• Horticultural Science & Technology
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• 제35권4호
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• pp.431-438
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• 2017

This study investigated the effect of pre-planting nitrogen (N) fertilization levels added to a soilless root medium on the growth of 'Dotaerang Dia' tomato seedlings. The N levels were varied for a total of 7 treatments: 0, 100, 250, 500, 750, 1,000, or $1,500mg{\cdot}L^{-1}$. The pH of the root media gradually rose in all treatments as the seedlings grew; however, the differences in the pH were not significant among the treatments. The electrical conductivity (EC) of the root media was significantly different among the treatments from sowing to week three, then drastically decreased after week four, which diminished the differences in the EC among the treatments. At week six, plant height, leaf length, leaf width, number of leaves, and fresh and dry weights of the shoot were highest for the treatment with $500mg{\cdot}L^{-1}N$. In contrast, the treatment with $1,500mg{\cdot}L^{-1}N$ had the lowest results for all growth measurements. The fresh weight was 67% heavier in the $500mg{\cdot}L^{-1}N$ treatment compared to the $1,500mg{\cdot}L^{-1}N$ treatment. The total N content in the tissues was lowest in the treatment with $0mg{\cdot}L^{-1}N$ and highest in the treatment with $1,000mg{\cdot}L^{-1}N$. The contents of calcium (Ca), magnesium (Mg), and metal micronutrients in the tissues were highest in the $250mg{\cdot}L^{-1}N$ treatment. A previous study demonstrated that adjusting the fertilization level to promote growth to over 90% of the maximum growth is a good strategy for lowering production costs and preventing damage due to excessive fertilizer absorption by crops. Our results indicated that the optimal pre-planting N fertilization level for tomato plug seedlings should be lower than $500mg{\cdot}L^{-1}$ and the optimum tissue N contents should be around 3.21% to 4.60%.

• Journal of the Korean Society of School Health
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• 제14권1호
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• pp.115-130
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• 2001

Dieting behaviors prevail among most women and are highly increasing among female adolescents who don't have to lose weight. The dieting behaviors of normal or low weight groups are highly related to the negative impact of health risk behaviors. We need a strategy for intervening in the dieting behaviors of relevant groups. With this background, a study was conducted to examine the current situation of dieting behaviors and related factors in middle school girls, and to provide guidelines for the relevant dieting group. This survey was carried out by self-questionnaires passed out to 901 middle school girls from 3 middle schools in Seoul. Data were collected from April 10th, 2000 to April 17th, 2000 and 794 respondents' data were finally selected for analysis. The instruments of this study were Shin's scale for effects of mass-media, Birleson's depression self-rating scale translated by shim, Rosenberg's self-esteem scale, Smilkstein's Family APGAR score translated by Yoon, Kim's school-related adjustment scale. The credibility of instruments was 0.41~0.83 in the pilot study and 0.70~0.86 in the main study. The summary of results was as follows: 1. The general characteristics of respondents were analyzed. In comparison of grade and dieting behaviors, the subjects of the group perceived that their body image was obeser than their real body image and their ideal body image was slenderer than their current body image. A dieter's body image was seriously distorted. 2. The dieting behaviors were analyzed. The Subjects' BMI was within the normal to low range -- they didn't have to lose weight. But actually 47.3% of the respondents were dieters. Their main dieting methods were exercise(71.8%), computer games(64.9%) such as DDR and pump, and intake reduction(64.1%). Most dieters were using desirable methods such as exercise and intake control. But unhealthy methods such as saunax, smoking and harmful drug-use were also used by a few dieters. The main reason for dieting was attractiveness. The chief resources of dieting methods were mass-media(67.8%), friends(64.3%), and parents & relatives(35.1%). Only a few subjects obtained the information from health professionals. While they were trying to lose weight, 42.1% of the subjects experienced side effects such as dizziness(45.0%), apathy(20.5%), appetite loss(18.5%), amenorrhea and the irregularity of the menstrual cycle(16.6%). 3. The relationship between dieting behaviors and factors was analyzed. Dieting behaviors were significantly related to the experience of menarche, the experience of dating with heterosexuals, perceived body image, self-esteem, depression, family's relationship, school instruction-related adjustment, school life-related adjustment, and the effect of mass-media. After that, the multiple logistic regression was used. The analysis revealed that dating, perceived body image, the experience of menarche and the effect of mass media were significant factors. In conclusion, strategies for preventing irrelevant dieting behaviors are urgently required to enhance female adolescents' ability to choose the right information from countless others and to recognize their optimum body image.

