmers are not favorable to this description because of high transportation cost and hard working. To solve this pending problem a field experiment was carried out to investigate the possibility of application of Zeolite as a foreign earth material to improve the physical and chemical characteristics of sandy soil. The experiment results suggested that Zeolite mixed with the basal N fertilizer would be substituted for other foreign earth materials in aspects of rice yield and nitrogen uptake of rice shoot. On the other hand, ammonium adsorption characteristics of soil and amendments were studied.

• Korean Journal of Crystallography
• /
• v.3 no.1
• /
• pp.37-43
• /
• 1992

KTiOP04 is a nonlinear optical crystal which is most widely used for frequency doubling of the radiation of Nd : YAG laser. In the experiment, sin ale crystals of KTiOP04 were grown by TSSG technique using 3K2W04·P2O5 flux. Low temperature gradient furnace suitable for KTP single crystal growth was used. Seed crystal was placed at the surface of the solution for the purpose of better observation of the growing crystals and the possibility of diameter control. Solution included 66.7mol% KTiOP04 for all experiments and its saturation temperature was 1020℃. The conditions of single crystal growth were as follows: cooling rate 0.2℃/h, crystal rotation rate 50rpm, c -axis seed. Using these conditions, single crystals up to 23 ×25×25mm3 have been groan from about 100cc solution. We have also observed a change in the crystal growth habit which resulted in the formation of large (201) faces and small (100) faces. And some crystals have (101) faces.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.32 no.4
• /
• pp.95-100
• /
• 2004

This paper represents the development of a CLS(Control Loading System) for a target a airplane (KT-1) with mechanical linkage reversible flight control system. The system is composed of mechanical frame, controller, sensing part to measure the force from the stick, driving system generating the reaction forces. The DS1103 DSP(Digital Signal Processor) of the dSpace Corp. was used as the controller. The control algorithm of the CLS and the operational environment including monitoring software and evaluation tools are described. The evaluation of the system was conducted according to the requirement specification. The results of the test were analyzed by comparing with the actual data of the target airplane.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.19 no.4
• /
• pp.61-68
• /
• 2015

Reactive sprays of two propellant combinations(GOx/kerosene and $GN_2O$/ethanol) were observed and compared with each other as a basic research of visualizing supercritical combustion. A shadowgraph imaging method was used to visualize the reactive sprays, and shadowgraph images were converted to density gradient magnitude images to analyse the structure of reactive sprays. The gas-liquid interface of GOx/kerosene spray showed rougher boundary and steeper density gradient near the injector face than the $N_2O$/ethanol at similar combustion chamber pressure. Spray core length was calculated from averaged density gradient magnitude images and it was revealed that spray core length of GOx/kerosene was shorter than that of $GN_2O$/ethanol, although momentum flux ratio of GOx/kerosene propellant combination was lower.