• Asian-Australasian Journal of Animal Sciences
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• 제25권1호
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• pp.98-103
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• 2012

This study was conducted to re-evaluate the dietary vitamin C requirement in juvenile eel, Anguilla japonica by using L-ascorbyl-2-monophosphate (AMP) as the vitamin C source. Five semi-purified experimental diets were formulated to contain 0 ($AMP_0$), 30 ($AMP_{24}$), 60 ($AMP_{52}$), 120 ($AMP_{108}$) and 1,200 ($AMP_{1137}$) mg AMP $kg^{-1}$ diet on a dry matter basis. Casein and defatted fish meal were used as the main protein sources in the semi-purified experimental diets. After a 4-week conditioning period, fish initially averaging $15{\pm}0.3$ g (mean${\pm}$SD) were randomly distributed to each aquarium as triplicate groups of 20 fish each. One of five experimental diets was fed on a DM basis to fish in three randomly selected aquaria, at a rate of 3% of total body weight, twice a day. At the end of the feeding trial, weight gain (WG) and specific growth rate (SGR) for fish fed $AMP_{52}$ and $AMP_{108}$ were significantly higher than those recorded for fish fed the control diet (p<0.05). Similarly, feed efficiency (FE) and protein efficiency ratio (PER) for fish fed $AMP_{52}$ were significantly higher than those for fish fed the control diet (p<0.05). Broken-line regression analysis on the basis of WG, SGR, FE and PER showed dietary vitamin C requirements of juvenile eel to be 41.1, 41.2, 43.9 and 43.1 (mg $kg^{-1}$ diet), respectively. These results indicated that the dietary vitamin C requirement could range from 41.1 to 43.9 mg $kg^{-1}$ diet in juvenile eel when L-ascorbyl-2-monophosphate was used as the dietary source of vitamin C.

• The Korean Journal of Physiology and Pharmacology
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• 제19권6호
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• pp.543-547
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• 2015

We investigated the combined moisturizing effect of liposomal serine and a cosmeceutical base selected in this study. Serine is a major amino acid consisting of natural moisturizing factors and keratin, and the hydroxyl group of serine can actively interact with water molecules. Therefore, we hypothesized that serine efficiently delivered to the stratum corneum (SC) of the skin would enhance the moisturizing capability of the skin. We prepared four different cosmeceutical bases (hydrogel, oil-in-water (O/W) essence, O/W cream, and water-in-oil (W/O) cream); their moisturizing abilities were then assessed using a $Corneometer^{(R)}$. The hydrogel was selected as the optimum base for skin moisturization based on the area under the moisture content change-time curves (AUMCC) values used as a parameter for the water hold capacity of the skin. Liposomal serine prepared by a reverse-phase evaporation method was then incorporated in the hydrogel. The liposomal serine-incorporated hydrogel (serine level=1%) showed an approximately 1.62~1.77 times greater moisturizing effect on the skin than those of hydrogel, hydrogel with serine (1%), and hydrogel with blank liposome. However, the AUMCC values were not dependent on the level of serine in liposomal serine-loaded hydrogels. Together, the delivery of serine to the SC of the skin is a promising strategy for moisturizing the skin. This study is expected to be an important step in developing highly effective moisturizing cosmeceutical products.

• Journal of the Korean Wood Science and Technology
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• 제14권2호
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• pp.43-49
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• 1986

In the light of real situation of Korean timber resources, it is no wonder that Korean economy depends on a lot of imported timber, however, we only need to draw attention how have they kept the balance of payment in the field of forest products trade for the last few decades, until the second oil crisis in 1979. Afterwards, the gap between imports and exports of forest products in terms of value has been widened so far, on account of various reasons inside and outside. However, according to national economic policy to drive more active exportation, new policy and strategy to expend world market of forest products urgently expectable in order to shorten the gap between imports and exports of forest products in the future. On the other hand, the current timber importation policy should be reconsidered, not only to support optimum domestic timber price level so as to compensate timber producers' cost but also to make suitable economic environment to induce new investments in the field of private forestry sector.

• Journal of the Korean Society of Costume
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• 제29권
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• pp.5-22
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• 1996

the present thesis aims to contribute to the further development of the men's wear indus-try in Korea which now confronts the need to adjust itself more actively to the conditions of the coming age of internationalization and free trade. To achieve this this thesis suggests the trade should provide for the changing domestic needs on theone hand and refine its wares as high value-added products in compe-tition with those from the advanced countries in fashion industry on the other, The history of the 'suit' the standard men's attire dates back to 1850 when the 'Ditto suit' was introduced composed of coat waist coat vest and trousers to remain virtually unchanged till the end of the nineteenth cen-tury and the modern men's wear originated in Britain. In Korea since the introduction of western clothes from 1876 custom-made suits had been dominant until 1944 while western clothes earned popular currency between 1945 and 1964 and ready-made suits began to spread with their advantages recognized in terms of practicality convenience and functionality The next phase from 1965 to 1985 witnessed the establishment of a number of ready-made brands although custom-made suits stayed in their height of prosperity until 1975. The turn-ing point for the men's wear industry came in 1975 when high-calss ready-made brands be-gan to turn up with the arrival of large companies in the market matching the change in consumers' life style. The men's wear market went through further diversification and specialization dur-ing the years between 1985. and 1990. Around the year 1990 however the expansion of the business suit industry came to slow down ac-companied by an oversupplied market. The fashion of pragmatism in the 1990s called for the growth of the casual wear department and as consumers' life style became more and more individualized conscious dressing in accord ance with T.P.O established itself as an important branch of culture, Such casual boom is likely to aid in promoting Korea's men's wear indus-try to peer with that of advanced countries. Consumers' fashion sense is now ahead of the trade's as well as being shortcycled highly individualized stylized and diversified. To meet consumers' demands under such circum-stances each company is required to develop its unique soft Know How based on accurate information and strategically specialized plan-ning. The trade should convert its hithero producer-oriented strategy to a new consumer oriented one and actively lead the needs and purchasin g pattern of consumers by providing an efficient and reasonable price policy with optimum supply of merchandise and also by presenting 'our' trend suited to our circum-stances.

• Journal of the Institute of Electronics Engineers of Korea TC
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• 제43권3호
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• pp.39-48
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• 2006

In this paper, we analyze the spectral efficiency of multicarrier-code division multiple access (MC-CDMA) scheme. First, we derive a generalized formula for the spectral efficiency according to the number of subcarriers involved in, code division multiplexing and the number of codes used (i.e., loading factor), under a given set of channel coefficients. Also, we derive a generalized formula for spectral efficiency of various reduced-complexity systems that divide the full sets of subcarriers into several groups of subcarriers for code division multiplexing. Then, through these derivations, we establish an inter-relationship between the frequency selectivity and diversity order according to the number of multipaths. From the results, we choose the smallest code length while maximizing the diversity effect, provide an optimum subcarrier allocation strategy, and finally suggest a system structure for capacity-maximizing under the smallest code length. Through numerical analyses under simulated environments, we analyze the properties of spectral efficiency of various systems with reduced complexity and choose a major contributing factors to system design and a better system design methodology. Finally, we compare the spectral efficiency of the MC-CDMA scheme and orthogonal frequency division multiplexing (OFDM) scheme to make a relationship between both schemes.

• The Korean Journal of Ecology
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• 제25권2호
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• pp.93-100
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• 2002

In order to analyze the life cycle of A. artemisiifolia var. elation dormancy and some environmental factors inducing germination of the seeds were examined. The results were as follows : Dormancy of fertile seeds was broken in part within a month after seed collection in case of adequate moisture and alternating temperature was also effective in breaking dormancy. The temperature range, which allow germination was 12℃ ∼ 32℃. Optimum temperature for germination was 24℃. The seed of A. artemisiifolia var. elatior was light-independent. The difference of storage period appeared to have no particular effect on the viability of seeds at any time during the 9-month storage period. In the increasing temperature(IT) regime, A artemisiifolia var. elatior seeds started to germinate at 16℃, showing the higher temperature the greater germination rate, the final germination percentage was 99.34%. On the other hand, in the decresing temperature(DT) regime, seeds began to germinate at 20℃ with the 1.34% germination. An induced dormancy occurred at 12℃ making the 5.34% fecal germination in the DT regime. Low temperature was more effective to break dormancy than higher temperature Seeds of A. artemisiifolia var. elatior seems to be germinated in mid to late autumn or germination delayed until following spring. The above results suggest these variation of germination response in diverse environmental factors seems to be a physiological strategy to maintain their existence and to reproduce in the extreme thermal variation.

• Korean Journal of Fisheries and Aquatic Sciences
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• 제22권5호
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• pp.306-316
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• 1989

We examined the state of Korean pomfret(Pampus echinogaster) in Korean waters and considered the management strategy of the stock based on the theory yield Per recruit. It is not facile to discriminate Korean pomfret distributed in Korean waters from silver pomfret (p. argenteus) due to the similarities in their external morphologies. For this rea- son, Korean pomfret has been treated in silver pomfret in fisheries statistics of Korea. In this study, we asserted Korean pomfret from pomfrets caught commercially by the morphology, from which we recognized that Korean pomfret took $60\~70\%$ in catch(in weight) and that the smaller the body length, the higher the proportion of Korean pomfret. Parameters estimated for Korean pomfret were as follows: natural mortality(M) = 0.6, fishing mortality(F) =0.924(mean value for $1986\~1988$), age at recruit to fishery($t_r$) =0.19 yrs, age at first capture($t_c$) : 0.49 yrs, and the rate of recruit of age-0 fish to fishery(Q) = 0.29. The results obtained from the theory of yield per recruit indicated that the present state of stock was below the optimum level of exploitation and that the control of fishing intensity rarely had an effect on the increasing of yield. Accordingly, we conclude that proper management can be made by increasing the current age of 0.49 yrs at first capture to 1.5 yrs.

• Transactions of the Korean Society of Mechanical Engineers B
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• 제34권8호
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• pp.767-774
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• 2010

In a passive-type PEMFC stack, axial fans operate to supply both oxidant and coolant to cathode side of the stack. It is possible to make a simple system because the passive-type PEMFC stack does not require additional cooling equipment. However, the performance of a cooling system in which water is used as a coolant is better than that of the air-cooling system. To ensure system reliability, it is essential to make cooling system effective by adopting an optimal stack design. In this study, a numerical investigation has been carried out to identify an optimum cooling strategy. Various channel configurations were applied to the test section. The passive-type PEMFC was tested by varying airflow rate distribution at the cathode side and external heat transfer coefficient of the stack. The best cooling performance was achieved when a channel with thick ribs was used, and the overheating at the center of the stack was reduced when a case in which airflow was concentrated at the middle of the stack was used.